drivers/net/xen-netback/netback.c

   1 /*
   2  * Back-end of the driver for virtual network devices. This portion of the
   3  * driver exports a 'unified' network-device interface that can be accessed
   4  * by any operating system that implements a compatible front end. A
   5  * reference front-end implementation can be found in:
   6  *  drivers/net/xen-netfront.c
   7  *
   8  * Copyright (c) 2002-2005, K A Fraser
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License version 2
  12  * as published by the Free Software Foundation; or, when distributed
  13  * separately from the Linux kernel or incorporated into other
  14  * software packages, subject to the following license:
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a copy
  17  * of this source file (the "Software"), to deal in the Software without
  18  * restriction, including without limitation the rights to use, copy, modify,
  19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  20  * and to permit persons to whom the Software is furnished to do so, subject to
  21  * the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included in
  24  * all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  32  * IN THE SOFTWARE.
  33  */
  34
  35 #include "common.h"
  36
  37 #include <linux/kthread.h>
  38 #include <linux/if_vlan.h>
  39 #include <linux/udp.h>
  40
  41 #include <net/tcp.h>
  42
  43 #include <xen/xen.h>
  44 #include <xen/events.h>
  45 #include <xen/interface/memory.h>
  46
  47 #include <asm/xen/hypercall.h>
  48 #include <asm/xen/page.h>
  49
  50 /*
  51  * This is the maximum slots a skb can have. If a guest sends a skb
  52  * which exceeds this limit it is considered malicious.
  53  */
  54 #define FATAL_SKB_SLOTS_DEFAULT 20
  55 static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
  56 module_param(fatal_skb_slots, uint, 0444);
  57
  58 /*
  59  * To avoid confusion, we define XEN_NETBK_LEGACY_SLOTS_MAX indicating
  60  * the maximum slots a valid packet can use. Now this value is defined
  61  * to be XEN_NETIF_NR_SLOTS_MIN, which is supposed to be supported by
  62  * all backend.
  63  */
  64 #define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN
  65
  66 typedef unsigned int pending_ring_idx_t;
  67 #define INVALID_PENDING_RING_IDX (~0U)
  68
  69 struct pending_tx_info {
  70         struct xen_netif_tx_request req; /* coalesced tx request */
  71         struct xenvif *vif;
  72         pending_ring_idx_t head; /* head != INVALID_PENDING_RING_IDX
  73                                   * if it is head of one or more tx
  74                                   * reqs
  75                                   */
  76 };
  77
  78 struct netbk_rx_meta {
  79         int id;
  80         int size;
  81         int gso_size;
  82 };
  83
  84 #define MAX_PENDING_REQS 256
  85
  86 /* Discriminate from any valid pending_idx value. */
  87 #define INVALID_PENDING_IDX 0xFFFF
  88
  89 #define MAX_BUFFER_OFFSET PAGE_SIZE
  90
  91 /* extra field used in struct page */
  92 union page_ext {
  93         struct {
  94 #if BITS_PER_LONG < 64
  95 #define IDX_WIDTH   8
  96 #define GROUP_WIDTH (BITS_PER_LONG - IDX_WIDTH)
  97                 unsigned int group:GROUP_WIDTH;
  98                 unsigned int idx:IDX_WIDTH;
  99 #else
 100                 unsigned int group, idx;
 101 #endif
 102         } e;
 103         void *mapping;
 104 };
 105
 106 struct xen_netbk {
 107         wait_queue_head_t wq;
 108         struct task_struct *task;
 109
 110         struct sk_buff_head rx_queue;
 111         struct sk_buff_head tx_queue;
 112
 113         struct timer_list net_timer;
 114
 115         struct page *mmap_pages[MAX_PENDING_REQS];
 116
 117         pending_ring_idx_t pending_prod;
 118         pending_ring_idx_t pending_cons;
 119         struct list_head net_schedule_list;
 120
 121         /* Protect the net_schedule_list in netif. */
 122         spinlock_t net_schedule_list_lock;
 123
 124         atomic_t netfront_count;
 125
 126         struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
 127         /* Coalescing tx requests before copying makes number of grant
 128          * copy ops greater or equal to number of slots required. In
 129          * worst case a tx request consumes 2 gnttab_copy.
 130          */
 131         struct gnttab_copy tx_copy_ops[2*MAX_PENDING_REQS];
 132
 133         u16 pending_ring[MAX_PENDING_REQS];
 134
 135         /*
 136          * Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
 137          * head/fragment page uses 2 copy operations because it
 138          * straddles two buffers in the frontend.
 139          */
 140         struct gnttab_copy grant_copy_op[2*XEN_NETIF_RX_RING_SIZE];
 141         struct netbk_rx_meta meta[2*XEN_NETIF_RX_RING_SIZE];
 142 };
 143
 144 static struct xen_netbk *xen_netbk;
 145 static int xen_netbk_group_nr;
 146
 147 /*
 148  * If head != INVALID_PENDING_RING_IDX, it means this tx request is head of
 149  * one or more merged tx requests, otherwise it is the continuation of
 150  * previous tx request.
 151  */
 152 static inline int pending_tx_is_head(struct xen_netbk *netbk, RING_IDX idx)
 153 {
 154         return netbk->pending_tx_info[idx].head != INVALID_PENDING_RING_IDX;
 155 }
 156
 157 void xen_netbk_add_xenvif(struct xenvif *vif)
 158 {
 159         int i;
 160         int min_netfront_count;
 161         int min_group = 0;
 162         struct xen_netbk *netbk;
 163
 164         min_netfront_count = atomic_read(&xen_netbk[0].netfront_count);
 165         for (i = 0; i < xen_netbk_group_nr; i++) {
 166                 int netfront_count = atomic_read(&xen_netbk[i].netfront_count);
 167                 if (netfront_count < min_netfront_count) {
 168                         min_group = i;
 169                         min_netfront_count = netfront_count;
 170                 }
 171         }
 172
 173         netbk = &xen_netbk[min_group];
 174
 175         vif->netbk = netbk;
 176         atomic_inc(&netbk->netfront_count);
 177 }
 178
 179 void xen_netbk_remove_xenvif(struct xenvif *vif)
 180 {
 181         struct xen_netbk *netbk = vif->netbk;
 182         vif->netbk = NULL;
 183         atomic_dec(&netbk->netfront_count);
 184 }
 185
 186 static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
 187                                   u8 status);
 188 static void make_tx_response(struct xenvif *vif,
 189                              struct xen_netif_tx_request *txp,
 190                              s8       st);
 191 static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
 192                                              u16      id,
 193                                              s8       st,
 194                                              u16      offset,
 195                                              u16      size,
 196                                              u16      flags);
 197
 198 static inline unsigned long idx_to_pfn(struct xen_netbk *netbk,
 199                                        u16 idx)
 200 {
 201         return page_to_pfn(netbk->mmap_pages[idx]);
 202 }
 203
 204 static inline unsigned long idx_to_kaddr(struct xen_netbk *netbk,
 205                                          u16 idx)
 206 {
 207         return (unsigned long)pfn_to_kaddr(idx_to_pfn(netbk, idx));
 208 }
 209
 210 /* extra field used in struct page */
 211 static inline void set_page_ext(struct page *pg, struct xen_netbk *netbk,
 212                                 unsigned int idx)
 213 {
 214         unsigned int group = netbk - xen_netbk;
 215         union page_ext ext = { .e = { .group = group + 1, .idx = idx } };
 216
 217         BUILD_BUG_ON(sizeof(ext) > sizeof(ext.mapping));
 218         pg->mapping = ext.mapping;
 219 }
 220
 221 static int get_page_ext(struct page *pg,
 222                         unsigned int *pgroup, unsigned int *pidx)
 223 {
 224         union page_ext ext = { .mapping = pg->mapping };
 225         struct xen_netbk *netbk;
 226         unsigned int group, idx;
 227
 228         group = ext.e.group - 1;
 229
 230         if (group < 0 || group >= xen_netbk_group_nr)
 231                 return 0;
 232
 233         netbk = &xen_netbk[group];
 234
 235         idx = ext.e.idx;
 236
 237         if ((idx < 0) || (idx >= MAX_PENDING_REQS))
 238                 return 0;
 239
 240         if (netbk->mmap_pages[idx] != pg)
 241                 return 0;
 242
 243         *pgroup = group;
 244         *pidx = idx;
 245
 246         return 1;
 247 }
 248
 249 /*
 250  * This is the amount of packet we copy rather than map, so that the
 251  * guest can't fiddle with the contents of the headers while we do
 252  * packet processing on them (netfilter, routing, etc).
