This is a note to let you know that I've just added the patch titled
hvc_console: Fix race between hvc_close and hvc_remove
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
hvc_console-fix-race-between-hvc_close-and-hvc_remove-2.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <[email protected]> know about it.
>From 320718ee074acce5ffced6506cb51af1388942aa Mon Sep 17 00:00:00 2001
From: Anton Blanchard <[email protected]>
Date: Tue, 6 Apr 2010 21:42:38 +1000
Subject: hvc_console: Fix race between hvc_close and hvc_remove
From: Anton Blanchard <[email protected]>
commit 320718ee074acce5ffced6506cb51af1388942aa upstream.
I don't claim to understand the tty layer, but it seems like hvc_open and
hvc_close should be balanced in their kref reference counting.
Right now we get a kref every call to hvc_open:
if (hp->count++ > 0) {
tty_kref_get(tty); <----- here
spin_unlock_irqrestore(&hp->lock, flags);
hvc_kick();
return 0;
} /* else count == 0 */
tty->driver_data = hp;
hp->tty = tty_kref_get(tty); <------ or here if hp->count was 0
But hvc_close has:
tty_kref_get(tty);
if (--hp->count == 0) {
...
/* Put the ref obtained in hvc_open() */
tty_kref_put(tty);
...
}
tty_kref_put(tty);
Since the outside kref get/put balance we only do a single kref_put when
count reaches 0.
The patch below changes things to call tty_kref_put once for every
hvc_close call, and with that my machine boots fine.
Signed-off-by: Anton Blanchard <[email protected]>
Acked-by: Amit Shah <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/char/hvc_console.c | 4 ----
1 file changed, 4 deletions(-)
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -367,16 +367,12 @@ static void hvc_close(struct tty_struct
hp = tty->driver_data;
spin_lock_irqsave(&hp->lock, flags);
- tty_kref_get(tty);
if (--hp->count == 0) {
/* We are done with the tty pointer now. */
hp->tty = NULL;
spin_unlock_irqrestore(&hp->lock, flags);
- /* Put the ref obtained in hvc_open() */
- tty_kref_put(tty);
-
if (hp->ops->notifier_del)
hp->ops->notifier_del(hp, hp->data);
Patches currently in longterm-queue-2.6.32 which might be from [email protected]
are
_______________________________________________
stable mailing list
[email protected]
http://linux.kernel.org/mailman/listinfo/stable
