1 files changed, 33 insertions, 42 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 6c79ff3030fa..a1143238feca 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -266,7 +266,6 @@ static struct tty_buffer *tty_buffer_alloc(size_t size)
         p->used = 0;
         p->size = size;
         p->next = NULL;
-        p->active = 0;
         p->commit = 0;
         p->read = 0;
         p->char_buf_ptr = (char *)(p->data);
@@ -326,10 +325,9 @@ int tty_buffer_request_room(struct tty_struct *tty, size_t size)
         /* OPTIMISATION: We could keep a per tty "zero" sized buffer to
            remove this conditional if its worth it. This would be invisible
            to the callers */
-        if ((b = tty->buf.tail) != NULL) {
+        if ((b = tty->buf.tail) != NULL)
                 left = b->size - b->used;
-                b->active = 1;
-        } else
+        else
                 left = 0;
 
         if (left < size) {
@@ -337,12 +335,10 @@ int tty_buffer_request_room(struct tty_struct *tty, size_t size)
                 if ((n = tty_buffer_find(tty, size)) != NULL) {
                         if (b != NULL) {
                                 b->next = n;
-                                b->active = 0;
                                 b->commit = b->used;
                         } else
                                 tty->buf.head = n;
                         tty->buf.tail = n;
-                        n->active = 1;
                 } else
                         size = left;
         }
@@ -403,10 +399,8 @@ void tty_schedule_flip(struct tty_struct *tty)
 {
         unsigned long flags;
         spin_lock_irqsave(&tty->buf.lock, flags);
-        if (tty->buf.tail != NULL) {
-                tty->buf.tail->active = 0;
+        if (tty->buf.tail != NULL)
                 tty->buf.tail->commit = tty->buf.tail->used;
-        }
         spin_unlock_irqrestore(&tty->buf.lock, flags);
         schedule_delayed_work(&tty->buf.work, 1);
 }
@@ -783,11 +777,8 @@ restart:
         }
 
         clear_bit(TTY_LDISC, &tty->flags);
-        clear_bit(TTY_DONT_FLIP, &tty->flags);
-        if (o_tty) {
+        if (o_tty)
                 clear_bit(TTY_LDISC, &o_tty->flags);
-                clear_bit(TTY_DONT_FLIP, &o_tty->flags);
-        }
         spin_unlock_irqrestore(&tty_ldisc_lock, flags);
 
         /*
@@ -1954,7 +1945,6 @@ static void release_dev(struct file * filp)
          * race with the set_ldisc code path.
          */
         clear_bit(TTY_LDISC, &tty->flags);
-        clear_bit(TTY_DONT_FLIP, &tty->flags);
         cancel_delayed_work(&tty->buf.work);
 
         /*
@@ -2620,10 +2610,9 @@ int tty_ioctl(struct inode * inode, struct file * file,
                         tty->driver->break_ctl(tty, 0);
                         return 0;
                 case TCSBRK:   /* SVID version: non-zero arg --> no break */
-                        /*
-                         * XXX is the above comment correct, or the
-                         * code below correct?  Is this ioctl used at
-                         * all by anyone?
+                        /* non-zero arg means wait for all output data
+                         * to be sent (performed above) but don't send break.
+                         * This is used by the tcdrain() termios function.
                          */
                         if (!arg)
                                 return send_break(tty, 250);
@@ -2775,8 +2764,7 @@ static void flush_to_ldisc(void *private_)
         struct tty_struct *tty = (struct tty_struct *) private_;
         unsigned long   flags;
         struct tty_ldisc *disc;
-        struct tty_buffer *tbuf;
-        int count;
+        struct tty_buffer *tbuf, *head;
         char *char_buf;
         unsigned char *flag_buf;
 
@@ -2784,32 +2772,37 @@ static void flush_to_ldisc(void *private_)
         if (disc == NULL)       /*  !TTY_LDISC */
                 return;
 
-        if (test_bit(TTY_DONT_FLIP, &tty->flags)) {
-                /*
-                 * Do it after the next timer tick:
-                 */
-                schedule_delayed_work(&tty->buf.work, 1);
-                goto out;
-        }
         spin_lock_irqsave(&tty->buf.lock, flags);
-        while((tbuf = tty->buf.head) != NULL) {
-                while ((count = tbuf->commit - tbuf->read) != 0) {
-                        char_buf = tbuf->char_buf_ptr + tbuf->read;
-                        flag_buf = tbuf->flag_buf_ptr + tbuf->read;
-                        tbuf->read += count;
+        head = tty->buf.head;
+        if (head != NULL) {
+                tty->buf.head = NULL;
+                for (;;) {
+                        int count = head->commit - head->read;
+                        if (!count) {
+                                if (head->next == NULL)
+                                        break;
+                                tbuf = head;
+                                head = head->next;
+                                tty_buffer_free(tty, tbuf);
+                                continue;
+                        }
+                        if (!tty->receive_room) {
+                                schedule_delayed_work(&tty->buf.work, 1);
+                                break;
+                        }
+                        if (count > tty->receive_room)
+                                count = tty->receive_room;
+                        char_buf = head->char_buf_ptr + head->read;
+                        flag_buf = head->flag_buf_ptr + head->read;
+                        head->read += count;
                         spin_unlock_irqrestore(&tty->buf.lock, flags);
                         disc->receive_buf(tty, char_buf, flag_buf, count);
                         spin_lock_irqsave(&tty->buf.lock, flags);
                 }
-                if (tbuf->active)
-                        break;
-                tty->buf.head = tbuf->next;
-                if (tty->buf.head == NULL)
-                        tty->buf.tail = NULL;
-                tty_buffer_free(tty, tbuf);
+                tty->buf.head = head;
         }
         spin_unlock_irqrestore(&tty->buf.lock, flags);
-out:
+
         tty_ldisc_deref(disc);
 }
 
@@ -2902,10 +2895,8 @@ void tty_flip_buffer_push(struct tty_struct *tty)
 {
         unsigned long flags;
         spin_lock_irqsave(&tty->buf.lock, flags);
-        if (tty->buf.tail != NULL) {
-                tty->buf.tail->active = 0;
+        if (tty->buf.tail != NULL)
                 tty->buf.tail->commit = tty->buf.tail->used;
-        }
         spin_unlock_irqrestore(&tty->buf.lock, flags);
 
         if (tty->low_latency)