 253  */
 254 #define PKT_PROT_LEN    (ETH_HLEN + \
 255                          VLAN_HLEN + \
 256                          sizeof(struct iphdr) + MAX_IPOPTLEN + \
 257                          sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE)
 258
 259 static u16 frag_get_pending_idx(skb_frag_t *frag)
 260 {
 261         return (u16)frag->page_offset;
 262 }
 263
 264 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
 265 {
 266         frag->page_offset = pending_idx;
 267 }
 268
 269 static inline pending_ring_idx_t pending_index(unsigned i)
 270 {
 271         return i & (MAX_PENDING_REQS-1);
 272 }
 273
 274 static inline pending_ring_idx_t nr_pending_reqs(struct xen_netbk *netbk)
 275 {
 276         return MAX_PENDING_REQS -
 277                 netbk->pending_prod + netbk->pending_cons;
 278 }
 279
 280 static void xen_netbk_kick_thread(struct xen_netbk *netbk)
 281 {
 282         wake_up(&netbk->wq);
 283 }
 284
 285 static int max_required_rx_slots(struct xenvif *vif)
 286 {
 287         int max = DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE);
 288
 289         /* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
 290         if (vif->can_sg || vif->gso || vif->gso_prefix)
 291                 max += MAX_SKB_FRAGS + 1; /* extra_info + frags */
 292
 293         return max;
 294 }
 295
 296 int xen_netbk_rx_ring_full(struct xenvif *vif)
 297 {
 298         RING_IDX peek   = vif->rx_req_cons_peek;
 299         RING_IDX needed = max_required_rx_slots(vif);
 300
 301         return ((vif->rx.sring->req_prod - peek) < needed) ||
 302                ((vif->rx.rsp_prod_pvt + XEN_NETIF_RX_RING_SIZE - peek) < needed);
 303 }
 304
 305 int xen_netbk_must_stop_queue(struct xenvif *vif)
 306 {
 307         if (!xen_netbk_rx_ring_full(vif))
 308                 return 0;
 309
 310         vif->rx.sring->req_event = vif->rx_req_cons_peek +
 311                 max_required_rx_slots(vif);
 312         mb(); /* request notification /then/ check the queue */
 313
 314         return xen_netbk_rx_ring_full(vif);
 315 }
 316
 317 /*
 318  * Returns true if we should start a new receive buffer instead of
 319  * adding 'size' bytes to a buffer which currently contains 'offset'
 320  * bytes.
 321  */
 322 static bool start_new_rx_buffer(int offset, unsigned long size, int head)
 323 {
 324         /* simple case: we have completely filled the current buffer. */
 325         if (offset == MAX_BUFFER_OFFSET)
 326                 return true;
 327
 328         /*
 329          * complex case: start a fresh buffer if the current frag
 330          * would overflow the current buffer but only if:
 331          *     (i)   this frag would fit completely in the next buffer
 332          * and (ii)  there is already some data in the current buffer
 333          * and (iii) this is not the head buffer.
 334          *
 335          * Where:
 336          * - (i) stops us splitting a frag into two copies
 337          *   unless the frag is too large for a single buffer.
 338          * - (ii) stops us from leaving a buffer pointlessly empty.
 339          * - (iii) stops us leaving the first buffer
 340          *   empty. Strictly speaking this is already covered
 341          *   by (ii) but is explicitly checked because
 342          *   netfront relies on the first buffer being
 343          *   non-empty and can crash otherwise.
 344          *
 345          * This means we will effectively linearise small
 346          * frags but do not needlessly split large buffers
 347          * into multiple copies tend to give large frags their
 348          * own buffers as before.
 349          */
 350         if ((offset + size > MAX_BUFFER_OFFSET) &&
 351             (size <= MAX_BUFFER_OFFSET) && offset && !head)
 352                 return true;
 353
 354         return false;
 355 }
 356
 357 /*
 358  * Figure out how many ring slots we're going to need to send @skb to
 359  * the guest. This function is essentially a dry run of
 360  * netbk_gop_frag_copy.
 361  */
 362 unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
 363 {
 364         unsigned int count;
 365         int i, copy_off;
 366
 367         count = DIV_ROUND_UP(skb_headlen(skb), PAGE_SIZE);
 368
 369         copy_off = skb_headlen(skb) % PAGE_SIZE;
 370
 371         if (skb_shinfo(skb)->gso_size)
 372                 count++;
 373
 374         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 375                 unsigned long size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
 376                 unsigned long offset = skb_shinfo(skb)->frags[i].page_offset;
 377                 unsigned long bytes;
 378
 379                 offset &= ~PAGE_MASK;
 380
 381                 while (size > 0) {
 382                         BUG_ON(offset >= PAGE_SIZE);
 383                         BUG_ON(copy_off > MAX_BUFFER_OFFSET);
 384
 385                         bytes = PAGE_SIZE - offset;
 386
 387                         if (bytes > size)
 388                                 bytes = size;
 389
 390                         if (start_new_rx_buffer(copy_off, bytes, 0)) {
 391                                 count++;
 392                                 copy_off = 0;
 393                         }
 394
 395                         if (copy_off + bytes > MAX_BUFFER_OFFSET)
 396                                 bytes = MAX_BUFFER_OFFSET - copy_off;
 397
 398                         copy_off += bytes;
 399
 400                         offset += bytes;
 401                         size -= bytes;
 402
 403                         if (offset == PAGE_SIZE)
 404                                 offset = 0;
 405                 }
 406         }
 407         return count;
 408 }
 409
 410 struct netrx_pending_operations {
 411         unsigned copy_prod, copy_cons;
 412         unsigned meta_prod, meta_cons;
 413         struct gnttab_copy *copy;
 414         struct netbk_rx_meta *meta;
 415         int copy_off;
 416         grant_ref_t copy_gref;
 417 };
 418
 419 static struct netbk_rx_meta *get_next_rx_buffer(struct xenvif *vif,
 420                                                 struct netrx_pending_operations *npo)
 421 {
 422         struct netbk_rx_meta *meta;
 423         struct xen_netif_rx_request *req;
 424
 425         req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 426
 427         meta = npo->meta + npo->meta_prod++;
 428         meta->gso_size = 0;
 429         meta->size = 0;
 430         meta->id = req->id;
 431
 432         npo->copy_off = 0;
 433         npo->copy_gref = req->gref;
 434
 435         return meta;
 436 }
 437
 438 /*
 439  * Set up the grant operations for this fragment. If it's a flipping
 440  * interface, we also set up the unmap request from here.
 441  */
 442 static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 443                                 struct netrx_pending_operations *npo,
 444                                 struct page *page, unsigned long size,
 445                                 unsigned long offset, int *head)
 446 {
 447         struct gnttab_copy *copy_gop;
 448         struct netbk_rx_meta *meta;
 449         /*
 450          * These variables are used iff get_page_ext returns true,
 451          * in which case they are guaranteed to be initialized.
 452          */
 453         unsigned int uninitialized_var(group), uninitialized_var(idx);
 454         int foreign = get_page_ext(page, &group, &idx);
 455         unsigned long bytes;
 456
 457         /* Data must not cross a page boundary. */
 458         BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
 459
 460         meta = npo->meta + npo->meta_prod - 1;
 461
 462         /* Skip unused frames from start of page */
 463         page += offset >> PAGE_SHIFT;
 464         offset &= ~PAGE_MASK;
 465
 466         while (size > 0) {
 467                 BUG_ON(offset >= PAGE_SIZE);
 468                 BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
 469
 470                 bytes = PAGE_SIZE - offset;
 471
 472                 if (bytes > size)
 473                         bytes = size;
 474
 475                 if (start_new_rx_buffer(npo->copy_off, bytes, *head)) {
 476                         /*
 477                          * Netfront requires there to be some data in the head
 478                          * buffer.
 479                          */
 480                         BUG_ON(*head);
 481
 482                         meta = get_next_rx_buffer(vif, npo);
 483                 }
 484
 485                 if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
 486                         bytes = MAX_BUFFER_OFFSET - npo->copy_off;
 487
 488                 copy_gop = npo->copy + npo->copy_prod++;
 489                 copy_gop->flags = GNTCOPY_dest_gref;
 490                 if (foreign) {
 491                         struct xen_netbk *netbk = &xen_netbk[group];
 492                         struct pending_tx_info *src_pend;
 493
 494                         src_pend = &netbk->pending_tx_info[idx];
 495
 496                         copy_gop->source.domid = src_pend->vif->domid;
 497                         copy_gop->source.u.ref = src_pend->req.gref;
 498                         copy_gop->flags |= GNTCOPY_source_gref;
 499                 } else {
 500                         void *vaddr = page_address(page);
 501                         copy_gop->source.domid = DOMID_SELF;
 502                         copy_gop->source.u.gmfn = virt_to_mfn(vaddr);
 503                 }
 504                 copy_gop->source.offset = offset;
 505                 copy_gop->dest.domid = vif->domid;
 506
 507                 copy_gop->dest.offset = npo->copy_off;
 508                 copy_gop->dest.u.ref = npo->copy_gref;
 509                 copy_gop->len = bytes;
 510
 511                 npo->copy_off += bytes;
 512                 meta->size += bytes;
 513
 514                 offset += bytes;
 515                 size -= bytes;
 516
 517                 /* Next frame */
 518                 if (offset == PAGE_SIZE && size) {
 519                         BUG_ON(!PageCompound(page));
 520                         page++;
 521                         offset = 0;
 522                 }
 523
 524                 /* Leave a gap for the GSO descriptor. */
 525                 if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
 526                         vif->rx.req_cons++;
 527
 528                 *head = 0; /* There must be something in this buffer now. */
 529
 530         }
 531 }
 532
 533 /*
 534  * Prepare an SKB to be transmitted to the frontend.
