From: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>,
Steve French <sfrench-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
"J. Bruce Fields"
<bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>,
Neil Brown <neilb-l3A5Bk7waGM@public.gmane.org>,
trond.myklebust-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org,
linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake TASK_KILLABLE tasks too"
Date: Tue, 1 Nov 2011 18:59:53 +0100 [thread overview]
Message-ID: <20111101175953.GB5358@redhat.com> (raw)
In-Reply-To: <20111101163059.GR18855-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
On 11/01, Tejun Heo wrote:
>
> diddling with
> sigmask in kernel generally isn't a good idea.
Agreed.
> If there are only a handful sites which need this type of behavior,
> wouldn't something like the following work?
>
> #define wait_event_freezekillable(wq, condition) \
> do { \
> DEFINE_WAIT(__wait); \
> for (;;) { \
> prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
> if (condition || fatal_signal_pending(current)) \
> break; \
> schedule(); \
No, this can't work, afaics.
Once the caller recieves a non-fatal signal (gets TIF_SIGPENDING),
schedule() won't block in TASK_INTERRUPTIBLE state.
IOW, wait_event_freezekillable() becomes a busy-wait loop.
Oleg.
WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Jeff Layton <jlayton@redhat.com>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
Steve French <sfrench@samba.org>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
linux-cifs@vger.kernel.org,
"J. Bruce Fields" <bfields@fieldses.org>,
Neil Brown <neilb@suse.de>,
trond.myklebust@netapp.com, linux-nfs@vger.kernel.org
Subject: Re: [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake TASK_KILLABLE tasks too"
Date: Tue, 1 Nov 2011 18:59:53 +0100 [thread overview]
Message-ID: <20111101175953.GB5358@redhat.com> (raw)
In-Reply-To: <20111101163059.GR18855@google.com>
On 11/01, Tejun Heo wrote:
>
> diddling with
> sigmask in kernel generally isn't a good idea.
Agreed.
> If there are only a handful sites which need this type of behavior,
> wouldn't something like the following work?
>
> #define wait_event_freezekillable(wq, condition) \
> do { \
> DEFINE_WAIT(__wait); \
> for (;;) { \
> prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
> if (condition || fatal_signal_pending(current)) \
> break; \
> schedule(); \
No, this can't work, afaics.
Once the caller recieves a non-fatal signal (gets TIF_SIGPENDING),
schedule() won't block in TASK_INTERRUPTIBLE state.
IOW, wait_event_freezekillable() becomes a busy-wait loop.
Oleg.
next prev parent reply other threads:[~2011-11-01 17:59 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-31 22:17 [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake TASK_KILLABLE tasks too" Tejun Heo
2011-10-31 22:17 ` Tejun Heo
[not found] ` <20111031221743.GA18855-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-10-31 23:17 ` Tejun Heo
2011-10-31 23:17 ` Tejun Heo
2011-10-31 23:24 ` Rafael J. Wysocki
2011-10-31 23:24 ` Rafael J. Wysocki
2011-10-31 23:30 ` Tejun Heo
2011-11-01 0:55 ` Tejun Heo
[not found] ` <20111101005505.GO18855-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-11-01 8:13 ` Jeff Layton
2011-11-01 8:13 ` Jeff Layton
[not found] ` <20111101041337.39077229-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2011-11-01 10:59 ` Jeff Layton
2011-11-01 10:59 ` Jeff Layton
[not found] ` <20111101065958.50addab5-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2011-11-01 16:30 ` Tejun Heo
2011-11-01 16:30 ` Tejun Heo
[not found] ` <20111101163059.GR18855-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-11-01 16:49 ` Trond Myklebust
2011-11-01 16:49 ` Trond Myklebust
[not found] ` <1320166171.5019.1.camel-SyLVLa/KEI9HwK5hSS5vWB2eb7JE58TQ@public.gmane.org>
2011-11-01 16:55 ` Tejun Heo
2011-11-01 16:55 ` Tejun Heo
2011-11-01 17:59 ` Oleg Nesterov [this message]
2011-11-01 17:59 ` Oleg Nesterov
[not found] ` <20111101175953.GB5358-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2011-11-01 18:06 ` Tejun Heo
2011-11-01 18:06 ` Tejun Heo
[not found] ` <20111101180601.GV18855-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-11-01 18:13 ` Oleg Nesterov
2011-11-01 18:13 ` Oleg Nesterov
[not found] ` <20111101181329.GA6739-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2011-11-01 18:27 ` Tejun Heo
2011-11-01 18:27 ` Tejun Heo
[not found] ` <20111101182753.GW18855-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-11-01 19:39 ` Oleg Nesterov
2011-11-01 19:39 ` Oleg Nesterov
[not found] ` <20111101193923.GA9444-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2011-11-01 19:46 ` Oleg Nesterov
2011-11-01 19:46 ` Oleg Nesterov
2011-11-01 21:57 ` Tejun Heo
[not found] ` <20111101215710.GA13803-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-11-02 11:42 ` Jeff Layton
2011-11-02 11:42 ` Jeff Layton
[not found] ` <20111102074257.7174691c-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2011-11-02 15:13 ` Oleg Nesterov
2011-11-02 15:13 ` Oleg Nesterov
2011-11-02 16:23 ` Oleg Nesterov
2011-11-02 16:23 ` Oleg Nesterov
[not found] ` <20111102162331.GA31947-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2011-11-02 23:11 ` Rafael J. Wysocki
2011-11-02 23:11 ` Rafael J. Wysocki
2011-11-03 11:15 ` Jeff Layton
[not found] ` <201111030011.24062.rjw-KKrjLPT3xs0@public.gmane.org>
2011-11-03 15:10 ` Oleg Nesterov
2011-11-03 15:10 ` Oleg Nesterov
2011-11-02 17:53 ` [PATCH] wait_event_freezekillable: use freezer_do_not_count/freezer_count Oleg Nesterov
2011-11-02 17:53 ` Oleg Nesterov
2011-11-03 10:42 ` Jeff Layton
[not found] ` <20111103064215.48939e1a-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2011-11-03 14:13 ` Tejun Heo
2011-11-03 14:13 ` Tejun Heo
[not found] ` <20111103141354.GB4417-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-11-03 15:27 ` Jeff Layton
2011-11-03 15:27 ` Jeff Layton
[not found] ` <20111103112704.4b905bfc-xSBYVWDuneFaJnirhKH9O4GKTjYczspe@public.gmane.org>
2011-11-03 15:30 ` Tejun Heo
2011-11-03 15:30 ` Tejun Heo
2011-11-01 18:26 ` [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake TASK_KILLABLE tasks too" Jeff Layton
2011-11-01 18:26 ` Jeff Layton
[not found] ` <201111010024.16659.rjw-KKrjLPT3xs0@public.gmane.org>
2011-10-31 23:45 ` Steve French
2011-10-31 23:45 ` Steve French
[not found] ` <CAH2r5msMiG8MjhYuVv8ehqkBLKc1Av3hi+2q6zwrrXdTTa_+YQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-10-31 23:53 ` Tejun Heo
2011-10-31 23:53 ` Tejun Heo
[not found] ` <20111031235335.GL18855-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-11-01 0:02 ` Steve French
2011-11-01 0:02 ` Steve French
2011-11-01 17:50 ` Oleg Nesterov
2011-11-01 17:50 ` Oleg Nesterov
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