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: 25+ 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 8:33 ` Ilya Dryomov
2014-08-05 13:06 ` Peter Zijlstra
2014-08-06 7:51 ` Ilya Dryomov
2014-08-06 7:51 ` Ilya Dryomov
2014-08-06 8:31 ` Peter Zijlstra
2014-08-06 21:16 ` David Miller
2014-08-06 21:16 ` David Miller
2014-08-07 8:10 ` Peter Zijlstra
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=20140804192358.GA23283@redhat.com \
--to=oleg@redhat.com \
--cc=eparis@parisplace.org \
--cc=ilya.dryomov@inktank.com \
--cc=john@johnmccutchan.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=rlove@rlove.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=umgwanakikbuti@gmail.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.