locking/atomic, kref: Add kref_read()

Since we need to change the implementation, stop exposing internals.

Provide kref_read() to read the current reference count; typically
used for debug messages.

Kills two anti-patterns:

	atomic_read(&kref->refcount)
	kref->refcount.counter

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

5 files changed, 11 insertions, 6 deletions

diff --git a/include/drm/drm_framebuffer.h b/include/drm/drm_framebuffer.h
index 1ddfa2928802..a232e7f0c869 100644
--- a/include/drm/drm_framebuffer.h
+++ b/include/drm/drm_framebuffer.h
@@ -247,7 +247,7 @@ static inline void drm_framebuffer_unreference(struct drm_framebuffer *fb)
  */
 static inline uint32_t drm_framebuffer_read_refcount(struct drm_framebuffer *fb)
 {
-	return atomic_read(&fb->base.refcount.refcount);
+	return kref_read(&fb->base.refcount);
 }
 
 /**
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index cdbdb40eb5bd..feecf33a1212 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -878,7 +878,7 @@ static inline int ttm_bo_reserve(struct ttm_buffer_object *bo,
 {
 	int ret;
 
-	WARN_ON(!atomic_read(&bo->kref.refcount));
+	WARN_ON(!kref_read(&bo->kref));
 
 	ret = __ttm_bo_reserve(bo, interruptible, no_wait, ticket);
 	if (likely(ret == 0))
@@ -903,7 +903,7 @@ static inline int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
 {
 	int ret = 0;
 
-	WARN_ON(!atomic_read(&bo->kref.refcount));
+	WARN_ON(!kref_read(&bo->kref));
 
 	if (interruptible)
 		ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
diff --git a/include/linux/kref.h b/include/linux/kref.h
index 9af255ad1e2f..7c88d865f82f 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -35,6 +35,11 @@ static inline void kref_init(struct kref *kref)
 	atomic_set(&kref->refcount, 1);
 }
 
+static inline int kref_read(const struct kref *kref)
+{
+	return atomic_read(&kref->refcount);
+}
+
 /**
  * kref_get - increment refcount for object.
  * @kref: object.
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index 62a60eeacb0a..8a511c0985aa 100644
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -198,7 +198,7 @@ static inline struct cache_head  *cache_get(struct cache_head *h)
 
 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 {
-	if (atomic_read(&h->ref.refcount) <= 2 &&
+	if (kref_read(&h->ref) <= 2 &&
 	    h->expiry_time < cd->nextcheck)
 		cd->nextcheck = h->expiry_time;
 	kref_put(&h->ref, cd->cache_put);
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 554671c81f4a..90708f68cc02 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -987,7 +987,7 @@ static inline void hci_conn_drop(struct hci_conn *conn)
 static inline void hci_dev_put(struct hci_dev *d)
 {
 	BT_DBG("%s orig refcnt %d", d->name,
-	       atomic_read(&d->dev.kobj.kref.refcount));
+	       kref_read(&d->dev.kobj.kref));
 
 	put_device(&d->dev);
 }
@@ -995,7 +995,7 @@ static inline void hci_dev_put(struct hci_dev *d)
 static inline struct hci_dev *hci_dev_hold(struct hci_dev *d)
 {
 	BT_DBG("%s orig refcnt %d", d->name,
-	       atomic_read(&d->dev.kobj.kref.refcount));
+	       kref_read(&d->dev.kobj.kref));
 
 	get_device(&d->dev);
 	return d;