[PATCH 1/6][SRU][OEM-5.17] drm: Add DRM-managed mutex_init()

[AceLan Kao]

From: Thomas Zimmermann <tzimmermann at suse.de>

BugLink: https://launchpad.net/bugs/1995573

Add drmm_mutex_init(), a helper that provides managed mutex cleanup. The
mutex will be destroyed with the final reference of the DRM device.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe at redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220502142514.2174-2-tzimmermann@suse.de
(cherry picked from commit e13f13e039dc8f31168b5569120a7658035c80ee)
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
---
 drivers/gpu/drm/drm_managed.c | 27 +++++++++++++++++++++++++++
 include/drm/drm_managed.h     |  3 +++
 2 files changed, 30 insertions(+)

diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c
index 37d7db6223be..4cf214de50c4 100644
--- a/drivers/gpu/drm/drm_managed.c
+++ b/drivers/gpu/drm/drm_managed.c
@@ -8,6 +8,7 @@
 #include <drm/drm_managed.h>
 
 #include <linux/list.h>
+#include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 
@@ -262,3 +263,29 @@ 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 b45c6fbf53ac..359883942612 100644
--- a/include/drm/drm_managed.h
+++ b/include/drm/drm_managed.h
@@ -8,6 +8,7 @@
 #include <linux/types.h>
 
 struct drm_device;
+struct mutex;
 
 typedef void (*drmres_release_t)(struct drm_device *dev, void *res);
 
@@ -104,4 +105,6 @@ 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);
+
 #endif
-- 
2.34.1