BACKPORT: dmaengine: core: expose max burst capability to clients

[firefly-linux-kernel-4.4.55.git] / kernel / futex.c

diff --git a/kernel/futex.c b/kernel/futex.c
index 684d7549825a4300ced2002a3fbec0a5698a18d1..9d8163afd87ca7605ef85d2ca64d3c4521838fae 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1244,10 +1244,20 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
        if (unlikely(should_fail_futex(true)))
                ret = -EFAULT;
 
-       if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))
+       if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) {
                ret = -EFAULT;
-       else if (curval != uval)
-               ret = -EINVAL;
+       } else if (curval != uval) {
+               /*
+                * If a unconditional UNLOCK_PI operation (user space did not
+                * try the TID->0 transition) raced with a waiter setting the
+                * FUTEX_WAITERS flag between get_user() and locking the hash
+                * bucket lock, retry the operation.
+                */
+               if ((FUTEX_TID_MASK & curval) == uval)
+                       ret = -EAGAIN;
+               else
+                       ret = -EINVAL;
+       }
        if (ret) {
                raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
                return ret;
@@ -1474,8 +1484,8 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
        if (likely(&hb1->chain != &hb2->chain)) {
                plist_del(&q->list, &hb1->chain);
                hb_waiters_dec(hb1);
-               plist_add(&q->list, &hb2->chain);
                hb_waiters_inc(hb2);
+               plist_add(&q->list, &hb2->chain);
                q->lock_ptr = &hb2->lock;
        }
        get_futex_key_refs(key2);
@@ -2537,6 +2547,15 @@ retry:
                 */
                if (ret == -EFAULT)
                        goto pi_faulted;
+               /*
+                * A unconditional UNLOCK_PI op raced against a waiter
+                * setting the FUTEX_WAITERS bit. Try again.
+                */
+               if (ret == -EAGAIN) {
+                       spin_unlock(&hb->lock);
+                       put_futex_key(&key);
+                       goto retry;
+               }
                /*
                 * wake_futex_pi has detected invalid state. Tell user
                 * space.
@@ -2755,6 +2774,11 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
                if (q.pi_state && (q.pi_state->owner != current)) {
                        spin_lock(q.lock_ptr);
                        ret = fixup_pi_state_owner(uaddr2, &q, current);
+                       /*
+                        * Drop the reference to the pi state which
+                        * the requeue_pi() code acquired for us.
+                        */
+                       free_pi_state(q.pi_state);
                        spin_unlock(q.lock_ptr);
                }
        } else {
@@ -2881,7 +2905,7 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
        }
 
        ret = -EPERM;
-       if (!ptrace_may_access(p, PTRACE_MODE_READ))
+       if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS))
                goto err_unlock;
 
        head = p->robust_list;