Hello,

On Thu, Apr 12, 2018 at 06:56:26PM +0000, Bart Van Assche wrote:
> On Thu, 2018-04-12 at 11:11 -0700, t...@kernel.org wrote:
> > * Right now, blk_queue_enter/exit() doesn't have any annotations.
> >   IOW, there's no way for paths which need enter locked to actually
> >   assert that.  If we're gonna protect more things with queue
> >   enter/exit, it gotta be annotated.
> 
> Hello Tejun,
> 
> One possibility is to check the count for the local CPU of q->q_usage_counter
> at runtime, e.g. using WARN_ON_ONCE(). However, that might have a runtime
> overhead. Another possibility is to follow the example of kernfs and to use
> a lockdep map and lockdep_assert_held(). There might be other alternatives I
> have not thought of.

Oh, I'd just do straight-forward lockdep annotation on
queue_enter/exit functions and provide the necessary assert helpers.

Thanks.

-- 
tejun

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