From: Oleg Nesterov <oleg@redhat.com>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
"Lai, Yi" <yi1.lai@linux.intel.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
Adrian Hunter <adrian.hunter@intel.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Daniel Bristot de Oliveira <bristot@kernel.org>,
Ian Rogers <irogers@google.com>, Ingo Molnar <mingo@redhat.com>,
Jiri Olsa <jolsa@kernel.org>,
Kan Liang <kan.liang@linux.intel.com>,
Marco Elver <elver@google.com>,
Mark Rutland <mark.rutland@arm.com>,
Namhyung Kim <namhyung@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
yi1.lai@intel.com, syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH v4 2/6] perf: Enqueue SIGTRAP always via task_work.
Date: Mon, 16 Dec 2024 20:19:37 +0100 [thread overview]
Message-ID: <20241216191937.GC374@redhat.com> (raw)
In-Reply-To: <Z1y6vSznjbCwAvn1@pavilion.home>
On 12/13, Frederic Weisbecker wrote:
>
> So which way do you prefer do solve the initial problem?
Ah. please do what you think/feel is right.
I can't suggest a better fix anyway.
> > > > do {
> > > > - next = work->next;
> > > > + next = READ_ONCE(work->next);
> > > > work->func(work);
> > > > work = next;
> > > > cond_resched();
> > > >
> > > > Perhaps it makes sense before the patch from Sebastian even if that patch
> > > > removes this do/while loop ?
> > >
> > > Hmm, can work->next be modified concurrently here?
> >
> > work->func(work) can, say, do kfree(work) or do another task_work_add(X,
> > work).
>
> Right but then isn't it serialized program order, from the compiler point of view?
Hmm, indeed, you are right. In this case the compiler can't assume it can
"defer" work->next. Thanks for correcting me!
Oleg.
next prev parent reply other threads:[~2024-12-16 19:20 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-24 15:15 [PATCH v4 0/6] perf: Make SIGTRAP and __perf_pending_irq() work on RT Sebastian Andrzej Siewior
2024-06-24 15:15 ` [PATCH v4 1/6] perf: Move irq_work_queue() where the event is prepared Sebastian Andrzej Siewior
2024-06-24 15:15 ` [PATCH v4 2/6] perf: Enqueue SIGTRAP always via task_work Sebastian Andrzej Siewior
2024-07-01 12:28 ` Peter Zijlstra
2024-07-01 13:27 ` Sebastian Andrzej Siewior
2024-07-02 9:01 ` Peter Zijlstra
2024-10-28 8:30 ` Lai, Yi
2024-10-28 12:21 ` Frederic Weisbecker
2024-10-29 17:21 ` Sebastian Andrzej Siewior
2024-10-30 14:07 ` Sebastian Andrzej Siewior
2024-10-30 15:46 ` Frederic Weisbecker
2024-11-07 14:46 ` Sebastian Andrzej Siewior
2024-11-08 13:11 ` Frederic Weisbecker
2024-11-08 19:08 ` Oleg Nesterov
2024-11-08 22:26 ` Frederic Weisbecker
2024-11-11 12:08 ` Sebastian Andrzej Siewior
2024-12-04 3:02 ` Lai, Yi
2024-12-04 13:48 ` Oleg Nesterov
2024-12-05 0:19 ` Frederic Weisbecker
2024-12-05 9:20 ` Oleg Nesterov
2024-12-05 10:05 ` Frederic Weisbecker
2024-12-05 10:28 ` Oleg Nesterov
2024-12-13 22:52 ` Frederic Weisbecker
2024-12-16 19:19 ` Oleg Nesterov [this message]
2024-06-24 15:15 ` [PATCH v4 3/6] perf: Shrink the size of the recursion counter Sebastian Andrzej Siewior
2024-07-01 12:31 ` Peter Zijlstra
2024-07-01 12:56 ` Sebastian Andrzej Siewior
2024-07-01 13:10 ` Peter Zijlstra
2024-06-24 15:15 ` [PATCH v4 4/6] perf: Move swevent_htable::recursion into task_struct Sebastian Andrzej Siewior
2024-06-24 15:15 ` [PATCH v4 5/6] perf: Don't disable preemption in perf_pending_task() Sebastian Andrzej Siewior
2024-06-24 15:15 ` [PATCH v4 6/6] perf: Split __perf_pending_irq() out of perf_pending_irq() Sebastian Andrzej Siewior
2024-06-25 13:42 ` [PATCH v4 0/6] perf: Make SIGTRAP and __perf_pending_irq() work on RT Marco Elver
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=20241216191937.GC374@redhat.com \
--to=oleg@redhat.com \
--cc=acme@kernel.org \
--cc=acme@redhat.com \
--cc=adrian.hunter@intel.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=bigeasy@linutronix.de \
--cc=bristot@kernel.org \
--cc=elver@google.com \
--cc=frederic@kernel.org \
--cc=irogers@google.com \
--cc=jolsa@kernel.org \
--cc=kan.liang@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=syzkaller-bugs@googlegroups.com \
--cc=tglx@linutronix.de \
--cc=yi1.lai@intel.com \
--cc=yi1.lai@linux.intel.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