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* [Intel-xe] [PATCH v5 1/7] drm: fix drmm_mutex_init()
@ 2023-05-17 15:22 Matthew Auld
  2023-05-17 15:22 ` [Intel-xe] [PATCH v5 2/7] Revert "drm/xe: Use atomic instead of mutex for xe_device_mem_access_ongoing" Matthew Auld
                   ` (18 more replies)
  0 siblings, 19 replies; 31+ messages in thread
From: Matthew Auld @ 2023-05-17 15:22 UTC (permalink / raw)
  To: intel-xe; +Cc: Jocelyn Falempe, dri-devel, Thomas Zimmermann, Daniel Vetter

In mutex_init() lockdep seems to identify a lock by defining a static
key for each lock class. However if we wrap the whole thing in a
function the static key will be the same for everything calling that
function, which looks to be the case for drmm_mutex_init(). This then
results in impossible lockdep splats since lockdep thinks completely
unrelated locks are the same lock class. The other issue is that when
looking at splats we lose the actual lock name, where instead of seeing
something like xe->mem_access.lock for the name, we just see something
generic like lock#8.

Attempt to fix this by converting drmm_mutex_init() into a macro, which
should ensure that mutex_init() behaves as expected.

Reported-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Fixes: e13f13e039dc ("drm: Add DRM-managed mutex_init()")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
---
 drivers/gpu/drm/drm_managed.c | 26 --------------------------
 include/drm/drm_managed.h     | 23 ++++++++++++++++++++++-
 2 files changed, 22 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c
index 4cf214de50c4..71c49819a7a2 100644
--- a/drivers/gpu/drm/drm_managed.c
+++ b/drivers/gpu/drm/drm_managed.c
@@ -263,29 +263,3 @@ void drmm_kfree(struct drm_device *dev, void *data)
 	free_dr(dr_match);
 }
 EXPORT_SYMBOL(drmm_kfree);
-
-static void drmm_mutex_release(struct drm_device *dev, void *res)
-{
-	struct mutex *lock = res;
-
-	mutex_destroy(lock);
-}
-
-/**
- * drmm_mutex_init - &drm_device-managed mutex_init()
- * @dev: DRM device
- * @lock: lock to be initialized
- *
- * Returns:
- * 0 on success, or a negative errno code otherwise.
- *
- * This is a &drm_device-managed version of mutex_init(). The initialized
- * lock is automatically destroyed on the final drm_dev_put().
- */
-int drmm_mutex_init(struct drm_device *dev, struct mutex *lock)
-{
-	mutex_init(lock);
-
-	return drmm_add_action_or_reset(dev, drmm_mutex_release, lock);
-}
-EXPORT_SYMBOL(drmm_mutex_init);
diff --git a/include/drm/drm_managed.h b/include/drm/drm_managed.h
index 359883942612..01f977e91933 100644
--- a/include/drm/drm_managed.h
+++ b/include/drm/drm_managed.h
@@ -105,6 +105,27 @@ char *drmm_kstrdup(struct drm_device *dev, const char *s, gfp_t gfp);
 
 void drmm_kfree(struct drm_device *dev, void *data);
 
-int drmm_mutex_init(struct drm_device *dev, struct mutex *lock);
+static inline void __drmm_mutex_release(struct drm_device *dev, void *res)
+{
+	struct mutex *lock = res;
+
+	mutex_destroy(lock);
+}
+
+/**
+ * drmm_mutex_init - &drm_device-managed mutex_init()
+ * @dev: DRM device
+ * @lock: lock to be initialized
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ *
+ * This is a &drm_device-managed version of mutex_init(). The initialized
+ * lock is automatically destroyed on the final drm_dev_put().
+ */
+#define drmm_mutex_init(dev, lock) ({					     \
+	mutex_init(lock);						     \
+	drmm_add_action_or_reset(dev, __drmm_mutex_release, lock);	     \
+})									     \
 
 #endif
-- 
2.40.1


^ permalink raw reply related	[flat|nested] 31+ messages in thread

end of thread, other threads:[~2023-05-22  9:49 UTC | newest]

Thread overview: 31+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-05-17 15:22 [Intel-xe] [PATCH v5 1/7] drm: fix drmm_mutex_init() Matthew Auld
2023-05-17 15:22 ` [Intel-xe] [PATCH v5 2/7] Revert "drm/xe: Use atomic instead of mutex for xe_device_mem_access_ongoing" Matthew Auld
2023-05-17 15:22 ` [Intel-xe] [PATCH v5 3/7] drm/xe: don't allocate under ct->lock Matthew Auld
2023-05-17 15:50   ` Rodrigo Vivi
2023-05-17 15:22 ` [Intel-xe] [PATCH v5 4/7] drm/xe: keep pulling mem_access_get further back Matthew Auld
2023-05-17 15:53   ` Rodrigo Vivi
2023-05-17 15:22 ` [Intel-xe] [PATCH v5 5/7] drm/xe/ggtt: prime ggtt->lock against FS_RECLAIM Matthew Auld
2023-05-17 15:48   ` Rodrigo Vivi
2023-05-17 16:21     ` Matthew Auld
2023-05-17 15:22 ` [Intel-xe] [PATCH v5 6/7] drm/xe: fix xe_device_mem_access_get() races Matthew Auld
2023-05-19 20:25   ` Rodrigo Vivi
2023-05-22  9:49     ` Matthew Auld
2023-05-17 15:22 ` [Intel-xe] [PATCH v5 7/7] drm/xe: Use atomic for mem_access.ref Matthew Auld
2023-05-17 15:25 ` [Intel-xe] ✓ CI.Patch_applied: success for series starting with [v5,1/7] drm: fix drmm_mutex_init() Patchwork
2023-05-17 15:27 ` [Intel-xe] ✓ CI.KUnit: " Patchwork
2023-05-17 15:31 ` [Intel-xe] ✓ CI.Build: " Patchwork
2023-05-17 15:49 ` [Intel-xe] ○ CI.BAT: info " Patchwork
2023-05-17 16:05 ` [Intel-xe] [PATCH v5 1/7] " Stanislaw Gruszka
2023-05-17 16:29   ` Matthew Auld
2023-05-17 17:03     ` Thomas Hellström
2023-05-17 17:47       ` Thomas Zimmermann
2023-05-17 16:21 ` Thomas Zimmermann
2023-05-17 17:04   ` Matthew Auld
2023-05-17 17:43     ` Thomas Zimmermann
2023-05-18  9:51 ` [Intel-xe] ✓ CI.Patch_applied: success for series starting with [v5,1/7] drm: fix drmm_mutex_init() (rev2) Patchwork
2023-05-18  9:52 ` [Intel-xe] ✓ CI.KUnit: " Patchwork
2023-05-18  9:56 ` [Intel-xe] ✓ CI.Build: " Patchwork
2023-05-18 10:16 ` [Intel-xe] ○ CI.BAT: info " Patchwork
2023-05-19 15:49 ` [Intel-xe] ✓ CI.Patch_applied: success for series starting with [v5,1/7] drm: fix drmm_mutex_init() (rev3) Patchwork
2023-05-19 15:50 ` [Intel-xe] ✓ CI.KUnit: " Patchwork
2023-05-19 15:54 ` [Intel-xe] ✓ CI.Build: " Patchwork

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