Commit 74ceefd1 authored by Daniel Vetter's avatar Daniel Vetter Committed by Maarten Lankhorst
Browse files

drm/i915: use might_lock_nested in get_pages annotation 



So strictly speaking the existing annotation is also ok, because we
have a chain of

obj->mm.lock#I915_MM_GET_PAGES -> fs_reclaim -> obj->mm.lock

(the shrinker cannot get at an object while we're in get_pages, hence
this is safe). But it's confusing, so try to take the right subclass
of the lock.

This does a bit reduce our lockdep based checking, but then it's also
less fragile, in case we ever change the nesting around.

Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191104173720.2696-3-daniel.vetter@ffwll.ch
parent e692b402

drivers/gpu/drm/i915/gem/i915_gem_object.h

+18 −18
Original line number Original line Diff line number Diff line
@@ -271,10 +271,27 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj, 
int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj);

int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj);

int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj);

int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj);





enum i915_mm_subclass { /* lockdep subclass for obj->mm.lock/struct_mutex */

	I915_MM_NORMAL = 0,

	/*

	 * Only used by struct_mutex, when called "recursively" from

	 * direct-reclaim-esque. Safe because there is only every one

	 * struct_mutex in the entire system.

	 */

	I915_MM_SHRINKER = 1,

	/*

	 * Used for obj->mm.lock when allocating pages. Safe because the object

	 * isn't yet on any LRU, and therefore the shrinker can't deadlock on

	 * it. As soon as the object has pages, obj->mm.lock nests within

	 * fs_reclaim.

	 */

	I915_MM_GET_PAGES = 1,

};



static inline int __must_check

static inline int __must_check

i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)

i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)

{

{

	might_lock(&obj->mm.lock);

	might_lock_nested(&obj->mm.lock, I915_MM_GET_PAGES);





	if (atomic_inc_not_zero(&obj->mm.pages_pin_count))

	if (atomic_inc_not_zero(&obj->mm.pages_pin_count))

		return 0;

		return 0;
@@ -317,23 +334,6 @@ i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj) 
	__i915_gem_object_unpin_pages(obj);

	__i915_gem_object_unpin_pages(obj);

}

}





enum i915_mm_subclass { /* lockdep subclass for obj->mm.lock/struct_mutex */

	I915_MM_NORMAL = 0,

	/*

	 * Only used by struct_mutex, when called "recursively" from

	 * direct-reclaim-esque. Safe because there is only every one

	 * struct_mutex in the entire system.

	 */

	I915_MM_SHRINKER = 1,

	/*

	 * Used for obj->mm.lock when allocating pages. Safe because the object

	 * isn't yet on any LRU, and therefore the shrinker can't deadlock on

	 * it. As soon as the object has pages, obj->mm.lock nests within

	 * fs_reclaim.

	 */

	I915_MM_GET_PAGES = 1,

};



int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj);

int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj);

void i915_gem_object_truncate(struct drm_i915_gem_object *obj);

void i915_gem_object_truncate(struct drm_i915_gem_object *obj);

void i915_gem_object_writeback(struct drm_i915_gem_object *obj);

void i915_gem_object_writeback(struct drm_i915_gem_object *obj);

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