From: Paul Fulghum Date: Wed, 28 Jun 2006 11:26:48 +0000 (-0700) Subject: [PATCH] add receive_room flow control to flush_to_ldisc X-Git-Tag: v2.6.18-rc1~449 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=2c3bb20f46709a0adfa7ea408013edbcab945d5a;p=linux-2.6-omap-h63xx.git [PATCH] add receive_room flow control to flush_to_ldisc Flush data serially to line discipline in blocks no larger than tty->receive_room to avoid losing data if line discipline is busy (such as N_TTY operating at high speed on heavily loaded system) or does not accept data in large blocks (such as N_MOUSE). Signed-off-by: Paul Fulghum Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index b846d87f2b5..1f03ebf165d 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -2771,8 +2771,7 @@ 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; @@ -2781,21 +2780,33 @@ static void flush_to_ldisc(void *private_) return; 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);