In-Reply-To: <[email protected]>
On Sat, 22 Jul 2006 09:04:44 -0500, Paul Fulghum wrote:
> That confirms my thoughts on what went wrong:
> multiple copies of the queued work (flush_to_ldisc)
> running in parallel and corrupting the free buffer list.
>
> A cleaner fix for this is already
> in the 2.6.18 rc series.
The cleaner fix looks more intrusive, though.
Is this simpler change (what I'm running but without the warning
messages) the preferred fix for -stable?
From: Paul Fulghum <[email protected]>
Serialize flush_to_ldisc() per-device. Fixes free list corruption
that causes lockup on SMP systems.
Signed-off-by: Paul Fulghum <[email protected]>
Acked-by: Chuck Ebbert <[email protected]>
--- 2.6.16.20-d4.orig/include/linux/tty.h
+++ 2.6.16.20-d4/include/linux/tty.h
@@ -266,6 +266,7 @@ struct tty_struct {
#define TTY_PTY_LOCK 16 /* pty private */
#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
#define TTY_HUPPED 18 /* Post driver->hangup() */
+#define TTY_FLUSHING 19 /* Flushing tty buffers to line discipline */
#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
--- 2.6.16.20-d4.orig/drivers/char/tty_io.c
+++ 2.6.16.20-d4/drivers/char/tty_io.c
@@ -2780,10 +2780,8 @@ 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:
- */
+ if (test_bit(TTY_DONT_FLIP, &tty->flags) ||
+ test_and_set_bit(TTY_FLUSHING, &tty->flags)) {
schedule_delayed_work(&tty->buf.work, 1);
goto out;
}
@@ -2805,6 +2803,7 @@ static void flush_to_ldisc(void *private
tty_buffer_free(tty, tbuf);
}
spin_unlock_irqrestore(&tty->buf.lock, flags);
+ clear_bit(TTY_FLUSHING, &tty->flags);
out:
tty_ldisc_deref(disc);
}
--
Chuck
-
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