From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, Al Viro <viro@ZenIV.linux.org.uk>,
Bart Van Assche <bvanassche@acm.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Neil Brown <neilb@suse.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock()
Date: Fri, 2 Sep 2016 14:06:43 +0200 [thread overview]
Message-ID: <20160902120642.GC26495@redhat.com> (raw)
In-Reply-To: <20160901221743.GJ10168@twins.programming.kicks-ass.net>
On 09/02, Peter Zijlstra wrote:
>
> FWIW, the way the mutex code avoids this issue is by doing the
> signal_pending test while holding the q->lock, that way its exclusive
> with wakeup.
And __wait_event_interruptible_locked() too.
BTW it is buggy anyway, it needs the
- __add_wait_queue_tail(&(wq), &__wait);
+ if (exclusive)
+ __add_wait_queue_tail(&(wq), &__wait);
+ else
+ __add_wait_queue((&(wq), &__wait);
and in fact it should use __add_wait_queue_exclusive() so that we
can remove another "if (exclusive)" but this is off-topic.
Yes, I considered this option, but to me the addtional finish_wait()
looks simpler.
And, if you agree with this change I will try to change __wait_event()
as well and kill abort_exclusive_wait().
And in this case we certainly do not want to check the "condition" with
q->lock held, because this would mean that "condition" won't be able to
take this lock.
Oleg.
next prev parent reply other threads:[~2016-09-02 12:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-26 12:44 [PATCH 0/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Oleg Nesterov
2016-08-26 12:45 ` [PATCH 1/2] " Oleg Nesterov
2016-09-01 11:39 ` Peter Zijlstra
2016-09-01 17:26 ` Oleg Nesterov
2016-09-01 18:09 ` Peter Zijlstra
2016-08-26 12:45 ` [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Oleg Nesterov
2016-08-26 12:47 ` Oleg Nesterov
2016-09-01 19:01 ` Peter Zijlstra
2016-09-01 19:08 ` Peter Zijlstra
2016-09-02 12:06 ` Oleg Nesterov
2016-09-01 22:17 ` Peter Zijlstra
2016-09-02 12:06 ` Oleg Nesterov [this message]
2016-09-02 13:20 ` Peter Zijlstra
2016-09-02 12:06 ` Oleg Nesterov
2016-09-01 11:03 ` [PATCH 0/2] sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up() Peter Zijlstra
[not found] <00e501d201cf$7bfecd40$73fc67c0$@alibaba-inc.com>
2016-08-29 8:41 ` [PATCH 2/2] sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock() Hillf Danton
2016-08-29 13:48 ` Oleg Nesterov
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=20160902120642.GC26495@redhat.com \
--to=oleg@redhat.com \
--cc=bvanassche@acm.org \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=neilb@suse.de \
--cc=peterz@infradead.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@ZenIV.linux.org.uk \
/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;
as well as URLs for NNTP newsgroup(s).