lkml.org 
[lkml]   [2007]   [Sep]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] robust futex thread exit race

* Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> Hi Ingo,
> I finally found the bug that causes tst-robust8 from the glibc to fail
> on s390x. Turned out to be a common code problem with the processing of
> the robust futex list. The patch below fixes the bug for me.

good catch! A quick preliminary review of your patch indicates it's fine
- and it might be v2.6.23 material.

Acked-by: Ingo Molnar <mingo@elte.hu>

> Calling handle_futex_death in exit_robust_list for the different
> robust mutexes of a thread basically frees the mutex. Another thread
> might grab the lock immediately which updates the next pointer of the
> mutex. fetch_robust_entry over the next pointer might therefore branch
> into the robust mutex list of a different thread. This can cause two
> problems: 1) some mutexes held by the dead thread are not getting
> freed and 2) some mutexs held by a different thread are freed. The
> next point need to be read before calling handle_futex_death.

nasty race... Ulrich, Thomas, do you concur?

Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-09-30 17:23    [from the cache]
©2003-2011 Jasper Spaans