All of lore.kernel.org
 help / color / mirror / Atom feed
From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, tglx@linutronix.de,
	linux-kernel@vger.kernel.org, will.deacon@arm.com,
	mpe@ellerman.id.au, bigeasy@linutronix.de, gkohli@codeaurora.org,
	neeraju@codeaurora.org
Subject: Re: [PATCH 2/2] sched: Introduce set_special_state()
Date: Tue, 1 May 2018 15:59:24 +0200	[thread overview]
Message-ID: <20180501135924.GA12696@redhat.com> (raw)
In-Reply-To: <20180501095054.GD12235@hirez.programming.kicks-ass.net>

On 05/01, Peter Zijlstra wrote:
>
> The only code I found that seems to care is ptrace_attach(), where we
> wait for JOBCTL_TRAPPING to get cleared. That same function has a
> comment about hiding the STOPPED -> RUNNING -> TRACED transition. So I'm
> assuming it needs to observe TRACED if it observes !TRAPPING.

Yes, exactly.

> But I don't think there's enough barriers on that end to guarantee this.
> Any ->state load after wait_on_bit() is, afact, free to have happened
> before the ->jobctl load.

do_wait() does set_current_state() before it checks ->state or anything else.

Oleg.

  reply	other threads:[~2018-05-01 13:59 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30 14:17 [PATCH 0/2] sched,kthread: Fix TASK_PARKED and special sleep states Peter Zijlstra
2018-04-30 14:17 ` [PATCH 1/2] kthread: Fix kthread_parkme() wait-loop Peter Zijlstra
2018-04-30 14:17 ` [PATCH 2/2] sched: Introduce set_special_state() Peter Zijlstra
2018-04-30 16:45   ` Oleg Nesterov
2018-04-30 19:40     ` Peter Zijlstra
2018-05-01  9:50       ` Peter Zijlstra
2018-05-01 13:59         ` Oleg Nesterov [this message]
2018-05-01 14:22           ` Peter Zijlstra
2018-05-01 15:10             ` 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=20180501135924.GA12696@redhat.com \
    --to=oleg@redhat.com \
    --cc=bigeasy@linutronix.de \
    --cc=gkohli@codeaurora.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=mpe@ellerman.id.au \
    --cc=neeraju@codeaurora.org \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=will.deacon@arm.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.