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drm/i915: Give each sw_fence its own lockclass

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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@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114204105.29171-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2016-11-14 20:40:56 +00:00
parent e3c566dfe4
commit 556b748710
2 changed files with 21 additions and 3 deletions
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7
drivers/gpu/drm/i915/i915_sw_fence.c
View File

@ -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;

17
drivers/gpu/drm/i915/i915_sw_fence.h
View File

@ -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,