On 26/11/2019 06:55, Chris Wilson wrote:
On context retiring, we may invoke the kernel_context to unpin this
context. Elsewhere, we may use the kernel_context to modify this
context. This currently leads to an AB-BA lock inversion, so we need to
back-off from the contended lock, and repeat.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111732
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_context.c | 6 ++----
1 file changed, 2 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..4fcb98f96da6 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -310,10 +310,8 @@ 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;
+ 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);
Please just drop a short comment above the trylock since with git blame
it is often very hard to find the commit.
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Regards,
Tvrtko
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