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| author | Ben Widawsky <ben@bwidawsk.net> | 2011-12-12 19:21:57 -0800 |
|---|---|---|
| committer | Keith Packard <keithp@keithp.com> | 2012-01-03 09:09:44 -0800 |
| commit | e2971bdab2b761683353da383c0fd5ac704d1cca (patch) | |
| tree | e85a6591108ae7a5aa0cf0bb2bb6a1bc85b1ae5e /drivers | |
| parent | 7a7e8734ac3235efafd34819b27fbdf5417e6d60 (diff) | |
| download | linux-e2971bdab2b761683353da383c0fd5ac704d1cca.tar.gz linux-e2971bdab2b761683353da383c0fd5ac704d1cca.tar.bz2 linux-e2971bdab2b761683353da383c0fd5ac704d1cca.zip | |
drm/i915: relative_constants_mode race fix
dev_priv keeps track of the current addressing mode that gets set at
execbuffer time. Unfortunately the existing code was doing this before
acquiring struct_mutex which leaves a race with another thread also
doing an execbuffer. If that wasn't bad enough, relocate_slow drops
struct_mutex which opens a much more likely error where another thread
comes in and modifies the state while relocate_slow is being slow.
The solution here is to just defer setting this state until we
absolutely need it, and we know we'll have struct_mutex for the
remainder of our code path.
v2: Keith noticed a bug in the original patch.
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Keith Packard <keithp@keithp.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem_execbuffer.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index c681dc149d2a..68e5b41dc7f2 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -1033,19 +1033,6 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data, if (INTEL_INFO(dev)->gen > 5 && mode == I915_EXEC_CONSTANTS_REL_SURFACE) return -EINVAL; - - ret = intel_ring_begin(ring, 4); - if (ret) - return ret; - - intel_ring_emit(ring, MI_NOOP); - intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1)); - intel_ring_emit(ring, INSTPM); - intel_ring_emit(ring, - I915_EXEC_CONSTANTS_MASK << 16 | mode); - intel_ring_advance(ring); - - dev_priv->relative_constants_mode = mode; } break; default: @@ -1176,6 +1163,22 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data, } } + if (ring == &dev_priv->ring[RCS] && + mode != dev_priv->relative_constants_mode) { + ret = intel_ring_begin(ring, 4); + if (ret) + goto err; + + intel_ring_emit(ring, MI_NOOP); + intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1)); + intel_ring_emit(ring, INSTPM); + intel_ring_emit(ring, + I915_EXEC_CONSTANTS_MASK << 16 | mode); + intel_ring_advance(ring); + + dev_priv->relative_constants_mode = mode; + } + trace_i915_gem_ring_dispatch(ring, seqno); exec_start = batch_obj->gtt_offset + args->batch_start_offset; |