[PATCH 10/10] dma-buf: Inline dma_resv_init and remove allocated flag

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Now that all users have migrated to dma_resv_alloc(), inline the
initialization code directly into dma_resv_alloc() and remove the
dma_resv_init() function entirely.

Additionally, remove the 'allocated' flag from struct dma_resv since
all dma_resv objects are now dynamically allocated. This simplifies
the reference counting logic - dma_resv_release() now always frees
the object unconditionally.

The last remaining use of dma_resv_init() in dma_resv_lockdep() has
been converted to use dma_resv_alloc() instead.

Signed-off-by: Christian König <christian.koenig@amd.com>
Assisted-by: Claude:Sonnet 4
---
 drivers/dma-buf/dma-resv.c | 41 ++++++++++++++++----------------------
 include/linux/dma-resv.h   | 10 ----------
 2 files changed, 17 insertions(+), 34 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 48798cec6ce7..a3586e79c2eb 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -132,26 +132,13 @@ static void dma_resv_list_free(struct dma_resv_list *list)
 	kfree_rcu(list, rcu);
 }
 
-/**
- * dma_resv_init - initialize a reservation object
- * @obj: the reservation object
- */
-void dma_resv_init(struct dma_resv *obj)
-{
-	kref_init(&obj->refcount);
-	obj->allocated = false;
-	ww_mutex_init(&obj->lock, &reservation_ww_class);
-
-	RCU_INIT_POINTER(obj->fences, NULL);
-}
-EXPORT_SYMBOL(dma_resv_init);
-
 /*
  * dma_resv_release - release function for kref
  * @kref: the kref inside the dma_resv object
  *
  * This is called when the last reference to a dma_resv object is released.
- * Cleans up the object and frees it if it was allocated by dma_resv_alloc().
+ * All dma_resv objects are now dynamically allocated, so this always frees
+ * the object after cleanup.
  */
 static void dma_resv_release(struct kref *kref)
 {
@@ -159,8 +146,7 @@ static void dma_resv_release(struct kref *kref)
 
 	dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
 	ww_mutex_destroy(&obj->lock);
-	if (obj->allocated)
-		kfree(obj);
+	kfree(obj);
 }
 
 /**
@@ -181,8 +167,9 @@ struct dma_resv *dma_resv_alloc(void)
 	if (!obj)
 		return NULL;
 
-	dma_resv_init(obj);
-	obj->allocated = true;
+	kref_init(&obj->refcount);
+	ww_mutex_init(&obj->lock, &reservation_ww_class);
+	RCU_INIT_POINTER(obj->fences, NULL);
 
 	return obj;
 }
@@ -838,23 +825,28 @@ static int __init dma_resv_lockdep(void)
 {
 	struct mm_struct *mm = mm_alloc();
 	struct ww_acquire_ctx ctx;
-	struct dma_resv obj;
+	struct dma_resv *obj;
 	struct address_space mapping;
 	int ret;
 
 	if (!mm)
 		return -ENOMEM;
 
-	dma_resv_init(&obj);
+	obj = dma_resv_alloc();
+	if (!obj) {
+		mmput(mm);
+		return -ENOMEM;
+	}
+
 	address_space_init_once(&mapping);
 
 	mmap_read_lock(mm);
 	ww_acquire_init(&ctx, &reservation_ww_class);
-	ret = dma_resv_lock(&obj, &ctx);
+	ret = dma_resv_lock(obj, &ctx);
 	if (ret) {
 		/* Only EDEADLK from the error injection is possible here */
 		WARN_ON(ret != -EDEADLK);
-		dma_resv_lock_slow(&obj, &ctx);
+		dma_resv_lock_slow(obj, &ctx);
 	}
 	fs_reclaim_acquire(GFP_KERNEL);
 	/* for unmap_mapping_range on trylocked buffer objects in shrinkers */
@@ -868,10 +860,11 @@ static int __init dma_resv_lockdep(void)
 	__dma_fence_might_wait();
 #endif
 	fs_reclaim_release(GFP_KERNEL);
-	ww_mutex_unlock(&obj.lock);
+	ww_mutex_unlock(&obj->lock);
 	ww_acquire_fini(&ctx);
 	mmap_read_unlock(mm);
 
+	dma_resv_put(obj);
 	mmput(mm);
 
 	return 0;
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 4d12519df34e..cf689d3d4ba6 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -162,15 +162,6 @@ struct dma_resv {
 	 */
 	struct kref refcount;
 
-	/**
-	 * @allocated:
-	 *
-	 * True if this object was allocated by dma_resv_alloc(), false if
-	 * embedded in another structure. Used to determine whether to free
-	 * the object memory in the release function.
-	 */
-	bool allocated;
-
 	/**
 	 * @lock:
 	 *
@@ -482,7 +473,6 @@ static inline void dma_resv_unlock(struct dma_resv *obj)
 	ww_mutex_unlock(&obj->lock);
 }
 
-void dma_resv_init(struct dma_resv *obj);
 struct dma_resv *dma_resv_alloc(void);
 struct dma_resv *dma_resv_get(struct dma_resv *obj);
 void dma_resv_put(struct dma_resv *obj);
-- 
2.43.0