 535  *
 536  * This function is responsible for allocating grant operations, meta
 537  * structures, etc.
 538  *
 539  * It returns the number of meta structures consumed. The number of
 540  * ring slots used is always equal to the number of meta slots used
 541  * plus the number of GSO descriptors used. Currently, we use either
 542  * zero GSO descriptors (for non-GSO packets) or one descriptor (for
 543  * frontend-side LRO).
 544  */
 545 static int netbk_gop_skb(struct sk_buff *skb,
 546                          struct netrx_pending_operations *npo)
 547 {
 548         struct xenvif *vif = netdev_priv(skb->dev);
 549         int nr_frags = skb_shinfo(skb)->nr_frags;
 550         int i;
 551         struct xen_netif_rx_request *req;
 552         struct netbk_rx_meta *meta;
 553         unsigned char *data;
 554         int head = 1;
 555         int old_meta_prod;
 556
 557         old_meta_prod = npo->meta_prod;
 558
 559         /* Set up a GSO prefix descriptor, if necessary */
 560         if (skb_shinfo(skb)->gso_size && vif->gso_prefix) {
 561                 req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 562                 meta = npo->meta + npo->meta_prod++;
 563                 meta->gso_size = skb_shinfo(skb)->gso_size;
 564                 meta->size = 0;
 565                 meta->id = req->id;
 566         }
 567
 568         req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 569         meta = npo->meta + npo->meta_prod++;
 570
 571         if (!vif->gso_prefix)
 572                 meta->gso_size = skb_shinfo(skb)->gso_size;
 573         else
 574                 meta->gso_size = 0;
 575
 576         meta->size = 0;
 577         meta->id = req->id;
 578         npo->copy_off = 0;
 579         npo->copy_gref = req->gref;
 580
 581         data = skb->data;
 582         while (data < skb_tail_pointer(skb)) {
 583                 unsigned int offset = offset_in_page(data);
 584                 unsigned int len = PAGE_SIZE - offset;
 585
 586                 if (data + len > skb_tail_pointer(skb))
 587                         len = skb_tail_pointer(skb) - data;
 588
 589                 netbk_gop_frag_copy(vif, skb, npo,
 590                                     virt_to_page(data), len, offset, &head);
 591                 data += len;
 592         }
 593
 594         for (i = 0; i < nr_frags; i++) {
 595                 netbk_gop_frag_copy(vif, skb, npo,
 596                                     skb_frag_page(&skb_shinfo(skb)->frags[i]),
 597                                     skb_frag_size(&skb_shinfo(skb)->frags[i]),
 598                                     skb_shinfo(skb)->frags[i].page_offset,
 599                                     &head);
 600         }
 601
 602         return npo->meta_prod - old_meta_prod;
 603 }
 604
 605 /*
 606  * This is a twin to netbk_gop_skb.  Assume that netbk_gop_skb was
 607  * used to set up the operations on the top of
 608  * netrx_pending_operations, which have since been done.  Check that
 609  * they didn't give any errors and advance over them.
 610  */
 611 static int netbk_check_gop(struct xenvif *vif, int nr_meta_slots,
 612                            struct netrx_pending_operations *npo)
 613 {
 614         struct gnttab_copy     *copy_op;
 615         int status = XEN_NETIF_RSP_OKAY;
 616         int i;
 617
 618         for (i = 0; i < nr_meta_slots; i++) {
 619                 copy_op = npo->copy + npo->copy_cons++;
 620                 if (copy_op->status != GNTST_okay) {
 621                         netdev_dbg(vif->dev,
 622                                    "Bad status %d from copy to DOM%d.\n",
 623                                    copy_op->status, vif->domid);
 624                         status = XEN_NETIF_RSP_ERROR;
 625                 }
 626         }
 627
 628         return status;
 629 }
 630
 631 static void netbk_add_frag_responses(struct xenvif *vif, int status,
 632                                      struct netbk_rx_meta *meta,
 633                                      int nr_meta_slots)
 634 {
 635         int i;
 636         unsigned long offset;
 637
 638         /* No fragments used */
 639         if (nr_meta_slots <= 1)
 640                 return;
 641
 642         nr_meta_slots--;
 643
 644         for (i = 0; i < nr_meta_slots; i++) {
 645                 int flags;
 646                 if (i == nr_meta_slots - 1)
 647                         flags = 0;
 648                 else
 649                         flags = XEN_NETRXF_more_data;
 650
 651                 offset = 0;
 652                 make_rx_response(vif, meta[i].id, status, offset,
 653                                  meta[i].size, flags);
 654         }
 655 }
 656
 657 struct skb_cb_overlay {
 658         int meta_slots_used;
 659 };
 660
 661 static void xen_netbk_rx_action(struct xen_netbk *netbk)
 662 {
 663         struct xenvif *vif = NULL, *tmp;
 664         s8 status;
 665         u16 flags;
 666         struct xen_netif_rx_response *resp;
 667         struct sk_buff_head rxq;
 668         struct sk_buff *skb;
 669         LIST_HEAD(notify);
 670         int ret;
 671         int nr_frags;
 672         int count;
 673         unsigned long offset;
 674         struct skb_cb_overlay *sco;
 675
 676         struct netrx_pending_operations npo = {
 677                 .copy  = netbk->grant_copy_op,
 678                 .meta  = netbk->meta,
 679         };
 680
 681         skb_queue_head_init(&rxq);
 682
 683         count = 0;
 684
 685         while ((skb = skb_dequeue(&netbk->rx_queue)) != NULL) {
 686                 vif = netdev_priv(skb->dev);
 687                 nr_frags = skb_shinfo(skb)->nr_frags;
 688
 689                 sco = (struct skb_cb_overlay *)skb->cb;
 690                 sco->meta_slots_used = netbk_gop_skb(skb, &npo);
 691
 692                 count += nr_frags + 1;
 693
 694                 __skb_queue_tail(&rxq, skb);
 695
 696                 /* Filled the batch queue? */
 697                 /* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
 698                 if (count + MAX_SKB_FRAGS >= XEN_NETIF_RX_RING_SIZE)
 699                         break;
 700         }
 701
 702         BUG_ON(npo.meta_prod > ARRAY_SIZE(netbk->meta));
 703
 704         if (!npo.copy_prod)
 705                 return;
 706
 707         BUG_ON(npo.copy_prod > ARRAY_SIZE(netbk->grant_copy_op));
 708         gnttab_batch_copy(netbk->grant_copy_op, npo.copy_prod);
 709
 710         while ((skb = __skb_dequeue(&rxq)) != NULL) {
 711                 sco = (struct skb_cb_overlay *)skb->cb;
 712
 713                 vif = netdev_priv(skb->dev);
 714
 715                 if (netbk->meta[npo.meta_cons].gso_size && vif->gso_prefix) {
 716                         resp = RING_GET_RESPONSE(&vif->rx,
 717                                                 vif->rx.rsp_prod_pvt++);
 718
 719                         resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
 720
 721                         resp->offset = netbk->meta[npo.meta_cons].gso_size;
 722                         resp->id = netbk->meta[npo.meta_cons].id;
 723                         resp->status = sco->meta_slots_used;
 724
 725                         npo.meta_cons++;
 726                         sco->meta_slots_used--;
 727                 }
 728
 729
 730                 vif->dev->stats.tx_bytes += skb->len;
 731                 vif->dev->stats.tx_packets++;
 732
 733                 status = netbk_check_gop(vif, sco->meta_slots_used, &npo);
 734
 735                 if (sco->meta_slots_used == 1)
 736                         flags = 0;
 737                 else
 738                         flags = XEN_NETRXF_more_data;
 739
 740                 if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
 741                         flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
 742                 else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
 743                         /* remote but checksummed. */
 744                         flags |= XEN_NETRXF_data_validated;
 745
 746                 offset = 0;
 747                 resp = make_rx_response(vif, netbk->meta[npo.meta_cons].id,
 748                                         status, offset,
 749                                         netbk->meta[npo.meta_cons].size,
 750                                         flags);
 751
 752                 if (netbk->meta[npo.meta_cons].gso_size && !vif->gso_prefix) {
 753                         struct xen_netif_extra_info *gso =
 754                                 (struct xen_netif_extra_info *)
 755                                 RING_GET_RESPONSE(&vif->rx,
 756                                                   vif->rx.rsp_prod_pvt++);
 757
 758                         resp->flags |= XEN_NETRXF_extra_info;
 759
 760                         gso->u.gso.size = netbk->meta[npo.meta_cons].gso_size;
 761                         gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
