From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH 1/5] drm/i915: downgrade non-lethal BUG_ONs Date: Wed, 20 Apr 2011 15:36:13 +0100 Message-ID: <1bdc18$k9v09n@fmsmga002.fm.intel.com> References: <1303245964-3022-1-git-send-email-daniel.vetter@ffwll.ch> <1303245964-3022-2-git-send-email-daniel.vetter@ffwll.ch> <20110420142724.GA12270@lundgren.kumite> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by gabe.freedesktop.org (Postfix) with ESMTP id 4D6D19E971 for ; Wed, 20 Apr 2011 07:36:33 -0700 (PDT) In-Reply-To: <20110420142724.GA12270@lundgren.kumite> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Ben Widawsky Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Wed, 20 Apr 2011 07:27:24 -0700, Ben Widawsky wrote: > On Wed, Apr 20, 2011 at 09:18:03AM +0100, Chris Wilson wrote: > > > > diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c > > > index 316603e..8cac87c 100644 > > > --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c > > > +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c > > > @@ -1093,7 +1093,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data, > > > &objects, eb, > > > exec, > > > args->buffer_count); > > > - BUG_ON(!mutex_is_locked(&dev->struct_mutex)); > > > + WARN_ON(!mutex_is_locked(&dev->struct_mutex)); > > > > I think this can be dropped after close inspection of the call path. > > > > Is that right? There are definitely cases where the mutex is released > and not reacquired. You would know better than I if those cases can > occur in a normal system. Assuming they can, Won't we just BUG_ON when > we try to release struct_mutex? This particular BUG_ON() I added at Daniel's request to clarify the reservation fallback logic. Code inspection should be sufficient to verify that the BUG_ON() is not required, and by now we should be happy that we didn't miss anything. -Chris -- Chris Wilson, Intel Open Source Technology Centre