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From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
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> (raw)
In-Reply-To: <1341433123-23055-1-git-send-email-daniel.vetter@ffwll.ch>

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 <daniel.vetter@ffwll.ch>
---
 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

  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-04 20:18 [PATCH 0/5] reset rework, 2nd try Daniel Vetter
2012-07-04 20:18 ` Daniel Vetter [this message]
2012-07-04 20:18 ` [PATCH 2/5] drm/i915: non-interruptible sleeps can't handle -EGAIN Daniel Vetter
2012-07-04 20:54   ` [PATCH] drm/i915: non-interruptible sleeps can't handle -EAGAIN Daniel Vetter
2012-07-04 20:18 ` [PATCH 3/5] drm/i915: don't hang userspace when the gpu reset is stuck Daniel Vetter
2012-07-04 20:18 ` [PATCH 4/5] drm/i915: properly SIGBUS on I/O errors Daniel Vetter
2012-07-04 20:40   ` Daniel Vetter
2012-07-04 20:18 ` [PATCH 5/5] drm/i915: don't return a spurious -EIO from intel_ring_begin Daniel Vetter
2012-07-04 20:52   ` [PATCH] " Daniel Vetter
2012-07-04 20:54 ` [PATCH 0/5] reset rework, 2nd try Chris Wilson
2012-07-05  8:04   ` Daniel Vetter

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