From: Oleg Nesterov <oleg@redhat.com>
To: Mandeep Singh Baines <msb@chromium.org>
Cc: linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH 3/5] coredump: cleanup the waiting for coredump_finish code
Date: Fri, 15 Feb 2013 15:53:23 +0100 [thread overview]
Message-ID: <20130215145323.GA30829@redhat.com> (raw)
In-Reply-To: <1360885096-21207-3-git-send-email-msb@chromium.org>
On 02/14, Mandeep Singh Baines wrote:
>
> Replace the for loop with a simple if.
Why?
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -479,12 +479,9 @@ static void exit_mm(struct task_struct * tsk)
> if (atomic_dec_and_test(&core_state->nr_threads))
> complete(&core_state->startup);
>
> - for (;;) {
> - set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> - if (!self.task) /* see coredump_finish() */
> - break;
> + set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> + if (self.task) /* see coredump_finish() */
> schedule();
> - }
If you think we should not worry about spurious wakeups you can simplify
this code even more, you do not need mb() to set TASK_UNINTERRUPTIBLE
(just move it before dec_and_test), you do not need "if (self.task)",
you do not need __set_task_state(tsk, TASK_RUNNING).
But I think we should always worry, so why?
Oleg.
next prev parent reply other threads:[~2013-02-15 14:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-14 23:38 [PATCH 1/5] vfork: don't freezer_count() for in-kernel users of CLONE_VFORK Mandeep Singh Baines
2013-02-14 23:38 ` [PATCH 2/5] lockdep: check that no locks held at freeze time Mandeep Singh Baines
2013-02-15 11:16 ` Ingo Molnar
2013-02-15 15:44 ` Oleg Nesterov
2013-02-14 23:38 ` [PATCH 3/5] coredump: cleanup the waiting for coredump_finish code Mandeep Singh Baines
2013-02-15 14:53 ` Oleg Nesterov [this message]
2013-02-15 23:30 ` Andrew Morton
2013-02-14 23:38 ` [PATCH 4/5] coredump: use a freezable_schedule for the coredump_finish wait Mandeep Singh Baines
2013-02-14 23:38 ` [PATCH 5/5] coredump: abort core dump piping only due to a fatal signal Mandeep Singh Baines
2013-02-15 15:01 ` Oleg Nesterov
2013-02-16 1:20 ` Mandeep Singh Baines
2013-02-16 17:05 ` Oleg Nesterov
2013-02-15 23:25 ` Andrew Morton
2013-02-16 0:09 ` [PATCH v3] coredump: ignore non-fatal signals when core dumping to a pipe Mandeep Singh Baines
2013-02-16 0:57 ` [PATCH v4] " Mandeep Singh Baines
2013-02-15 15:28 ` [PATCH 1/5] vfork: don't freezer_count() for in-kernel users of CLONE_VFORK Oleg Nesterov
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