From: Jarek Poplawski <jarkao2@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fbcon: fix lockdep warning from fbcon_deinit()
Date: Mon, 13 Sep 2010 22:35:40 +0000 [thread overview]
Message-ID: <20100913223540.GB2176@del.dom.local> (raw)
In-Reply-To: <20100913152127.c2328034.akpm@linux-foundation.org>
On Mon, Sep 13, 2010 at 03:21:27PM -0700, Andrew Morton wrote:
> On Mon, 13 Sep 2010 23:58:50 +0200
> Jarek Poplawski <jarkao2@gmail.com> wrote:
>
> > This patch fixes the lockdep warning:
> >
> > [ 13.657164] INFO: trying to register non-static key.
> > [ 13.657169] the code is fine but needs lockdep annotation.
> > [ 13.657171] turning off the locking correctness validator.
> > [ 13.657177] Pid: 622, comm: modprobe Not tainted 2.6.36-rc3c #8
> > [ 13.657180] Call Trace:
> > [ 13.657194] [<c13002c8>] ? printk+0x18/0x20
> > [ 13.657202] [<c1056cf6>] register_lock_class+0x336/0x350
> > [ 13.657208] [<c1058bf9>] __lock_acquire+0x449/0x1180
> > [ 13.657215] [<c1059997>] lock_acquire+0x67/0x80
> > [ 13.657222] [<c1042bf1>] ? __cancel_work_timer+0x51/0x230
> > [ 13.657227] [<c1042c23>] __cancel_work_timer+0x83/0x230
> > [ 13.657231] [<c1042bf1>] ? __cancel_work_timer+0x51/0x230
> > [ 13.657236] [<c10582b2>] ? mark_held_locks+0x62/0x80
> > [ 13.657243] [<c10b3a2f>] ? kfree+0x7f/0xe0
> > [ 13.657248] [<c105853c>] ? trace_hardirqs_on_caller+0x11c/0x160
> > [ 13.657253] [<c105858b>] ? trace_hardirqs_on+0xb/0x10
> > [ 13.657259] [<c117f4cd>] ? fbcon_deinit+0x16d/0x1e0
> > [ 13.657263] [<c117f4cd>] ? fbcon_deinit+0x16d/0x1e0
> > [ 13.657268] [<c1042dea>] cancel_work_sync+0xa/0x10
> > [ 13.657272] [<c117f444>] fbcon_deinit+0xe4/0x1e0
> > ...
> >
> > The warning is caused by trying to cancel an uninitialized work from
> > fbcon_exit(). Fix it by adding a check for queue.func, similarly to
> > other places in this code.
> >
> > Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
> > ---
> >
> > diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
> > index 84f8423..7ccc967 100644
> > --- a/drivers/video/console/fbcon.c
> > +++ b/drivers/video/console/fbcon.c
> > @@ -3508,7 +3508,7 @@ static void fbcon_exit(void)
> > softback_buf = 0UL;
> >
> > for (i = 0; i < FB_MAX; i++) {
> > - int pending;
> > + int pending = 0;
> >
> > mapped = 0;
> > info = registered_fb[i];
> > @@ -3516,7 +3516,8 @@ static void fbcon_exit(void)
> > if (info = NULL)
> > continue;
> >
> > - pending = cancel_work_sync(&info->queue);
> > + if (info->queue.func)
> > + pending = cancel_work_sync(&info->queue);
> > DPRINTK("fbcon: %s pending work\n", (pending ? "canceled" :
> > "no"));
> >
>
> Well. It'd be better to just initialise the dang thing.
>
> But all that code looks really hacky, fiddling around inside workqueue
> internals as a driver-private state variable. Needs a rewrite, I suspect.
>
Sure, it's a fast hack. Proper fix, or at least verifying if there
could more such uninitialized things, is welcome.
Jarek P.
next prev parent reply other threads:[~2010-09-13 22:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-13 21:58 [PATCH] fbcon: fix lockdep warning from fbcon_deinit() Jarek Poplawski
2010-09-13 22:21 ` Andrew Morton
2010-09-13 22:35 ` Jarek Poplawski [this message]
2010-09-15 19:01 ` James Simmons
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