[PATCH] workqueue: detect uninitated work_struct and BUG() if true

[PATCH] workqueue: detect uninitated work_struct and BUG() if true

[Du, Changbin]

>From cdebb88ac0fb3f900ef28f28ccb4a12159c295db Mon Sep 17 00:00:00 2001
From: "Du, Changbin" <changbin.du@gmail.com>
Date: Mon, 9 Mar 2015 12:06:43 +0800
Subject: [PATCH] workqueue: detect uninitated work_struct and BUG() if true

Recently I encounter a driver issue that caused by missing initializing
the work_struct. Then the work never get executed and stay in workqueue
forever. This take me some time to locate the error. This issue can be
seen early if detect it when queuing a work.

Signed-off-by: Du, Changbin <changbin.du@intel.com>
---
 kernel/workqueue.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f288493..5c1a5bc 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1295,6 +1295,9 @@ static void __queue_work(int cpu, struct workqueue_struct *wq,
 	 */
 	WARN_ON_ONCE(!irqs_disabled());
 
+	if (!work->func)
+		BUG();
+
 	debug_work_activate(work);
 
 	/* if draining, only works from the same workqueue are allowed */
-- 
1.9.1

Re: [PATCH] workqueue: detect uninitated work_struct and BUG() if true

[Tejun Heo]

On Mon, Mar 09, 2015 at 04:43:11AM +0000, Du, Changbin wrote:
> From cdebb88ac0fb3f900ef28f28ccb4a12159c295db Mon Sep 17 00:00:00 2001
> From: "Du, Changbin" <changbin.du@gmail.com>
> Date: Mon, 9 Mar 2015 12:06:43 +0800
> Subject: [PATCH] workqueue: detect uninitated work_struct and BUG() if true
> 
> Recently I encounter a driver issue that caused by missing initializing
> the work_struct. Then the work never get executed and stay in workqueue
> forever. This take me some time to locate the error. This issue can be
> seen early if detect it when queuing a work.
> 
> Signed-off-by: Du, Changbin <changbin.du@intel.com>
> ---
>  kernel/workqueue.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index f288493..5c1a5bc 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1295,6 +1295,9 @@ static void __queue_work(int cpu, struct workqueue_struct *wq,
>  	 */
>  	WARN_ON_ONCE(!irqs_disabled());
>  
> +	if (!work->func)
> +		BUG();
> +
>  	debug_work_activate(work);

Can't this be part of the debug_work mechanism?  I'm a bit wary of
adding essentially arbitrary checks.  I'd much prefer if it gets gated
by debug config somehow.

Thanks.

-- 
tejun

RE: [PATCH] workqueue: detect uninitated work_struct and BUG() if true

[Du, Changbin]

> -----Original Message-----
> From: Tejun Heo [mailto:htejun@gmail.com] On Behalf Of Tejun Heo
> Sent: Monday, March 9, 2015 2:23 PM
> To: Du, Changbin
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] workqueue: detect uninitated work_struct and BUG() if
> true
> > @@ -1295,6 +1295,9 @@ static void __queue_work(int cpu, struct
> workqueue_struct *wq,
> >  	 */
> >  	WARN_ON_ONCE(!irqs_disabled());
> >
> > +	if (!work->func)
> > +		BUG();
> > +
> >  	debug_work_activate(work);
> 
> Can't this be part of the debug_work mechanism?  I'm a bit wary of adding
> essentially arbitrary checks.  I'd much prefer if it gets gated by debug config
> somehow.
> 
> Thanks.
> Tejun

Yes, I found there already have this checking and print a warning in work_fixup_activate.
So this patch can be droped. Thanks for point out.

static int work_fixup_activate(void *addr, enum debug_obj_state state)
{
	struct work_struct *work = addr;

	switch (state) {

	case ODEBUG_STATE_NOTAVAILABLE:
		/*
		 * This is not really a fixup. The work struct was
		 * statically initialized. We just make sure that it
		 * is tracked in the object tracker.
		 */
		if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
			debug_object_init(work, &work_debug_descr);
			debug_object_activate(work, &work_debug_descr);
			return 0;
		}
		WARN_ON_ONCE(1);