X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=drivers%2Ftty%2Fn_tty.c;h=84e71bd19082e07a5a819346debffef47fc92bd9;hb=79ae01aa89b569ed599d1263eb26c6b98f039c27;hp=ed776149261ea1022fc0586ce3be200967ec4c0b;hpb=a5e90b1b075f89f084047628d4ef181aded0bbfb;p=firefly-linux-kernel-4.4.55.git

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ed776149261e..84e71bd19082 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -258,16 +258,13 @@ static void n_tty_check_throttle(struct tty_struct *tty)
 
 static void n_tty_check_unthrottle(struct tty_struct *tty)
 {
-	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
-	    tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
+	if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
 		if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
 			return;
 		if (!tty->count)
 			return;
 		n_tty_kick_worker(tty);
-		n_tty_write_wakeup(tty->link);
-		if (waitqueue_active(&tty->link->write_wait))
-			wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
+		tty_wakeup(tty->link);
 		return;
 	}
 
@@ -1958,18 +1955,6 @@ static inline int input_available_p(struct tty_struct *tty, int poll)
 		return ldata->commit_head - ldata->read_tail >= amt;
 }
 
-static inline int check_other_done(struct tty_struct *tty)
-{
-	int done = test_bit(TTY_OTHER_DONE, &tty->flags);
-	if (done) {
-		/* paired with cmpxchg() in check_other_closed(); ensures
-		 * read buffer head index is not stale
-		 */
-		smp_mb__after_atomic();
-	}
-	return done;
-}
-
 /**
  *	copy_from_read_buf	-	copy read data directly
  *	@tty: terminal device
@@ -2054,13 +2039,13 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	size_t eol;
 	size_t tail;
 	int ret, found = 0;
-	bool eof_push = 0;
 
 	/* N.B. avoid overrun if nr == 0 */
-	n = min(*nr, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
-	if (!n)
+	if (!*nr)
 		return 0;
 
+	n = min(*nr + 1, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
+
 	tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
 	size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
 
@@ -2081,12 +2066,11 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	n = eol - tail;
 	if (n > N_TTY_BUF_SIZE)
 		n += N_TTY_BUF_SIZE;
-	n += found;
-	c = n;
+	c = n + found;
 
-	if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
-		n--;
-		eof_push = !n && ldata->read_tail != ldata->line_start;
+	if (!found || read_buf(ldata, eol) != __DISABLED_CHAR) {
+		c = min(*nr, c);
+		n = c;
 	}
 
 	n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
@@ -2116,7 +2100,7 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 			ldata->push = 0;
 		tty_audit_push(tty);
 	}
-	return eof_push ? -EAGAIN : 0;
+	return 0;
 }
 
 extern ssize_t redirected_tty_write(struct file *, const char __user *,
@@ -2175,7 +2159,7 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 	struct n_tty_data *ldata = tty->disc_data;
 	unsigned char __user *b = buf;
 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
-	int c, done;
+	int c;
 	int minimum, time;
 	ssize_t retval = 0;
 	long timeout;
@@ -2243,40 +2227,40 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 		    ((minimum - (b - buf)) >= 1))
 			ldata->minimum_to_wake = (minimum - (b - buf));
 
-		done = check_other_done(tty);
-
 		if (!input_available_p(tty, 0)) {
-			if (done) {
-				retval = -EIO;
-				break;
-			}
-			if (tty_hung_up_p(file))
-				break;
-			if (!timeout)
-				break;
-			if (file->f_flags & O_NONBLOCK) {
-				retval = -EAGAIN;
-				break;
-			}
-			if (signal_pending(current)) {
-				retval = -ERESTARTSYS;
-				break;
-			}
 			up_read(&tty->termios_rwsem);
+			tty_buffer_flush_work(tty->port);
+			down_read(&tty->termios_rwsem);
+			if (!input_available_p(tty, 0)) {
+				if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
+					retval = -EIO;
+					break;
+				}
+				if (tty_hung_up_p(file))
+					break;
+				if (!timeout)
+					break;
+				if (file->f_flags & O_NONBLOCK) {
+					retval = -EAGAIN;
+					break;
+				}
+				if (signal_pending(current)) {
+					retval = -ERESTARTSYS;
+					break;
+				}
+				up_read(&tty->termios_rwsem);
 
-			timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
-					     timeout);
+				timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
+						timeout);
 
-			down_read(&tty->termios_rwsem);
-			continue;
+				down_read(&tty->termios_rwsem);
+				continue;
+			}
 		}
 
 		if (ldata->icanon && !L_EXTPROC(tty)) {
 			retval = canon_copy_from_read_buf(tty, &b, &nr);
-			if (retval == -EAGAIN) {
-				retval = 0;
-				continue;
-			} else if (retval)
+			if (retval)
 				break;
 		} else {
 			int uncopied;
@@ -2453,12 +2437,17 @@ static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
 
 	poll_wait(file, &tty->read_wait, wait);
 	poll_wait(file, &tty->write_wait, wait);
-	if (check_other_done(tty))
-		mask |= POLLHUP;
 	if (input_available_p(tty, 1))
 		mask |= POLLIN | POLLRDNORM;
+	else {
+		tty_buffer_flush_work(tty->port);
+		if (input_available_p(tty, 1))
+			mask |= POLLIN | POLLRDNORM;
+	}
 	if (tty->packet && tty->link->ctrl_status)
 		mask |= POLLPRI | POLLIN | POLLRDNORM;
+	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+		mask |= POLLHUP;
 	if (tty_hung_up_p(file))
 		mask |= POLLHUP;
 	if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {