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Subject: Lots of bugs with current->state = TASK_*INTERRUPTIBLE
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: LKML <linux-kernel@vger.kernel.org>
Cc: 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>
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Organization: Kihon Technologies Inc.
Date: Tue, 19 Jan 2010 15:29:38 -0500
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Peter Zijlstra and I were doing a look over of places that assign
current->state = TASK_*INTERRUPTIBLE, by simply looking at places with:

 $ git grep -A1 'state[[:space:]]*=[[:space:]]*TASK_[^R]'

and it seems there are quite a few places that looks like bugs. To be on
the safe side, everything outside of a run queue lock that sets the
current state to something other than TASK_RUNNING (or dead) should be
using set_current_state().

	current->state = TASK_INTERRUPTIBLE;
	schedule();

is probably OK, but it would not hurt to be consistent. Here's a few
examples of likely bugs:

>From drivers/staging/line6/midi.c:

        current->state = TASK_INTERRUPTIBLE;

        while (line6->line6midi->num_active_send_urbs > 0)

>From drivers/staging/line6/pod.c:

        current->state = TASK_INTERRUPTIBLE;

        while (param->value == POD_system_invalid) {


Also drivers/macintosh/adb.c looks like there's a bug too.

I'm sure there's others but I stopped looking.

Anyway, this looks like a good janitorial work. Anything that assigns
state outside the rq locks to something other than TASK_RUNNING and that
is not before a schedule() (perhaps even those) should be converted to:

	set_current_task(<state>).

This probably should be checked in checkpatch.pl too, if it is not
already.

-- Steve


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