From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: [PATCH 1/5] drm/i915: don't trylock in the gpu reset code Date: Wed, 4 Jul 2012 22:18:39 +0200 Message-ID: <1341433123-23055-2-git-send-email-daniel.vetter@ffwll.ch> References: <1341433123-23055-1-git-send-email-daniel.vetter@ffwll.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-we0-f177.google.com (mail-we0-f177.google.com [74.125.82.177]) by gabe.freedesktop.org (Postfix) with ESMTP id AE92B9E989 for ; Wed, 4 Jul 2012 13:18:53 -0700 (PDT) Received: by werb13 with SMTP id b13so2863517wer.36 for ; Wed, 04 Jul 2012 13:18:52 -0700 (PDT) In-Reply-To: <1341433123-23055-1-git-send-email-daniel.vetter@ffwll.ch> 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: Intel Graphics Development Cc: Daniel Vetter List-Id: intel-gfx@lists.freedesktop.org Simply failing to reset the gpu because someone else might still hold the mutex isn't a great idea - I see reliable silent reset failures. And gpu reset simply needs to be reliable and Just Work. "But ... the deadlocks!" We already kick all processes waiting for the gpu before launching the reset work item. New waiters need to check the wedging state anyway and then bail out. If we have places that can deadlock, we simply need to fix them. "But ... testing!" We have the gpu hangman, and if the current gpu load gem_exec_nop isn't good enough to hit a specific case, we can add a new one. "But ... don't we return -EAGAIN for non-interruptible calls to wait_seqno now?" Yep, but this problem already exists in the current code. A follow up patch will remedy this by returning -EIO for non-interruptible sleeps if the gpu died and the low-level wait bails out with -EAGAIN. Signed-Off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_drv.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 6edb2d5..e754cdf 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -730,8 +730,7 @@ int i915_reset(struct drm_device *dev) if (!i915_try_reset) return 0; - if (!mutex_trylock(&dev->struct_mutex)) - return -EBUSY; + mutex_lock(&dev->struct_mutex); i915_gem_reset(dev); -- 1.7.10