On Fri, Jun 03, 2016 at 05:55:42PM +0100, Chris Wilson wrote:
> We only need to take the struct_mutex if the object is pinned to the
> display engine and so requires checking for clflush. (The race with
> userspace pinning the object to a framebuffer is irrelevant.)
>
> v2: Use access once for compiler hints (or not as it is a bitfield)
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 29 ++++++++++++++++-------------
> 1 file changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a4f949038d50..b78f9df1894c 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1265,25 +1265,28 @@ i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
> {
> struct drm_i915_gem_sw_finish *args = data;
> struct drm_i915_gem_object *obj;
> - int ret = 0;
> -
> - ret = i915_mutex_lock_interruptible(dev);
> - if (ret)
> - return ret;
> + int ret;
>
> obj = i915_gem_object_lookup(file, args->handle);
> - if (!obj) {
> - ret = -ENOENT;
> - goto unlock;
> - }
> + if (!obj)
> + return -ENOENT;
>
> /* Pinned buffers may be scanout, so flush the cache */
> - if (obj->pin_display)
> + if (obj->pin_display) {
READ_ONCE(obj->pin_display)?
> + ret = i915_mutex_lock_interruptible(dev);
> + if (ret)
> + goto unref;
> +
> i915_gem_object_flush_cpu_write_domain(obj);
>
> - i915_gem_object_put(obj);
> -unlock:
> - mutex_unlock(&dev->struct_mutex);
> + i915_gem_object_put(obj);
> + mutex_unlock(&dev->struct_mutex);
> + } else {
> + ret = 0;
> +unref:
> + i915_gem_object_put_unlocked(obj);
> + }
> +
> return ret;
> }
>
> --
> 2.8.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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