[PATCH 3/3] drm/msm: Don't init ww_mutec acquire ctx before needed

[Daniel Vetter]

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?

Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Cc: Rob Clark <robdclark at gmail.com>
Cc: Sean Paul <sean at poorly.run>
Cc: linux-arm-msm at vger.kernel.org
Cc: freedreno at lists.freedesktop.org
---
 drivers/gpu/drm/msm/msm_gem_submit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index fb1fdd7fa3ef..126b2f62bfe7 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -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;
 }
@@ -489,6 +488,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	if (ret)
 		goto out;
 
+	ww_acquire_init(&submit->ticket, &reservation_ww_class);
 	ret = submit_lock_objects(submit);
 	if (ret)
 		goto out;
-- 
2.24.0