dma_fence_array_enable_signaling() runs while holding the array
inline_lock and may add callbacks to underlying fences, which takes
their inline_lock.
Since both locks share the same lockdep class, this valid nesting
triggers a recursive locking warning. Assign a distinct lockdep class
to the array inline_lock so lockdep can correctly model the hierarchy.
Fixes: 5943243914b9 ("dma-buf: use inline lock for the dma-fence-array")
Cc: Christian König <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Philipp Stanner <[email protected]>
Cc: Boris Brezillon <[email protected]>
Signed-off-by: Matthew Brost <[email protected]>
---
v2:
- Drop if IS_ENABLED(CONFIG_LOCKDEP), lockdep does this
---
drivers/dma-buf/dma-fence-array.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/dma-buf/dma-fence-array.c
b/drivers/dma-buf/dma-fence-array.c
index cd970eceaefb..089f69469524 100644
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -200,6 +200,8 @@ void dma_fence_array_init(struct dma_fence_array *array,
u64 context, unsigned seqno,
bool signal_on_any)
{
+ static struct lock_class_key dma_fence_array_lock_key;
+
WARN_ON(!num_fences || !fences);
array->num_fences = num_fences;
@@ -208,6 +210,18 @@ void dma_fence_array_init(struct dma_fence_array *array,
seqno);
init_irq_work(&array->work, irq_dma_fence_array_work);
+ /*
+ * dma_fence_array_enable_signaling() is invoked while holding
+ * array->base.inline_lock and may call dma_fence_add_callback()
+ * on the underlying fences, which takes their inline_lock.
+ *
+ * Since both locks share the same lockdep class, this legitimate
+ * nesting confuses lockdep and triggers a recursive locking
+ * warning. Assign a separate lockdep class to the array lock
+ * to model this hierarchy correctly.
+ */
+ lockdep_set_class(&array->base.inline_lock, &dma_fence_array_lock_key);
+
atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
array->fences = fences;
--
2.34.1
