From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, torvalds@linux-foundation.org,
tglx@linutronix.de, ilya.dryomov@inktank.com,
umgwanakikbuti@gmail.com, linux-kernel@vger.kernel.org,
Eric Paris <eparis@parisplace.org>,
John McCutchan <john@johnmccutchan.com>,
Robert Love <rlove@rlove.org>
Subject: Re: [RFC][PATCH 4/7] inotify: Deal with nested sleeps
Date: Mon, 4 Aug 2014 21:23:58 +0200 [thread overview]
Message-ID: <20140804192358.GA23283@redhat.com> (raw)
In-Reply-To: <20140804103537.564978189@infradead.org>
On 08/04, Peter Zijlstra wrote:
>
> while (1) {
> - prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
> -
> mutex_lock(&group->notification_mutex);
So yes, even these 2 lines look obviously buggy. Even if
fsnotify_add_notify_event()->wake_up(&group->notification_waitq) uses
TASK_NORMAL, so at least this can't miss an event.
It is too later for me, but I am wondering if we can do another thing.
Something like
int state;
prepare_to_wait(wait, TASK_INTERRUPTIBLE);
PUSH(&wait, state);
mutex_lock();
mutex_unlock();
POP(&wait, state);
and, ignoring all races, lack of barriers, etc
#define PUSH(w, s) s = current->state; current->state = RUNNING;
#define POP(w, s) current->state = WOKEN(w) ? RUNNING : s;
Probably not... just curious.
Oleg.
next prev parent reply other threads:[~2014-08-04 19:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-04 10:30 [RFC][PATCH 0/7] nested sleeps, fixes and debug infra Peter Zijlstra
2014-08-04 10:30 ` [RFC][PATCH 1/7] wait: Provide infrastructure to deal with nested blocking Peter Zijlstra
2014-08-04 13:44 ` Peter Zijlstra
2014-08-04 18:35 ` Oleg Nesterov
2014-08-04 10:30 ` [RFC][PATCH 2/7] wait: Provide Peter Zijlstra
2014-08-04 10:30 ` [RFC][PATCH 3/7] exit: Desl with nested sleeps Peter Zijlstra
2014-08-04 18:53 ` Oleg Nesterov
2014-08-04 10:30 ` [RFC][PATCH 4/7] inotify: Deal " Peter Zijlstra
2014-08-04 19:23 ` Oleg Nesterov [this message]
2014-08-04 21:02 ` Peter Zijlstra
2014-08-05 2:22 ` Lai Jiangshan
2014-08-05 7:28 ` Peter Zijlstra
2014-08-04 10:30 ` [RFC][PATCH 5/7] tty: " Peter Zijlstra
2014-08-05 23:29 ` Greg Kroah-Hartman
2014-08-04 10:30 ` [RFC][PATCH 6/7] smp: Correctly deal " Peter Zijlstra
2014-08-04 10:30 ` [RFC][PATCH 7/7] sched: Debug " Peter Zijlstra
2014-08-05 8:33 ` [RFC][PATCH 0/7] nested sleeps, fixes and debug infra Ilya Dryomov
2014-08-05 13:06 ` Peter Zijlstra
2014-08-06 7:51 ` Ilya Dryomov
2014-08-06 8:31 ` Peter Zijlstra
2014-08-06 21:16 ` David Miller
2014-08-07 8:10 ` Peter Zijlstra
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