 762                         gso->u.gso.pad = 0;
 763                         gso->u.gso.features = 0;
 764
 765                         gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
 766                         gso->flags = 0;
 767                 }
 768
 769                 netbk_add_frag_responses(vif, status,
 770                                          netbk->meta + npo.meta_cons + 1,
 771                                          sco->meta_slots_used);
 772
 773                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret);
 774
 775                 xenvif_notify_tx_completion(vif);
 776
 777                 if (ret && list_empty(&vif->notify_list))
 778                         list_add_tail(&vif->notify_list, &notify);
 779                 else
 780                         xenvif_put(vif);
 781                 npo.meta_cons += sco->meta_slots_used;
 782                 dev_kfree_skb(skb);
 783         }
 784
 785         list_for_each_entry_safe(vif, tmp, &notify, notify_list) {
 786                 notify_remote_via_irq(vif->irq);
 787                 list_del_init(&vif->notify_list);
 788                 xenvif_put(vif);
 789         }
 790
 791         /* More work to do? */
 792         if (!skb_queue_empty(&netbk->rx_queue) &&
 793                         !timer_pending(&netbk->net_timer))
 794                 xen_netbk_kick_thread(netbk);
 795 }
 796
 797 void xen_netbk_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb)
 798 {
 799         struct xen_netbk *netbk = vif->netbk;
 800
 801         skb_queue_tail(&netbk->rx_queue, skb);
 802
 803         xen_netbk_kick_thread(netbk);
 804 }
 805
 806 static void xen_netbk_alarm(unsigned long data)
 807 {
 808         struct xen_netbk *netbk = (struct xen_netbk *)data;
 809         xen_netbk_kick_thread(netbk);
 810 }
 811
 812 static int __on_net_schedule_list(struct xenvif *vif)
 813 {
 814         return !list_empty(&vif->schedule_list);
 815 }
 816
 817 /* Must be called with net_schedule_list_lock held */
 818 static void remove_from_net_schedule_list(struct xenvif *vif)
 819 {
 820         if (likely(__on_net_schedule_list(vif))) {
 821                 list_del_init(&vif->schedule_list);
 822                 xenvif_put(vif);
 823         }
 824 }
 825
 826 static struct xenvif *poll_net_schedule_list(struct xen_netbk *netbk)
 827 {
 828         struct xenvif *vif = NULL;
 829
 830         spin_lock_irq(&netbk->net_schedule_list_lock);
 831         if (list_empty(&netbk->net_schedule_list))
 832                 goto out;
 833
 834         vif = list_first_entry(&netbk->net_schedule_list,
 835                                struct xenvif, schedule_list);
 836         if (!vif)
 837                 goto out;
 838
 839         xenvif_get(vif);
 840
 841         remove_from_net_schedule_list(vif);
 842 out:
 843         spin_unlock_irq(&netbk->net_schedule_list_lock);
 844         return vif;
 845 }
 846
 847 void xen_netbk_schedule_xenvif(struct xenvif *vif)
 848 {
 849         unsigned long flags;
 850         struct xen_netbk *netbk = vif->netbk;
 851
 852         if (__on_net_schedule_list(vif))
 853                 goto kick;
 854
 855         spin_lock_irqsave(&netbk->net_schedule_list_lock, flags);
 856         if (!__on_net_schedule_list(vif) &&
 857             likely(xenvif_schedulable(vif))) {
 858                 list_add_tail(&vif->schedule_list, &netbk->net_schedule_list);
 859                 xenvif_get(vif);
 860         }
 861         spin_unlock_irqrestore(&netbk->net_schedule_list_lock, flags);
 862
 863 kick:
 864         smp_mb();
 865         if ((nr_pending_reqs(netbk) < (MAX_PENDING_REQS/2)) &&
 866             !list_empty(&netbk->net_schedule_list))
 867                 xen_netbk_kick_thread(netbk);
 868 }
 869
 870 void xen_netbk_deschedule_xenvif(struct xenvif *vif)
 871 {
 872         struct xen_netbk *netbk = vif->netbk;
 873         spin_lock_irq(&netbk->net_schedule_list_lock);
 874         remove_from_net_schedule_list(vif);
 875         spin_unlock_irq(&netbk->net_schedule_list_lock);
 876 }
 877
 878 void xen_netbk_check_rx_xenvif(struct xenvif *vif)
 879 {
 880         int more_to_do;
 881
 882         RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
 883
 884         if (more_to_do)
 885                 xen_netbk_schedule_xenvif(vif);
 886 }
 887
 888 static void tx_add_credit(struct xenvif *vif)
 889 {
 890         unsigned long max_burst, max_credit;
 891
 892         /*
 893          * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
 894          * Otherwise the interface can seize up due to insufficient credit.
 895          */
 896         max_burst = RING_GET_REQUEST(&vif->tx, vif->tx.req_cons)->size;
 897         max_burst = min(max_burst, 131072UL);
 898         max_burst = max(max_burst, vif->credit_bytes);
 899
 900         /* Take care that adding a new chunk of credit doesn't wrap to zero. */
 901         max_credit = vif->remaining_credit + vif->credit_bytes;
 902         if (max_credit < vif->remaining_credit)
 903                 max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
 904
 905         vif->remaining_credit = min(max_credit, max_burst);
 906 }
 907
 908 static void tx_credit_callback(unsigned long data)
 909 {
 910         struct xenvif *vif = (struct xenvif *)data;
 911         tx_add_credit(vif);
 912         xen_netbk_check_rx_xenvif(vif);
 913 }
 914
 915 static void netbk_tx_err(struct xenvif *vif,
 916                          struct xen_netif_tx_request *txp, RING_IDX end)
 917 {
 918         RING_IDX cons = vif->tx.req_cons;
 919
 920         do {
 921                 make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
 922                 if (cons == end)
 923                         break;
 924                 txp = RING_GET_REQUEST(&vif->tx, cons++);
 925         } while (1);
 926         vif->tx.req_cons = cons;
 927         xen_netbk_check_rx_xenvif(vif);
 928         xenvif_put(vif);
 929 }
 930
 931 static void netbk_fatal_tx_err(struct xenvif *vif)
 932 {
 933         netdev_err(vif->dev, "fatal error; disabling device\n");
 934         xenvif_carrier_off(vif);
 935         xenvif_put(vif);
 936 }
 937
 938 static int netbk_count_requests(struct xenvif *vif,
 939                                 struct xen_netif_tx_request *first,
 940                                 struct xen_netif_tx_request *txp,
 941                                 int work_to_do)
 942 {
 943         RING_IDX cons = vif->tx.req_cons;
 944         int slots = 0;
 945         int drop_err = 0;
 946         int more_data;
 947
 948         if (!(first->flags & XEN_NETTXF_more_data))
 949                 return 0;
 950
 951         do {
 952                 struct xen_netif_tx_request dropped_tx = { 0 };
 953
 954                 if (slots >= work_to_do) {
 955                         netdev_err(vif->dev,
 956                                    "Asked for %d slots but exceeds this limit\n",
 957                                    work_to_do);
 958                         netbk_fatal_tx_err(vif);
 959                         return -ENODATA;
 960                 }
 961
 962                 /* This guest is really using too many slots and
 963                  * considered malicious.
 964                  */
 965                 if (unlikely(slots >= fatal_skb_slots)) {
 966                         netdev_err(vif->dev,
 967                                    "Malicious frontend using %d slots, threshold %u\n",
 968                                    slots, fatal_skb_slots);
 969                         netbk_fatal_tx_err(vif);
 970                         return -E2BIG;
 971                 }
 972
 973                 /* Xen network protocol had implicit dependency on
 974                  * MAX_SKB_FRAGS. XEN_NETBK_LEGACY_SLOTS_MAX is set to
 975                  * the historical MAX_SKB_FRAGS value 18 to honor the
 976                  * same behavior as before. Any packet using more than
 977                  * 18 slots but less than fatal_skb_slots slots is
 978                  * dropped
 979                  */
 980                 if (!drop_err && slots >= XEN_NETBK_LEGACY_SLOTS_MAX) {
 981                         if (net_ratelimit())
 982                                 netdev_dbg(vif->dev,
 983                                            "Too many slots (%d) exceeding limit (%d), dropping packet\n",
 984                                            slots, XEN_NETBK_LEGACY_SLOTS_MAX);
 985                         drop_err = -E2BIG;
 986                 }
 987
 988                 if (drop_err)
 989                         txp = &dropped_tx;
 990
 991                 memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots),
 992                        sizeof(*txp));
 993
 994                 /* If the guest submitted a frame >= 64 KiB then
 995                  * first->size overflowed and following slots will
 996                  * appear to be larger than the frame.
