diff options
| -rw-r--r-- | drivers/gpu/drm/i915/gt/intel_context.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c index ee9d2bcd2c13..ef7bc41ffffa 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.c +++ b/drivers/gpu/drm/i915/gt/intel_context.c @@ -310,10 +310,23 @@ int intel_context_prepare_remote_request(struct intel_context *ce, GEM_BUG_ON(rq->hw_context == ce); if (rcu_access_pointer(rq->timeline) != tl) { /* timeline sharing! */ - err = mutex_lock_interruptible_nested(&tl->mutex, - SINGLE_DEPTH_NESTING); - if (err) - return err; + /* + * Ideally, we just want to insert our foreign fence as + * a barrier into the remove context, such that this operation + * occurs after all current operations in that context, and + * all future operations must occur after this. + * + * Currently, the timeline->last_request tracking is guarded + * by its mutex and so we must obtain that to atomically + * insert our barrier. However, since we already hold our + * timeline->mutex, we must be careful against potential + * inversion if we are the kernel_context as the remote context + * will itself poke at the kernel_context when it needs to + * unpin. Ergo, if already locked, we drop both locks and + * try again (through the magic of userspace repeating EAGAIN). + */ + if (!mutex_trylock(&tl->mutex)) + return -EAGAIN; /* Queue this switch after current activity by this context. */ err = i915_active_fence_set(&tl->last_request, rq); |