From: Andrew Morton <akpm@osdl.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org,
davej@redhat.com, tglx@linutronix.de, drepper@redhat.com
Subject: Re: [patch] pi-futex: futex_wake() lockup fix
Date: Sat, 1 Jul 2006 00:23:05 -0700 [thread overview]
Message-ID: <20060701002305.7b6b78a4.akpm@osdl.org> (raw)
In-Reply-To: <20060701070746.GA22457@elte.hu>
On Sat, 1 Jul 2006 09:07:46 +0200
Ingo Molnar <mingo@elte.hu> wrote:
> Subject: pi-futex: futex_wake() lockup fix
> From: Ingo Molnar <mingo@elte.hu>
>
> fix futex_wake() exit condition bug when handling the robust-list with
> PI futexes on them.
>
> (reported by Ulrich Drepper, debugged by the lock validator.)
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
> kernel/futex.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> Index: linux/kernel/futex.c
> ===================================================================
> --- linux.orig/kernel/futex.c
> +++ linux/kernel/futex.c
> @@ -646,8 +646,10 @@ static int futex_wake(u32 __user *uaddr,
>
> list_for_each_entry_safe(this, next, head, list) {
> if (match_futex (&this->key, &key)) {
> - if (this->pi_state)
> - return -EINVAL;
> + if (this->pi_state) {
> + ret = -EINVAL;
> + break;
> + }
> wake_futex(this);
> if (++ret >= nr_wake)
> break;
Well that was rather a howler.
How did the lock validator help in identifying this?
next prev parent reply other threads:[~2006-07-01 7:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-01 7:07 [patch] pi-futex: futex_wake() lockup fix Ingo Molnar
2006-07-01 7:23 ` Andrew Morton [this message]
2006-07-01 7:25 ` Ingo Molnar
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