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drm/i915: Skip taking acquire mutex for no ref->active callback 

If no active callback is defined for i915_active, we do not need to
serialise its enabling with the mutex. We still do only want to call the
debug activate once, and must still serialise with a concurrent retire.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200731085015.32368-2-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
This commit is contained in:
Chris Wilson 2020-07-31 09:50:10 +01:00 committed by Joonas Lahtinen
parent bde246d893
commit 04240e30ed
1 changed files with 16 additions and 8 deletions
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24
drivers/gpu/drm/i915/i915_active.c
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@ -416,6 +416,14 @@ bool i915_active_acquire_if_busy(struct i915_active *ref)
return atomic_add_unless(&ref->count, 1, 0);
}
static void __i915_active_activate(struct i915_active *ref)
{
spin_lock_irq(&ref->tree_lock); /* __active_retire() */
if (!atomic_fetch_inc(&ref->count))
debug_active_activate(ref);
spin_unlock_irq(&ref->tree_lock);
}
int i915_active_acquire(struct i915_active *ref)
{
int err;
@ -423,19 +431,19 @@ int i915_active_acquire(struct i915_active *ref)
if (i915_active_acquire_if_busy(ref))
return 0;
if (!ref->active) {
__i915_active_activate(ref);
return 0;
}
err = mutex_lock_interruptible(&ref->mutex);
if (err)
return err;
if (likely(!i915_active_acquire_if_busy(ref))) {
if (ref->active)
err = ref->active(ref);
if (!err) {
spin_lock_irq(&ref->tree_lock); /* __active_retire() */
debug_active_activate(ref);
atomic_inc(&ref->count);
spin_unlock_irq(&ref->tree_lock);
}
err = ref->active(ref);
if (!err)
__i915_active_activate(ref);
}
mutex_unlock(&ref->mutex);