From: Frederic Weisbecker <fweisbec@gmail.com>
To: Julia Lawall <julia@diku.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-janitors <kernel-janitors@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-arch@vger.kernel.org, Greg KH <greg@kroah.com>,
Andy Whitcroft <apw@canonical.com>
Subject: Re: Lots of bugs with current->state = TASK_*INTERRUPTIBLE
Date: Thu, 21 Jan 2010 10:53:14 +0000 [thread overview]
Message-ID: <20100121105311.GB5017@nowhere> (raw)
In-Reply-To: <Pine.LNX.4.64.1001211145480.13529@ask.diku.dk>
On Thu, Jan 21, 2010 at 11:47:41AM +0100, Julia Lawall wrote:
> What about something like the following (drivers/macintosh/adb.c):
>
> add_wait_queue(&state->wait_queue, &wait);
> current->state = TASK_INTERRUPTIBLE;
>
> for (;;) {
> req = state->completed;
> if (req != NULL)
> state->completed = req->next;
> else if (atomic_read(&state->n_pending) = 0)
> ret = -EIO;
> if (req != NULL || ret != 0)
> break;
>
> if (file->f_flags & O_NONBLOCK) {
> ret = -EAGAIN;
> break;
> }
> if (signal_pending(current)) {
> ret = -ERESTARTSYS;
> break;
> }
> spin_unlock_irqrestore(&state->lock, flags);
> schedule();
> spin_lock_irqsave(&state->lock, flags);
> }
>
> current->state = TASK_RUNNING;
> remove_wait_queue(&state->wait_queue, &wait);
>
> There is a call to schedule eventually after the first current->state
> assignment, but it is not right after.
Looks fine as spin_unlock includes a memory barrier, IIRC.
WARNING: multiple messages have this Message-ID (diff)
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Julia Lawall <julia@diku.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-janitors <kernel-janitors@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-arch@vger.kernel.org, Greg KH <greg@kroah.com>,
Andy Whitcroft <apw@canonical.com>
Subject: Re: Lots of bugs with current->state = TASK_*INTERRUPTIBLE
Date: Thu, 21 Jan 2010 11:53:14 +0100 [thread overview]
Message-ID: <20100121105311.GB5017@nowhere> (raw)
In-Reply-To: <Pine.LNX.4.64.1001211145480.13529@ask.diku.dk>
On Thu, Jan 21, 2010 at 11:47:41AM +0100, Julia Lawall wrote:
> What about something like the following (drivers/macintosh/adb.c):
>
> add_wait_queue(&state->wait_queue, &wait);
> current->state = TASK_INTERRUPTIBLE;
>
> for (;;) {
> req = state->completed;
> if (req != NULL)
> state->completed = req->next;
> else if (atomic_read(&state->n_pending) == 0)
> ret = -EIO;
> if (req != NULL || ret != 0)
> break;
>
> if (file->f_flags & O_NONBLOCK) {
> ret = -EAGAIN;
> break;
> }
> if (signal_pending(current)) {
> ret = -ERESTARTSYS;
> break;
> }
> spin_unlock_irqrestore(&state->lock, flags);
> schedule();
> spin_lock_irqsave(&state->lock, flags);
> }
>
> current->state = TASK_RUNNING;
> remove_wait_queue(&state->wait_queue, &wait);
>
> There is a call to schedule eventually after the first current->state
> assignment, but it is not right after.
Looks fine as spin_unlock includes a memory barrier, IIRC.
next prev parent reply other threads:[~2010-01-21 10:53 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-19 20:29 Lots of bugs with current->state = TASK_*INTERRUPTIBLE Steven Rostedt
2010-01-19 20:29 ` Steven Rostedt
2010-01-19 20:29 ` Steven Rostedt
2010-01-19 20:58 ` Julia Lawall
2010-01-19 20:58 ` Julia Lawall
2010-01-19 21:08 ` Steven Rostedt
2010-01-19 21:08 ` Steven Rostedt
2010-01-21 10:47 ` Julia Lawall
2010-01-21 10:47 ` Julia Lawall
2010-01-21 10:53 ` Frederic Weisbecker [this message]
2010-01-21 10:53 ` Frederic Weisbecker
2010-01-21 10:56 ` Peter Zijlstra
2010-01-21 10:56 ` Peter Zijlstra
2010-01-21 10:59 ` Frederic Weisbecker
2010-01-21 10:59 ` Frederic Weisbecker
2010-01-21 17:31 ` Steven Rostedt
2010-01-21 17:31 ` Steven Rostedt
2010-01-21 18:12 ` Julia Lawall
2010-01-21 18:12 ` Julia Lawall
2010-01-21 19:18 ` David Daney
2010-01-21 19:18 ` David Daney
2010-01-21 19:34 ` Steven Rostedt
2010-01-21 19:34 ` Steven Rostedt
2010-01-21 19:57 ` David Daney
2010-01-21 19:57 ` David Daney
2010-01-21 20:18 ` Steven Rostedt
2010-01-21 20:18 ` Steven Rostedt
2010-01-21 20:21 ` David Daney
2010-01-21 20:21 ` David Daney
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