 997                  *
 998                  * This cannot be fatal error as there are buggy
 999                  * frontends that do this.
1000                  *
1001                  * Consume all slots and drop the packet.
1002                  */
1003                 if (!drop_err && txp->size > first->size) {
1004                         if (net_ratelimit())
1005                                 netdev_dbg(vif->dev,
1006                                            "Invalid tx request, slot size %u > remaining size %u\n",
1007                                            txp->size, first->size);
1008                         drop_err = -EIO;
1009                 }
1010
1011                 first->size -= txp->size;
1012                 slots++;
1013
1014                 if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
1015                         netdev_err(vif->dev, "Cross page boundary, txp->offset: %x, size: %u\n",
1016                                  txp->offset, txp->size);
1017                         netbk_fatal_tx_err(vif);
1018                         return -EINVAL;
1019                 }
1020
1021                 more_data = txp->flags & XEN_NETTXF_more_data;
1022
1023                 if (!drop_err)
1024                         txp++;
1025
1026         } while (more_data);
1027
1028         if (drop_err) {
1029                 netbk_tx_err(vif, first, cons + slots);
1030                 return drop_err;
1031         }
1032
1033         return slots;
1034 }
1035
1036 static struct page *xen_netbk_alloc_page(struct xen_netbk *netbk,
1037                                          u16 pending_idx)
1038 {
1039         struct page *page;
1040         page = alloc_page(GFP_KERNEL|__GFP_COLD);
1041         if (!page)
1042                 return NULL;
1043         set_page_ext(page, netbk, pending_idx);
1044         netbk->mmap_pages[pending_idx] = page;
1045         return page;
1046 }
1047
1048 static struct gnttab_copy *xen_netbk_get_requests(struct xen_netbk *netbk,
1049                                                   struct xenvif *vif,
1050                                                   struct sk_buff *skb,
1051                                                   struct xen_netif_tx_request *txp,
1052                                                   struct gnttab_copy *gop)
1053 {
1054         struct skb_shared_info *shinfo = skb_shinfo(skb);
1055         skb_frag_t *frags = shinfo->frags;
1056         u16 pending_idx = *((u16 *)skb->data);
1057         u16 head_idx = 0;
1058         int slot, start;
1059         struct page *page;
1060         pending_ring_idx_t index, start_idx = 0;
1061         uint16_t dst_offset;
1062         unsigned int nr_slots;
1063         struct pending_tx_info *first = NULL;
1064
1065         /* At this point shinfo->nr_frags is in fact the number of
1066          * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
1067          */
1068         nr_slots = shinfo->nr_frags;
1069
1070         /* Skip first skb fragment if it is on same page as header fragment. */
1071         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
1072
1073         /* Coalesce tx requests, at this point the packet passed in
1074          * should be <= 64K. Any packets larger than 64K have been
1075          * handled in netbk_count_requests().
1076          */
1077         for (shinfo->nr_frags = slot = start; slot < nr_slots;
1078              shinfo->nr_frags++) {
1079                 struct pending_tx_info *pending_tx_info =
1080                         netbk->pending_tx_info;
1081
1082                 page = alloc_page(GFP_KERNEL|__GFP_COLD);
1083                 if (!page)
1084                         goto err;
1085
1086                 dst_offset = 0;
1087                 first = NULL;
1088                 while (dst_offset < PAGE_SIZE && slot < nr_slots) {
1089                         gop->flags = GNTCOPY_source_gref;
1090
1091                         gop->source.u.ref = txp->gref;
1092                         gop->source.domid = vif->domid;
1093                         gop->source.offset = txp->offset;
1094
1095                         gop->dest.domid = DOMID_SELF;
1096
1097                         gop->dest.offset = dst_offset;
1098                         gop->dest.u.gmfn = virt_to_mfn(page_address(page));
1099
1100                         if (dst_offset + txp->size > PAGE_SIZE) {
1101                                 /* This page can only merge a portion
1102                                  * of tx request. Do not increment any
1103                                  * pointer / counter here. The txp
1104                                  * will be dealt with in future
1105                                  * rounds, eventually hitting the
1106                                  * `else` branch.
1107                                  */
1108                                 gop->len = PAGE_SIZE - dst_offset;
1109                                 txp->offset += gop->len;
1110                                 txp->size -= gop->len;
1111                                 dst_offset += gop->len; /* quit loop */
1112                         } else {
1113                                 /* This tx request can be merged in the page */
1114                                 gop->len = txp->size;
1115                                 dst_offset += gop->len;
1116
1117                                 index = pending_index(netbk->pending_cons++);
1118
1119                                 pending_idx = netbk->pending_ring[index];
1120
1121                                 memcpy(&pending_tx_info[pending_idx].req, txp,
1122                                        sizeof(*txp));
1123                                 xenvif_get(vif);
1124
1125                                 pending_tx_info[pending_idx].vif = vif;
1126
1127                                 /* Poison these fields, corresponding
1128                                  * fields for head tx req will be set
1129                                  * to correct values after the loop.
1130                                  */
1131                                 netbk->mmap_pages[pending_idx] = (void *)(~0UL);
1132                                 pending_tx_info[pending_idx].head =
1133                                         INVALID_PENDING_RING_IDX;
1134
1135                                 if (!first) {
1136                                         first = &pending_tx_info[pending_idx];
1137                                         start_idx = index;
1138                                         head_idx = pending_idx;
1139                                 }
1140
1141                                 txp++;
1142                                 slot++;
1143                         }
1144
1145                         gop++;
1146                 }
1147
1148                 first->req.offset = 0;
1149                 first->req.size = dst_offset;
1150                 first->head = start_idx;
1151                 set_page_ext(page, netbk, head_idx);
1152                 netbk->mmap_pages[head_idx] = page;
1153                 frag_set_pending_idx(&frags[shinfo->nr_frags], head_idx);
1154         }
1155
1156         BUG_ON(shinfo->nr_frags > MAX_SKB_FRAGS);
1157
1158         return gop;
1159 err:
1160         /* Unwind, freeing all pages and sending error responses. */
1161         while (shinfo->nr_frags-- > start) {
1162                 xen_netbk_idx_release(netbk,
1163                                 frag_get_pending_idx(&frags[shinfo->nr_frags]),
1164                                 XEN_NETIF_RSP_ERROR);
1165         }
1166         /* The head too, if necessary. */
1167         if (start)
1168                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1169
1170         return NULL;
1171 }
1172
1173 static int xen_netbk_tx_check_gop(struct xen_netbk *netbk,
1174                                   struct sk_buff *skb,
1175                                   struct gnttab_copy **gopp)
1176 {
1177         struct gnttab_copy *gop = *gopp;
1178         u16 pending_idx = *((u16 *)skb->data);
1179         struct skb_shared_info *shinfo = skb_shinfo(skb);
1180         struct pending_tx_info *tx_info;
1181         int nr_frags = shinfo->nr_frags;
1182         int i, err, start;
1183         u16 peek; /* peek into next tx request */
1184
1185         /* Check status of header. */
1186         err = gop->status;
1187         if (unlikely(err))
1188                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1189
1190         /* Skip first skb fragment if it is on same page as header fragment. */
1191         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
1192
1193         for (i = start; i < nr_frags; i++) {
1194                 int j, newerr;
1195                 pending_ring_idx_t head;
1196
1197                 pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
1198                 tx_info = &netbk->pending_tx_info[pending_idx];
1199                 head = tx_info->head;
1200
1201                 /* Check error status: if okay then remember grant handle. */
1202                 do {
1203                         newerr = (++gop)->status;
1204                         if (newerr)
1205                                 break;
1206                         peek = netbk->pending_ring[pending_index(++head)];
1207                 } while (!pending_tx_is_head(netbk, peek));
1208
1209                 if (likely(!newerr)) {
1210                         /* Had a previous error? Invalidate this fragment. */
1211                         if (unlikely(err))
1212                                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1213                         continue;
1214                 }
