drm/i915: Reduce locking inside swfinish ioctl (c21724cc) · Commits · 戴 / test

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) v3: READ_ONCE, obj->pin_display is not a bitfield anymore v4: Don't be creative with goto. Signed-off-by:

Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by:

Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-14-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem.c

+12 −15

Original line number	Diff line number	Diff line
		@@ -1518,26 +1518,23 @@ 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 err = 0;

		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 (READ_ONCE(obj->pin_display)) {
		err = i915_mutex_lock_interruptible(dev);
		if (!err) {
		i915_gem_object_flush_cpu_write_domain(obj);

		i915_gem_object_put(obj);
		unlock:
		mutex_unlock(&dev->struct_mutex);
		return ret;
		}
		}

		i915_gem_object_put_unlocked(obj);
		return err;
		}

		/**

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