Similar to for i915_active.mutex, we require each class of i915_active
to have distinct lockdep chains as some, but by no means all,
i915_active are used within the shrinker and so have much more severe
usage constraints. By using a lockclass local to i915_active_init() all
i915_active workers have the same lock class, and we may generate false
positives when waiting for the i915_active. If we push the lockclass
into the caller, each class of i915_active will have distinct lockdep
chains.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_active.c | 8 ++++++--
drivers/gpu/drm/i915/i915_active.h | 10 +++++++---
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index 479195ecbc6c..e60e44986c9d 100644
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -277,7 +277,8 @@ active_instance(struct i915_active *ref, struct intel_timeline *tl)
void __i915_active_init(struct i915_active *ref,
int (*active)(struct i915_active *ref),
void (*retire)(struct i915_active *ref),
- struct lock_class_key *key)
+ struct lock_class_key *mkey,
+ struct lock_class_key *wkey)
{
unsigned long bits;
@@ -295,9 +296,12 @@ void __i915_active_init(struct i915_active *ref,
init_llist_head(&ref->preallocated_barriers);
atomic_set(&ref->count, 0);
- __mutex_init(&ref->mutex, "i915_active", key);
+ __mutex_init(&ref->mutex, "i915_active", mkey);
__i915_active_fence_init(&ref->excl, NULL, excl_retire);
INIT_WORK(&ref->work, active_work);
+#if IS_ENABLED(CONFIG_LOCKDEP)
+ lockdep_init_map(&ref->work.lockdep_map, "i915_active.work", wkey, 0);
+#endif
}
static bool ____active_del_barrier(struct i915_active *ref,
diff --git a/drivers/gpu/drm/i915/i915_active.h b/drivers/gpu/drm/i915/i915_active.h
index 3208cc2e8c1a..b571f675c795 100644
--- a/drivers/gpu/drm/i915/i915_active.h
+++ b/drivers/gpu/drm/i915/i915_active.h
@@ -152,11 +152,15 @@ i915_active_fence_isset(const struct i915_active_fence *active)
void __i915_active_init(struct i915_active *ref,
int (*active)(struct i915_active *ref),
void (*retire)(struct i915_active *ref),
- struct lock_class_key *key);
+ struct lock_class_key *mkey,
+ struct lock_class_key *wkey);
+
+/* Specialise each class of i915_active to avoid impossible lockdep cycles. */
#define i915_active_init(ref, active, retire) do { \
- static struct lock_class_key __key; \
+ static struct lock_class_key __mkey; \
+ static struct lock_class_key __wkey; \
\
- __i915_active_init(ref, active, retire, &__key); \
+ __i915_active_init(ref, active, retire, &__mkey, &__wkey); \
} while (0)
int i915_active_ref(struct i915_active *ref,
--
2.24.0
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