1215
1216                 /* Error on this fragment: respond to client with an error. */
1217                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1218
1219                 /* Not the first error? Preceding frags already invalidated. */
1220                 if (err)
1221                         continue;
1222
1223                 /* First error: invalidate header and preceding fragments. */
1224                 pending_idx = *((u16 *)skb->data);
1225                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1226                 for (j = start; j < i; j++) {
1227                         pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
1228                         xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1229                 }
1230
1231                 /* Remember the error: invalidate all subsequent fragments. */
1232                 err = newerr;
1233         }
1234
1235         *gopp = gop + 1;
1236         return err;
1237 }
1238
1239 static void xen_netbk_fill_frags(struct xen_netbk *netbk, struct sk_buff *skb)
1240 {
1241         struct skb_shared_info *shinfo = skb_shinfo(skb);
1242         int nr_frags = shinfo->nr_frags;
1243         int i;
1244
1245         for (i = 0; i < nr_frags; i++) {
1246                 skb_frag_t *frag = shinfo->frags + i;
1247                 struct xen_netif_tx_request *txp;
1248                 struct page *page;
1249                 u16 pending_idx;
1250
1251                 pending_idx = frag_get_pending_idx(frag);
1252
1253                 txp = &netbk->pending_tx_info[pending_idx].req;
1254                 page = virt_to_page(idx_to_kaddr(netbk, pending_idx));
1255                 __skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
1256                 skb->len += txp->size;
1257                 skb->data_len += txp->size;
1258                 skb->truesize += txp->size;
1259
1260                 /* Take an extra reference to offset xen_netbk_idx_release */
1261                 get_page(netbk->mmap_pages[pending_idx]);
1262                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1263         }
1264 }
1265
1266 static int xen_netbk_get_extras(struct xenvif *vif,
1267                                 struct xen_netif_extra_info *extras,
1268                                 int work_to_do)
1269 {
1270         struct xen_netif_extra_info extra;
1271         RING_IDX cons = vif->tx.req_cons;
1272
1273         do {
1274                 if (unlikely(work_to_do-- <= 0)) {
1275                         netdev_err(vif->dev, "Missing extra info\n");
1276                         netbk_fatal_tx_err(vif);
1277                         return -EBADR;
1278                 }
1279
1280                 memcpy(&extra, RING_GET_REQUEST(&vif->tx, cons),
1281                        sizeof(extra));
1282                 if (unlikely(!extra.type ||
1283                              extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
1284                         vif->tx.req_cons = ++cons;
1285                         netdev_err(vif->dev,
1286                                    "Invalid extra type: %d\n", extra.type);
1287                         netbk_fatal_tx_err(vif);
1288                         return -EINVAL;
1289                 }
1290
1291                 memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
1292                 vif->tx.req_cons = ++cons;
1293         } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
1294
1295         return work_to_do;
1296 }
1297
1298 static int netbk_set_skb_gso(struct xenvif *vif,
1299                              struct sk_buff *skb,
1300                              struct xen_netif_extra_info *gso)
1301 {
1302         if (!gso->u.gso.size) {
1303                 netdev_err(vif->dev, "GSO size must not be zero.\n");
1304                 netbk_fatal_tx_err(vif);
1305                 return -EINVAL;
1306         }
1307
1308         /* Currently only TCPv4 S.O. is supported. */
1309         if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
1310                 netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
1311                 netbk_fatal_tx_err(vif);
1312                 return -EINVAL;
1313         }
1314
1315         skb_shinfo(skb)->gso_size = gso->u.gso.size;
1316         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1317
1318         /* Header must be checked, and gso_segs computed. */
1319         skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
1320         skb_shinfo(skb)->gso_segs = 0;
1321
1322         return 0;
1323 }
1324
1325 static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
1326 {
1327         struct iphdr *iph;
1328         int err = -EPROTO;
1329         int recalculate_partial_csum = 0;
1330
1331         /*
1332          * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
1333          * peers can fail to set NETRXF_csum_blank when sending a GSO
1334          * frame. In this case force the SKB to CHECKSUM_PARTIAL and
1335          * recalculate the partial checksum.
1336          */
1337         if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
1338                 vif->rx_gso_checksum_fixup++;
1339                 skb->ip_summed = CHECKSUM_PARTIAL;
1340                 recalculate_partial_csum = 1;
1341         }
1342
1343         /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
1344         if (skb->ip_summed != CHECKSUM_PARTIAL)
1345                 return 0;
1346
1347         if (skb->protocol != htons(ETH_P_IP))
1348                 goto out;
1349
1350         iph = (void *)skb->data;
1351         switch (iph->protocol) {
1352         case IPPROTO_TCP:
1353                 if (!skb_partial_csum_set(skb, 4 * iph->ihl,
1354                                           offsetof(struct tcphdr, check)))
1355                         goto out;
1356
1357                 if (recalculate_partial_csum) {
1358                         struct tcphdr *tcph = tcp_hdr(skb);
1359                         tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
1360                                                          skb->len - iph->ihl*4,
1361                                                          IPPROTO_TCP, 0);
1362                 }
1363                 break;
1364         case IPPROTO_UDP:
1365                 if (!skb_partial_csum_set(skb, 4 * iph->ihl,
1366                                           offsetof(struct udphdr, check)))
1367                         goto out;
1368
1369                 if (recalculate_partial_csum) {
1370                         struct udphdr *udph = udp_hdr(skb);
1371                         udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
1372                                                          skb->len - iph->ihl*4,
1373                                                          IPPROTO_UDP, 0);
1374                 }
1375                 break;
1376         default:
1377                 if (net_ratelimit())
1378                         netdev_err(vif->dev,
1379                                    "Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
1380                                    iph->protocol);
1381                 goto out;
1382         }
1383
1384         err = 0;
1385
1386 out:
1387         return err;
1388 }
1389
1390 static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
1391 {
1392         unsigned long now = jiffies;
1393         unsigned long next_credit =
1394                 vif->credit_timeout.expires +
1395                 msecs_to_jiffies(vif->credit_usec / 1000);
1396
1397         /* Timer could already be pending in rare cases. */
1398         if (timer_pending(&vif->credit_timeout))
1399                 return true;
1400
1401         /* Passed the point where we can replenish credit? */
1402         if (time_after_eq(now, next_credit)) {
1403                 vif->credit_timeout.expires = now;
1404                 tx_add_credit(vif);
1405         }
1406
1407         /* Still too big to send right now? Set a callback. */
1408         if (size > vif->remaining_credit) {
1409                 vif->credit_timeout.data     =
1410                         (unsigned long)vif;
1411                 vif->credit_timeout.function =
1412                         tx_credit_callback;
1413                 mod_timer(&vif->credit_timeout,
1414                           next_credit);
1415
1416                 return true;
1417         }
1418
1419         return false;
1420 }
1421
1422 static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
1423 {
1424         struct gnttab_copy *gop = netbk->tx_copy_ops, *request_gop;
1425         struct sk_buff *skb;
1426         int ret;
1427
1428         while ((nr_pending_reqs(netbk) + XEN_NETBK_LEGACY_SLOTS_MAX
1429                 < MAX_PENDING_REQS) &&
1430                 !list_empty(&netbk->net_schedule_list)) {
1431                 struct xenvif *vif;
1432                 struct xen_netif_tx_request txreq;
1433                 struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
1434                 struct page *page;
1435                 struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
1436                 u16 pending_idx;
1437                 RING_IDX idx;
1438                 int work_to_do;
1439                 unsigned int data_len;
1440                 pending_ring_idx_t index;
1441
1442                 /* Get a netif from the list with work to do. */
1443                 vif = poll_net_schedule_list(netbk);
1444                 /* This can sometimes happen because the test of
1445                  * list_empty(net_schedule_list) at the top of the
1446                  * loop is unlocked.  Just go back and have another
1447                  * look.
