Re: [PATCH UPDATED 10/13] block, cfq: unlink cfq_io_context'simmediately

From: Tejun Heo
Date: Thu Oct 27 2011 - 12:17:11 EST


Hello,

On Thu, Oct 27, 2011 at 10:31:19AM -0400, Vivek Goyal wrote:
> On Wed, Oct 26, 2011 at 02:31:07PM -0700, Tejun Heo wrote:
> > BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
> > + if (locked_q)
> > + lockdep_assert_held(locked_q->queue_lock);
> >
>
> Looks like lockdep_assert_held() can't be used if !CONFIG_LOCKDEP. So
> Jens had put following patch to fix one compilation issue. You might
> want to provide a null definition of lockdep_assert_held() in case
> of !CONFIG_LOCKDEP.
>
> commit 334c2b0b8b2ab186fa198413386cba41fffcb4f2
> Author: Jens Axboe <axboe@xxxxxxxxx>
> Date: Tue Oct 25 15:51:48 2011 +0200
>
> blk-throttle: use queue_is_locked() instead of lockdep_is_held()
>
> We can't use the latter if !CONFIG_LOCKDEP.
>
> Reported-by: Sedat Dilek <sedat.dilek@xxxxxxxxxxxxxx>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>

Eh? lockdep.h has dummy definition if !CONFIG_LOCKDEP. If
lockdep_is_held() is causing compilation failure on !CONFIG_LOCKDEP,
it's more likely to be have been caused by missing include than
anything else. Jens, what was the failure? lockdep_is_held()
provides way better protection against locking mistakes than
spin_is_locked().

Thanks.

--
tejun
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