From: Peter Zijlstra <peterz@infradead.org>
To: riel@redhat.com
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
prarit@redhat.com, oleg@redhat.com, sgruszka@redhat.com
Subject: Re: [PATCH -tip 0/2] fix lock inversion in lockless sys_times()
Date: Sun, 14 Sep 2014 11:22:00 +0200 [thread overview]
Message-ID: <20140914092200.GQ346@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <1410527535-9814-1-git-send-email-riel@redhat.com>
On Fri, Sep 12, 2014 at 09:12:13AM -0400, riel@redhat.com wrote:
> The sig->stats_lock nests inside the tasklist_lock and the
> sighand->siglock in __exit_signal and wait_task_zombie.
>
> However, both of those locks can be taken from irq context,
> which means we need to use the interrupt safe variant of
> read_seqbegin_or_lock. This blocks interrupts when the "lock"
> branch is taken (seq is odd), preventing the lock inversion.
>
> On the first (lockless) pass through the loop, irqs are not
> blocked.
>
> This fixes the lockdep complaints that Stanislaw reported.
>
Thanks Rik
prev parent reply other threads:[~2014-09-14 9:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-12 13:12 [PATCH -tip 0/2] fix lock inversion in lockless sys_times() riel
2014-09-12 13:12 ` [PATCH -tip 1/2] seqlock: add irqsave variant of read_seqbegin_or_lock riel
2014-09-19 11:44 ` [tip:sched/core] seqlock: Add irqsave variant of read_seqbegin_or_lock() tip-bot for Rik van Riel
2014-09-12 13:12 ` [PATCH -tip 2/2] sched,time: fix lock inversion in thread_group_cputime riel
2014-09-19 11:44 ` [tip:sched/core] sched, time: Fix lock inversion in thread_group_cputime() tip-bot for Rik van Riel
2014-09-14 9:22 ` Peter Zijlstra [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140914092200.GQ346@worktop.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=prarit@redhat.com \
--cc=riel@redhat.com \
--cc=sgruszka@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox