Commit 92ec0767 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm/msm: Don't init ww_mutec acquire ctx before needed



For locking semantics it really doesn't matter when we grab the
ticket. But for lockdep validation it does: the acquire ctx is a fake
lockdep. Since other drivers might want to do a full multi-lock dance
in their fault-handler, not just lock a single dma_resv. Therefore we
must init the acquire_ctx only after we've done all the copy_*_user or
anything else that might trigger a pagefault. For msm this means we
need to move it past submit_lookup_objects.

Aside: Why is msm still using struct_mutex, it seems to be using
dma_resv_lock for general buffer state protection?

v2:
- Add comment to explain why the ww ticket setup is separate (Rob)
- Fix up error handling, we need to make sure we don't call
  ww_acquire_fini without _init.

Reviewed-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-and-tested-by: default avatarRob Clark <robdclark@gmail.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Link: https://patchwork.freedesktop.org/patch/msgid/20191120105607.3023-1-daniel.vetter@ffwll.ch
parent fedf7a44
Loading
Loading
Loading
Loading
+6 −3
Original line number Diff line number Diff line
@@ -54,7 +54,6 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,

	INIT_LIST_HEAD(&submit->node);
	INIT_LIST_HEAD(&submit->bo_list);
	ww_acquire_init(&submit->ticket, &reservation_ww_class);

	return submit;
}
@@ -390,8 +389,6 @@ static void submit_cleanup(struct msm_gem_submit *submit)
		list_del_init(&msm_obj->submit_entry);
		drm_gem_object_put(&msm_obj->base);
	}

	ww_acquire_fini(&submit->ticket);
}

int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
@@ -408,6 +405,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
	struct msm_ringbuffer *ring;
	int out_fence_fd = -1;
	struct pid *pid = get_pid(task_pid(current));
	bool has_ww_ticket = false;
	unsigned i;
	int ret, submitid;
	if (!gpu)
@@ -489,6 +487,9 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
	if (ret)
		goto out;

	/* copy_*_user while holding a ww ticket upsets lockdep */
	ww_acquire_init(&submit->ticket, &reservation_ww_class);
	has_ww_ticket = true;
	ret = submit_lock_objects(submit);
	if (ret)
		goto out;
@@ -588,6 +589,8 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,

out:
	submit_cleanup(submit);
	if (has_ww_ticket)
		ww_acquire_fini(&submit->ticket);
	if (ret)
		msm_gem_submit_free(submit);
out_unlock: