From 9f0ba539d13aebacb05dda542df7ef80684b2c70 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 2 May 2016 10:40:51 +0200 Subject: drm/gem: support BO freeing without dev->struct_mutex Finally all the core gem and a lot of drivers are entirely free of dev->struct_mutex depencies, and we can start to have an entirely lockless unref path. To make sure that no one who touches the core code accidentally breaks existing drivers which still require dev->struct_mutex I've made the might_lock check unconditional. While at it de-inline the ref/unref functions, they've become a bit too big. v2: Make it not leak like a sieve. v3: Review from Lucas: - drop != NULL in pointer checks. - fixup copypasted kerneldoc to actually match the functions. v4: Add __drm_gem_object_unreference as a fastpath helper for drivers who abolished dev->struct_mutex, requested by Chris. v5: Fix silly mistake in drm_gem_object_unreference_unlocked caught by intel-gfx CI - I checked for gem_free_object instead of gem_free_object_unlocked ... Cc: Chris Wilson Cc: Alex Deucher Cc: Lucas Stach Reviewed-by: Lucas Stach (v3) Reviewed-by: Chris Wilson (v4) Reviewed-by: Alex Deucher Signed-off-by: Daniel Vetter Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1462178451-1765-1-git-send-email-daniel.vetter@ffwll.ch --- drivers/gpu/drm/drm_gem.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/drm_gem.c') diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 25dac31..973eb88 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -806,12 +806,64 @@ drm_gem_object_free(struct kref *kref) WARN_ON(!mutex_is_locked(&dev->struct_mutex)); - if (dev->driver->gem_free_object != NULL) + if (dev->driver->gem_free_object_unlocked) + dev->driver->gem_free_object_unlocked(obj); + else if (dev->driver->gem_free_object) dev->driver->gem_free_object(obj); } EXPORT_SYMBOL(drm_gem_object_free); /** + * drm_gem_object_unreference_unlocked - release a GEM BO reference + * @obj: GEM buffer object + * + * This releases a reference to @obj. Callers must not hold the + * dev->struct_mutex lock when calling this function. + * + * See also __drm_gem_object_unreference(). + */ +void +drm_gem_object_unreference_unlocked(struct drm_gem_object *obj) +{ + struct drm_device *dev; + + if (!obj) + return; + + dev = obj->dev; + might_lock(&dev->struct_mutex); + + if (dev->driver->gem_free_object_unlocked) + kref_put(&obj->refcount, drm_gem_object_free); + else if (kref_put_mutex(&obj->refcount, drm_gem_object_free, + &dev->struct_mutex)) + mutex_unlock(&dev->struct_mutex); +} +EXPORT_SYMBOL(drm_gem_object_unreference_unlocked); + +/** + * drm_gem_object_unreference - release a GEM BO reference + * @obj: GEM buffer object + * + * This releases a reference to @obj. Callers must hold the dev->struct_mutex + * lock when calling this function, even when the driver doesn't use + * dev->struct_mutex for anything. + * + * For drivers not encumbered with legacy locking use + * drm_gem_object_unreference_unlocked() instead. + */ +void +drm_gem_object_unreference(struct drm_gem_object *obj) +{ + if (obj) { + WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex)); + + kref_put(&obj->refcount, drm_gem_object_free); + } +} +EXPORT_SYMBOL(drm_gem_object_unreference); + +/** * drm_gem_vm_open - vma->ops->open implementation for GEM * @vma: VM area structure * -- cgit v1.1