From: Steven Rostedt <rostedt@goodmis.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de
Subject: Re: [RT PATCH 1/2] timers: wakeup all timer waiters
Date: Thu, 14 Jul 2016 13:19:45 -0400 [thread overview]
Message-ID: <20160714131945.67cc8ce5@gandalf.local.home> (raw)
In-Reply-To: <e014d4ad-316f-3afe-fcac-923cd2f9a7e6@linutronix.de>
On Thu, 14 Jul 2016 19:14:58 +0200
Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:
> On 07/14/2016 06:13 PM, Steven Rostedt wrote:
> >>
> >> -# define wakeup_timer_waiters(b) wake_up(&(b)->wait_for_running_timer)
> >> +# define wakeup_timer_waiters(b) wake_up_all(&(b)->wait_for_running_timer)
> >
> > OK, I just received this patch (way after patch 2)
> >
> > I'm assuming that patch two was done such that you don't do a
> > "wake_up_all" under a spinlock.
>
> No. I pulled in new timer code in and had to redo this part of RT.
>
> While doing so I noticed that we drop the base lock during timer
> invocations and so it could be possible that we have two invocations
> of del_timer_sync() on a timer on the same "base" (one after the
> other). This is patch #1.
>
> After that I saw that we do the wake up under the base lock but there
> is no reason for it. So here is patch #2.
>
> Patch #1 is something that could happen in theory and I did not run in
> any problem.
>
OK, so patch 2 was just discovered by reviewing code?
-- Steve
next prev parent reply other threads:[~2016-07-14 17:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 16:05 [RT PATCH 1/2] timers: wakeup all timer waiters Sebastian Andrzej Siewior
2016-07-14 16:05 ` [RT PATCH 2/2] timers: wakeup all timer waiters without holding the base lock Sebastian Andrzej Siewior
2016-07-14 16:09 ` Steven Rostedt
2016-07-14 17:19 ` Sebastian Andrzej Siewior
2016-07-14 17:21 ` Steven Rostedt
2016-07-14 16:13 ` [RT PATCH 1/2] timers: wakeup all timer waiters Steven Rostedt
2016-07-14 17:14 ` Sebastian Andrzej Siewior
2016-07-14 17:19 ` Steven Rostedt [this message]
2016-07-14 18:37 ` Sebastian Andrzej Siewior
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=20160714131945.67cc8ce5@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=bigeasy@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rt-users@vger.kernel.org \
--cc=tglx@linutronix.de \
/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).