From de2b998552c1534e87bfbc51ec5734b02bc89020 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 4 Jul 2012 22:52:50 +0200 Subject: [PATCH] drm/i915: don't return a spurious -EIO from intel_ring_begin The issue with this check is that it results in userspace receiving an -EIO while the gpu reset hasn't completed, resulting in fallback to sw rendering or worse. Now there's also a stern comment in intel_ring_wait_seqno saying that intel_ring_begin should not return -EAGAIN, ever, because some callers can't handle that. But after an audit of the callsites I don't see any issues. I guess the last problematic spot disappeared with the removal of the pipelined fencing code. So do the right thing and call check_wedge, which should properly decide whether an -EAGAIN or -EIO is appropriate if wedged is set. Note that the early check for a wedged gpu before touching the ring is rather important (and it took me quite some time of acting like the densest doofus to figure that out): If we don't do that and the gpu died for good, not having been resurrect by the reset code, userspace can merrily fill up the entire ring until it notices that something is amiss. Allowing userspace to emit more render, despite that we know that it will fail can't lead to anything good (and by experience can lead to all sorts of havoc, including angering the OOM gods and hard-hanging the hw for good). v2: Fix EAGAIN mispell, noticed by Chris Wilson. Reviewed-by: Chris Wilson Tested-by: Chris Wilson Signed-Off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_ringbuffer.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index cd35ad4922de..d42d821c64d6 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -1117,20 +1117,9 @@ static int intel_wrap_ring_buffer(struct intel_ring_buffer *ring) static int intel_ring_wait_seqno(struct intel_ring_buffer *ring, u32 seqno) { - struct drm_i915_private *dev_priv = ring->dev->dev_private; - bool was_interruptible; int ret; - /* XXX As we have not yet audited all the paths to check that - * they are ready for ERESTARTSYS from intel_ring_begin, do not - * allow us to be interruptible by a signal. - */ - was_interruptible = dev_priv->mm.interruptible; - dev_priv->mm.interruptible = false; - ret = i915_wait_seqno(ring, seqno); - - dev_priv->mm.interruptible = was_interruptible; if (!ret) i915_gem_retire_requests_ring(ring); @@ -1240,12 +1229,13 @@ int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n) int intel_ring_begin(struct intel_ring_buffer *ring, int num_dwords) { - struct drm_i915_private *dev_priv = ring->dev->dev_private; + drm_i915_private_t *dev_priv = ring->dev->dev_private; int n = 4*num_dwords; int ret; - if (unlikely(atomic_read(&dev_priv->mm.wedged))) - return -EIO; + ret = i915_gem_check_wedge(dev_priv, dev_priv->mm.interruptible); + if (ret) + return ret; if (unlikely(ring->tail + n > ring->effective_size)) { ret = intel_wrap_ring_buffer(ring);