Localise the static struct lock_class_key to the caller of
i915_sw_fence_init() so that we create a lock_class instance for each
unique sw_fence rather than all sw_fences sharing the same
lock_class. This eliminate some lockdep false positive when using fences
from within fence callbacks.
For the relatively small number of fences currently in use [2], this adds
160 bytes of unused text/code when lockdep is disabled. This seems
quite high, but fully reducing it via ifdeffery is also quite ugly.
Removing the #fence strings saves 72 bytes with just a single #ifdef.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_sw_fence.c | 7 +++++--
drivers/gpu/drm/i915/i915_sw_fence.h | 17 ++++++++++++++++-
2 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 95f2f12e0917..147420ccf49c 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -116,11 +116,14 @@ static void i915_sw_fence_await(struct i915_sw_fence *fence)
WARN_ON(atomic_inc_return(&fence->pending) <= 1);
}
-void i915_sw_fence_init(struct i915_sw_fence *fence, i915_sw_fence_notify_t fn)
+void __i915_sw_fence_init(struct i915_sw_fence *fence,
+ i915_sw_fence_notify_t fn,
+ const char *name,
+ struct lock_class_key *key)
{
BUG_ON((unsigned long)fn & ~I915_SW_FENCE_MASK);
- init_waitqueue_head(&fence->wait);
+ __init_waitqueue_head(&fence->wait, name, key);
kref_init(&fence->kref);
atomic_set(&fence->pending, 1);
fence->flags = (unsigned long)fn;
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h b/drivers/gpu/drm/i915/i915_sw_fence.h
index 707dfc4f0da5..7508d23f823b 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.h
+++ b/drivers/gpu/drm/i915/i915_sw_fence.h
@@ -40,7 +40,22 @@ typedef int (*i915_sw_fence_notify_t)(struct i915_sw_fence *,
enum i915_sw_fence_notify state);
#define __i915_sw_fence_call __aligned(4)
-void i915_sw_fence_init(struct i915_sw_fence *fence, i915_sw_fence_notify_t fn);
+void __i915_sw_fence_init(struct i915_sw_fence *fence,
+ i915_sw_fence_notify_t fn,
+ const char *name,
+ struct lock_class_key *key);
+#ifdef CONFIG_LOCKDEP
+#define i915_sw_fence_init(fence, fn) \
+do { \
+ static struct lock_class_key __key; \
+ \
+ __i915_sw_fence_init((fence), (fn), #fence, &__key); \
+} while (0)
+#else
+#define i915_sw_fence_init(fence, fn) \
+ __i915_sw_fence_init((fence), (fn), NULL, NULL)
+#endif
+
void i915_sw_fence_commit(struct i915_sw_fence *fence);
int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
--
2.10.2
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