Hello, Greg.

On Mon, Dec 10, 2012 at 12:35:39PM -0800, Greg KH wrote:
> On Thu, Dec 06, 2012 at 01:34:28PM -0700, Shuah Khan wrote:
> > Changed BUG_ON()s in queue_delayed_work() to WARN_ON_ONCE()s so that
> > incorrect use of delayed_work() triggers warnings, but doesn't crash
> > the system. This change is back-ported from upstream change that converted
> > BUG_ON()s in __queue_delayed_work() to WARN_ON_ONCE()s.
> > 
> > Upstream commit: fc4b514f2727f74a4587c31db87e0e93465518c3
> > Tested on Stable Trees: 3.0.x, 3.4.x, 3.6.x
> > 
> > Signed-off-by: Tejun Heo <[email protected]>
> > Cc: Xiaotian Feng <[email protected]>
> > Signed-off-by: Shuah Khan <[email protected]>
> > CC: [email protected]
> > ---
> >  kernel/workqueue.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> > index 872bd6d..3262ea9 100644
> > --- a/kernel/workqueue.c
> > +++ b/kernel/workqueue.c
> > @@ -1143,8 +1143,8 @@ int queue_delayed_work_on(int cpu, struct 
> > workqueue_struct *wq,
> >     if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
> >             unsigned int lcpu;
> >  
> > -           BUG_ON(timer_pending(timer));
> > -           BUG_ON(!list_empty(&work->entry));
> > +           WARN_ON_ONCE(timer_pending(timer));
> > +           WARN_ON_ONCE(!list_empty(&work->entry));
> >  
> >             timer_stats_timer_set_start_info(&dwork->timer);
> >  
> 
> Shuah, is this something that is user triggerable for the stable kernel
> releases?

No, it isn't.  The only known case for which this makes any difference
is megaraid_sas after mod_delayed_work() changes, so it's strictly
necessary only for >= 3.7.  I think Linus tagged it stable just in
case.

> Tejun, any objections for me taking this in the older kernel releases?

It's not gonna hurt anything and I generally think it's a good idea to
have WARN_ON_ONCE() instead of BUG_ON() there, so no objections from
me.

Thanks.

-- 
tejun
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