On Mon, 2006-06-12 at 12:36 -0400, Chuck Ebbert wrote:
> I already applied this, which should keep it from freezing and
> will print a warning, so I will apply your patch and then check
> the log every time pppd exits.
Your debug output seems like a good idea for catching
the mechanism of reentrance on flush_to_ldisc (if it
is happening at all).
My reading of the workqueue code is that the work
function can run in parallel on a multiple CPU
system. The default workqueue has multiple, per
CPU queues, and the pending bit for the
work item is cleared before execution. This would
allow the work item to be requeued for another CPU
while the function is executing.
(If I'm wrong, I would be happy to be told why)
Anyways, if I can impose on you to use this version
with debug output, it would help clarify this.
If the DONT_FLIP debug output happens too often and
fills you syslog, comment out that part.
--- a/include/linux/tty.h 2006-06-09 09:33:16.000000000 -0500
+++ b/include/linux/tty.h 2006-06-12 09:22:10.000000000 -0500
@@ -267,6 +267,7 @@ 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))
--- a/drivers/char/tty_io.c 2006-06-12 12:54:37.000000000 -0500
+++ b/drivers/char/tty_io.c 2006-06-12 12:54:54.000000000 -0500
@@ -2786,9 +2786,12 @@ static void flush_to_ldisc(void *private
return;
if (test_bit(TTY_DONT_FLIP, &tty->flags)) {
- /*
- * Do it after the next timer tick:
- */
+ printk(KERN_ERR"flush_to_ldisc - TTY_DONT_FLIP set\n");
+ schedule_delayed_work(&tty->buf.work, 1);
+ goto out;
+ }
+ if (test_and_set_bit(TTY_FLUSHING, &tty->flags)) {
+ printk(KERN_ERR"flush_to_ldisc - TTY_FLUSHING set, low_latency=%d\n", tty->low_latency);
schedule_delayed_work(&tty->buf.work, 1);
goto out;
}
@@ -2810,6 +2813,7 @@ 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);
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
