On 25/07/2019 14:14, Chris Wilson wrote:
Modifying a remote context requires careful serialisation with requests
on that context, and that serialisation requires us to take their
timeline->mutex. Make it so.
Note that while struct_mutex rules, we can't create more than one
request in parallel, but that age is soon coming to an end.
v2: Though it doesn't affect the current users, contexts may share
timelines so check if we already hold the right mutex.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_context.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 9292b6ca5e9c..d64b45f7ec6d 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -254,10 +254,18 @@ int intel_context_prepare_remote_request(struct intel_context *ce,
/* Only suitable for use in remotely modifying this context */
GEM_BUG_ON(rq->hw_context == ce);
- /* Queue this switch after all other activity by this context. */
- err = i915_active_request_set(&tl->last_request, rq);
- if (err)
- return err;
+ if (rq->timeline != tl) { /* beware timeline sharing */
+ err = mutex_lock_interruptible_nested(&tl->mutex,
+ SINGLE_DEPTH_NESTING);
+ if (err)
+ return err;
+
+ /* Queue this switch after current activity by this context. */
+ err = i915_active_request_set(&tl->last_request, rq);
+ if (err)
+ goto unlock;
+ }
+ lockdep_assert_held(&tl->mutex);
/*
* Guarantee context image and the timeline remains pinned until the
@@ -267,7 +275,12 @@ int intel_context_prepare_remote_request(struct intel_context *ce,
* words transfer the pinned ce object to tracked active request.
*/
GEM_BUG_ON(i915_active_is_idle(&ce->active));
- return i915_active_ref(&ce->active, rq->fence.context, rq);
+ err = i915_active_ref(&ce->active, rq->fence.context, rq);
+
+unlock:
+ if (rq->timeline != tl)
+ mutex_unlock(&tl->mutex);
+ return err;
}
struct i915_request *intel_context_create_request(struct intel_context *ce)
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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