1448                  */
1449                 if (!vif)
1450                         continue;
1451
1452                 if (vif->tx.sring->req_prod - vif->tx.req_cons >
1453                     XEN_NETIF_TX_RING_SIZE) {
1454                         netdev_err(vif->dev,
1455                                    "Impossible number of requests. "
1456                                    "req_prod %d, req_cons %d, size %ld\n",
1457                                    vif->tx.sring->req_prod, vif->tx.req_cons,
1458                                    XEN_NETIF_TX_RING_SIZE);
1459                         netbk_fatal_tx_err(vif);
1460                         continue;
1461                 }
1462
1463                 RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do);
1464                 if (!work_to_do) {
1465                         xenvif_put(vif);
1466                         continue;
1467                 }
1468
1469                 idx = vif->tx.req_cons;
1470                 rmb(); /* Ensure that we see the request before we copy it. */
1471                 memcpy(&txreq, RING_GET_REQUEST(&vif->tx, idx), sizeof(txreq));
1472
1473                 /* Credit-based scheduling. */
1474                 if (txreq.size > vif->remaining_credit &&
1475                     tx_credit_exceeded(vif, txreq.size)) {
1476                         xenvif_put(vif);
1477                         continue;
1478                 }
1479
1480                 vif->remaining_credit -= txreq.size;
1481
1482                 work_to_do--;
1483                 vif->tx.req_cons = ++idx;
1484
1485                 memset(extras, 0, sizeof(extras));
1486                 if (txreq.flags & XEN_NETTXF_extra_info) {
1487                         work_to_do = xen_netbk_get_extras(vif, extras,
1488                                                           work_to_do);
1489                         idx = vif->tx.req_cons;
1490                         if (unlikely(work_to_do < 0))
1491                                 continue;
1492                 }
1493
1494                 ret = netbk_count_requests(vif, &txreq, txfrags, work_to_do);
1495                 if (unlikely(ret < 0))
1496                         continue;
1497
1498                 idx += ret;
1499
1500                 if (unlikely(txreq.size < ETH_HLEN)) {
1501                         netdev_dbg(vif->dev,
1502                                    "Bad packet size: %d\n", txreq.size);
1503                         netbk_tx_err(vif, &txreq, idx);
1504                         continue;
1505                 }
1506
1507                 /* No crossing a page as the payload mustn't fragment. */
1508                 if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
1509                         netdev_err(vif->dev,
1510                                    "txreq.offset: %x, size: %u, end: %lu\n",
1511                                    txreq.offset, txreq.size,
1512                                    (txreq.offset&~PAGE_MASK) + txreq.size);
1513                         netbk_fatal_tx_err(vif);
1514                         continue;
1515                 }
1516
1517                 index = pending_index(netbk->pending_cons);
1518                 pending_idx = netbk->pending_ring[index];
1519
1520                 data_len = (txreq.size > PKT_PROT_LEN &&
1521                             ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
1522                         PKT_PROT_LEN : txreq.size;
1523
1524                 skb = alloc_skb(data_len + NET_SKB_PAD + NET_IP_ALIGN,
1525                                 GFP_ATOMIC | __GFP_NOWARN);
1526                 if (unlikely(skb == NULL)) {
1527                         netdev_dbg(vif->dev,
1528                                    "Can't allocate a skb in start_xmit.\n");
1529                         netbk_tx_err(vif, &txreq, idx);
1530                         break;
1531                 }
1532
1533                 /* Packets passed to netif_rx() must have some headroom. */
1534                 skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
1535
1536                 if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
1537                         struct xen_netif_extra_info *gso;
1538                         gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
1539
1540                         if (netbk_set_skb_gso(vif, skb, gso)) {
1541                                 /* Failure in netbk_set_skb_gso is fatal. */
1542                                 kfree_skb(skb);
1543                                 continue;
1544                         }
1545                 }
1546
1547                 /* XXX could copy straight to head */
1548                 page = xen_netbk_alloc_page(netbk, pending_idx);
1549                 if (!page) {
1550                         kfree_skb(skb);
1551                         netbk_tx_err(vif, &txreq, idx);
1552                         continue;
1553                 }
1554
1555                 gop->source.u.ref = txreq.gref;
1556                 gop->source.domid = vif->domid;
1557                 gop->source.offset = txreq.offset;
1558
1559                 gop->dest.u.gmfn = virt_to_mfn(page_address(page));
1560                 gop->dest.domid = DOMID_SELF;
1561                 gop->dest.offset = txreq.offset;
1562
1563                 gop->len = txreq.size;
1564                 gop->flags = GNTCOPY_source_gref;
1565
1566                 gop++;
1567
1568                 memcpy(&netbk->pending_tx_info[pending_idx].req,
1569                        &txreq, sizeof(txreq));
1570                 netbk->pending_tx_info[pending_idx].vif = vif;
1571                 netbk->pending_tx_info[pending_idx].head = index;
1572                 *((u16 *)skb->data) = pending_idx;
1573
1574                 __skb_put(skb, data_len);
1575
1576                 skb_shinfo(skb)->nr_frags = ret;
1577                 if (data_len < txreq.size) {
1578                         skb_shinfo(skb)->nr_frags++;
1579                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1580                                              pending_idx);
1581                 } else {
1582                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1583                                              INVALID_PENDING_IDX);
1584                 }
1585
1586                 netbk->pending_cons++;
1587
1588                 request_gop = xen_netbk_get_requests(netbk, vif,
1589                                                      skb, txfrags, gop);
1590                 if (request_gop == NULL) {
1591                         kfree_skb(skb);
1592                         netbk_tx_err(vif, &txreq, idx);
1593                         continue;
1594                 }
1595                 gop = request_gop;
1596
1597                 __skb_queue_tail(&netbk->tx_queue, skb);
1598
1599                 vif->tx.req_cons = idx;
1600                 xen_netbk_check_rx_xenvif(vif);
1601
1602                 if ((gop-netbk->tx_copy_ops) >= ARRAY_SIZE(netbk->tx_copy_ops))
1603                         break;
1604         }
1605
1606         return gop - netbk->tx_copy_ops;
1607 }
1608
1609 static void xen_netbk_tx_submit(struct xen_netbk *netbk)
1610 {
1611         struct gnttab_copy *gop = netbk->tx_copy_ops;
1612         struct sk_buff *skb;
1613
1614         while ((skb = __skb_dequeue(&netbk->tx_queue)) != NULL) {
1615                 struct xen_netif_tx_request *txp;
1616                 struct xenvif *vif;
1617                 u16 pending_idx;
1618                 unsigned data_len;
1619
1620                 pending_idx = *((u16 *)skb->data);
1621                 vif = netbk->pending_tx_info[pending_idx].vif;
1622                 txp = &netbk->pending_tx_info[pending_idx].req;
1623
1624                 /* Check the remap error code. */
1625                 if (unlikely(xen_netbk_tx_check_gop(netbk, skb, &gop))) {
1626                         netdev_dbg(vif->dev, "netback grant failed.\n");
1627                         skb_shinfo(skb)->nr_frags = 0;
1628                         kfree_skb(skb);
1629                         continue;
1630                 }
1631
1632                 data_len = skb->len;
1633                 memcpy(skb->data,
1634                        (void *)(idx_to_kaddr(netbk, pending_idx)|txp->offset),
1635                        data_len);
1636                 if (data_len < txp->size) {
1637                         /* Append the packet payload as a fragment. */
1638                         txp->offset += data_len;
1639                         txp->size -= data_len;
1640                 } else {
1641                         /* Schedule a response immediately. */
1642                         xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1643                 }
1644
1645                 if (txp->flags & XEN_NETTXF_csum_blank)
1646                         skb->ip_summed = CHECKSUM_PARTIAL;
1647                 else if (txp->flags & XEN_NETTXF_data_validated)
1648                         skb->ip_summed = CHECKSUM_UNNECESSARY;
1649
1650                 xen_netbk_fill_frags(netbk, skb);
1651
1652                 /*
1653                  * If the initial fragment was < PKT_PROT_LEN then
1654                  * pull through some bytes from the other fragments to
1655                  * increase the linear region to PKT_PROT_LEN bytes.
1656                  */
1657                 if (skb_headlen(skb) < PKT_PROT_LEN && skb_is_nonlinear(skb)) {
1658                         int target = min_t(int, skb->len, PKT_PROT_LEN);
1659                         __pskb_pull_tail(skb, target - skb_headlen(skb));
1660                 }
1661
1662                 skb->dev      = vif->dev;
1663                 skb->protocol = eth_type_trans(skb, skb->dev);
1664                 skb_reset_network_header(skb);
1665
1666                 if (checksum_setup(vif, skb)) {
1667                         netdev_dbg(vif->dev,
1668                                    "Can't setup checksum in net_tx_action\n");
1669                         kfree_skb(skb);
1670                         continue;
1671                 }
1672
1673                 skb_probe_transport_header(skb, 0);
1674
1675                 vif->dev->stats.rx_bytes += skb->len;
1676                 vif->dev->stats.rx_packets++;
1677
1678                 xenvif_receive_skb(vif, skb);
1679         }
1680 }
1681
1682 /* Called after netfront has transmitted */
1683 static void xen_netbk_tx_action(struct xen_netbk *netbk)
1684 {
1685         unsigned nr_gops;
1686
1687         nr_gops = xen_netbk_tx_build_gops(netbk);
1688
1689         if (nr_gops == 0)
1690                 return;
1691
1692         gnttab_batch_copy(netbk->tx_copy_ops, nr_gops);
1693
1694         xen_netbk_tx_submit(netbk);
1695 }
1696
1697 static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
1698                                   u8 status)
1699 {
1700         struct xenvif *vif;
1701         struct pending_tx_info *pending_tx_info;
1702         pending_ring_idx_t head;
1703         u16 peek; /* peek into next tx request */
1704
1705         BUG_ON(netbk->mmap_pages[pending_idx] == (void *)(~0UL));
1706
1707         /* Already complete? */
1708         if (netbk->mmap_pages[pending_idx] == NULL)
1709                 return;
1710
1711         pending_tx_info = &netbk->pending_tx_info[pending_idx];
1712
1713         vif = pending_tx_info->vif;
1714         head = pending_tx_info->head;
1715
1716         BUG_ON(!pending_tx_is_head(netbk, head));
1717         BUG_ON(netbk->pending_ring[pending_index(head)] != pending_idx);
1718
1719         do {
1720                 pending_ring_idx_t index;
1721                 pending_ring_idx_t idx = pending_index(head);
1722                 u16 info_idx = netbk->pending_ring[idx];
1723
1724                 pending_tx_info = &netbk->pending_tx_info[info_idx];
1725                 make_tx_response(vif, &pending_tx_info->req, status);
1726
1727                 /* Setting any number other than
1728                  * INVALID_PENDING_RING_IDX indicates this slot is
1729                  * starting a new packet / ending a previous packet.
