[PATCH] drm: Do not use BUG_ON(!spin_is_locked())

sanjeev sharma sanjeevsharmaengg at gmail.com
Mon Aug 11 22:44:30 PDT 2014

Thanks all and I replaced with lockdep_assert_held() which seems less

Sanjeev Sharma

On Tue, Aug 12, 2014 at 5:08 AM, David Rientjes <rientjes at google.com> wrote:

> On Mon, 11 Aug 2014, Rob Clark wrote:
> > > I'm suggesting that if you don't want to incur the cost of the
> conditional
> > > everytime you call a certain function with assert_spin_locked() that
> you
> > > could covert these to lockdep_assert_held() so the check is only done
> when
> > > lockdep is enabled for debugging.
> >
> > not sure about the nouveau parts, but for the omap and msm hunks, this
> > code getting called at potentially vblank rate (so maybe once or twice
> > per ~16ms)..  and lockdep has considerable overhead (for a gpu driver)
> > so I don't always have it enabled.  So it sounds like for those two at
> > least assert_spin_locked() is a better option.
> >
> Unless there's a bug, assert_spin_locked() is just going to incur an
> unnecessary cost every time it is called at runtime.  My suggestion was to
> limit that check only to debugging kernels that include enabling lockdep
> when tracking down problems rather than needlessly evaluating the
> conditional every time when there are no bugs.
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