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 <[email protected]>
--- a/drivers/char/tty_io.c 2006-06-23 15:40:14.000000000 -0500
+++ b/drivers/char/tty_io.c 2006-06-23 15:39:47.000000000 -0500
@@ -2772,7 +2772,7 @@ 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;
+ struct tty_buffer *tbuf, *head;
int count;
char *char_buf;
unsigned char *flag_buf;
@@ -2782,21 +2782,33 @@ 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 (;;) {
+ 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);
-
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