1730                  */
1731                 pending_tx_info->head = 0;
1732
1733                 index = pending_index(netbk->pending_prod++);
1734                 netbk->pending_ring[index] = netbk->pending_ring[info_idx];
1735
1736                 xenvif_put(vif);
1737
1738                 peek = netbk->pending_ring[pending_index(++head)];
1739
1740         } while (!pending_tx_is_head(netbk, peek));
1741
1742         netbk->mmap_pages[pending_idx]->mapping = 0;
1743         put_page(netbk->mmap_pages[pending_idx]);
1744         netbk->mmap_pages[pending_idx] = NULL;
1745 }
1746
1747
1748 static void make_tx_response(struct xenvif *vif,
1749                              struct xen_netif_tx_request *txp,
1750                              s8       st)
1751 {
1752         RING_IDX i = vif->tx.rsp_prod_pvt;
1753         struct xen_netif_tx_response *resp;
1754         int notify;
1755
1756         resp = RING_GET_RESPONSE(&vif->tx, i);
1757         resp->id     = txp->id;
1758         resp->status = st;
1759
1760         if (txp->flags & XEN_NETTXF_extra_info)
1761                 RING_GET_RESPONSE(&vif->tx, ++i)->status = XEN_NETIF_RSP_NULL;
1762
1763         vif->tx.rsp_prod_pvt = ++i;
1764         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->tx, notify);
1765         if (notify)
1766                 notify_remote_via_irq(vif->irq);
1767 }
1768
1769 static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
1770                                              u16      id,
1771                                              s8       st,
1772                                              u16      offset,
1773                                              u16      size,
1774                                              u16      flags)
1775 {
1776         RING_IDX i = vif->rx.rsp_prod_pvt;
1777         struct xen_netif_rx_response *resp;
1778
1779         resp = RING_GET_RESPONSE(&vif->rx, i);
1780         resp->offset     = offset;
1781         resp->flags      = flags;
1782         resp->id         = id;
1783         resp->status     = (s16)size;
1784         if (st < 0)
1785                 resp->status = (s16)st;
1786
1787         vif->rx.rsp_prod_pvt = ++i;
1788
1789         return resp;
1790 }
1791
1792 static inline int rx_work_todo(struct xen_netbk *netbk)
1793 {
1794         return !skb_queue_empty(&netbk->rx_queue);
1795 }
1796
1797 static inline int tx_work_todo(struct xen_netbk *netbk)
1798 {
1799
1800         if ((nr_pending_reqs(netbk) + XEN_NETBK_LEGACY_SLOTS_MAX
1801              < MAX_PENDING_REQS) &&
1802              !list_empty(&netbk->net_schedule_list))
1803                 return 1;
1804
1805         return 0;
1806 }
1807
1808 static int xen_netbk_kthread(void *data)
1809 {
1810         struct xen_netbk *netbk = data;
1811         while (!kthread_should_stop()) {
1812                 wait_event_interruptible(netbk->wq,
1813                                 rx_work_todo(netbk) ||
1814                                 tx_work_todo(netbk) ||
1815                                 kthread_should_stop());
1816                 cond_resched();
1817
1818                 if (kthread_should_stop())
1819                         break;
1820
1821                 if (rx_work_todo(netbk))
1822                         xen_netbk_rx_action(netbk);
1823
1824                 if (tx_work_todo(netbk))
1825                         xen_netbk_tx_action(netbk);
1826         }
1827
1828         return 0;
1829 }
1830
1831 void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
1832 {
1833         if (vif->tx.sring)
1834                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
1835                                         vif->tx.sring);
1836         if (vif->rx.sring)
1837                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
1838                                         vif->rx.sring);
1839 }
1840
1841 int xen_netbk_map_frontend_rings(struct xenvif *vif,
1842                                  grant_ref_t tx_ring_ref,
1843                                  grant_ref_t rx_ring_ref)
1844 {
1845         void *addr;
1846         struct xen_netif_tx_sring *txs;
1847         struct xen_netif_rx_sring *rxs;
1848
1849         int err = -ENOMEM;
1850
1851         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
1852                                      tx_ring_ref, &addr);
1853         if (err)
1854                 goto err;
1855
1856         txs = (struct xen_netif_tx_sring *)addr;
1857         BACK_RING_INIT(&vif->tx, txs, PAGE_SIZE);
1858
1859         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
1860                                      rx_ring_ref, &addr);
1861         if (err)
1862                 goto err;
1863
1864         rxs = (struct xen_netif_rx_sring *)addr;
1865         BACK_RING_INIT(&vif->rx, rxs, PAGE_SIZE);
1866
1867         vif->rx_req_cons_peek = 0;
1868
1869         return 0;
1870
1871 err:
1872         xen_netbk_unmap_frontend_rings(vif);
1873         return err;
1874 }
1875
1876 static int __init netback_init(void)
1877 {
1878         int i;
1879         int rc = 0;
1880         int group;
1881
1882         if (!xen_domain())
1883                 return -ENODEV;
1884
1885         if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
1886                 printk(KERN_INFO
1887                        "xen-netback: fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
1888                        fatal_skb_slots, XEN_NETBK_LEGACY_SLOTS_MAX);
1889                 fatal_skb_slots = XEN_NETBK_LEGACY_SLOTS_MAX;
1890         }
1891
1892         xen_netbk_group_nr = num_online_cpus();
1893         xen_netbk = vzalloc(sizeof(struct xen_netbk) * xen_netbk_group_nr);
1894         if (!xen_netbk)
1895                 return -ENOMEM;
1896
1897         for (group = 0; group < xen_netbk_group_nr; group++) {
1898                 struct xen_netbk *netbk = &xen_netbk[group];
1899                 skb_queue_head_init(&netbk->rx_queue);
1900                 skb_queue_head_init(&netbk->tx_queue);
1901
1902                 init_timer(&netbk->net_timer);
1903                 netbk->net_timer.data = (unsigned long)netbk;
1904                 netbk->net_timer.function = xen_netbk_alarm;
1905
1906                 netbk->pending_cons = 0;
1907                 netbk->pending_prod = MAX_PENDING_REQS;
1908                 for (i = 0; i < MAX_PENDING_REQS; i++)
1909                         netbk->pending_ring[i] = i;
1910
1911                 init_waitqueue_head(&netbk->wq);
1912                 netbk->task = kthread_create(xen_netbk_kthread,
1913                                              (void *)netbk,
1914                                              "netback/%u", group);
1915
1916                 if (IS_ERR(netbk->task)) {
1917                         printk(KERN_ALERT "kthread_create() fails at netback\n");
1918                         del_timer(&netbk->net_timer);
1919                         rc = PTR_ERR(netbk->task);
1920                         goto failed_init;
1921                 }
1922
1923                 kthread_bind(netbk->task, group);
1924
1925                 INIT_LIST_HEAD(&netbk->net_schedule_list);
1926
1927                 spin_lock_init(&netbk->net_schedule_list_lock);
1928
1929                 atomic_set(&netbk->netfront_count, 0);
1930
1931                 wake_up_process(netbk->task);
1932         }
1933
1934         rc = xenvif_xenbus_init();
1935         if (rc)
1936                 goto failed_init;
1937
1938         return 0;
1939
1940 failed_init:
1941         while (--group >= 0) {
1942                 struct xen_netbk *netbk = &xen_netbk[group];
1943                 for (i = 0; i < MAX_PENDING_REQS; i++) {
1944                         if (netbk->mmap_pages[i])
1945                                 __free_page(netbk->mmap_pages[i]);
1946                 }
1947                 del_timer(&netbk->net_timer);
1948                 kthread_stop(netbk->task);
1949         }
1950         vfree(xen_netbk);
1951         return rc;
1952
1953 }
1954
1955 module_init(netback_init);
1956
1957 MODULE_LICENSE("Dual BSD/GPL");
1958 MODULE_ALIAS("xen-backend:vif");