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>

drivers/block/drbd/drbd_req.c

@@ -520,7 +520,7 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
 		/* Completion does it's own kref_put.  If we are going to
 		 * kref_sub below, we need req to be still around then. */
 		int at_least = k_put + !!c_put;
-		int refcount = atomic_read(&req->kref.refcount);
+		int refcount = kref_read(&req->kref);
 		if (refcount < at_least)
 			drbd_err(device,
 				"mod_rq_state: Logic BUG: %x -> %x: refcount = %d, should be >= %d\n",

drivers/block/rbd.c

@@ -1535,7 +1535,7 @@ static bool obj_request_overlaps_parent(struct rbd_obj_request *obj_request)
 static void rbd_obj_request_get(struct rbd_obj_request *obj_request)
 {
 	dout("%s: obj %p (was %d)\n", __func__, obj_request,
-		atomic_read(&obj_request->kref.refcount));
+		kref_read(&obj_request->kref));
 	kref_get(&obj_request->kref);
 }
 
@@ -1544,14 +1544,14 @@ static void rbd_obj_request_put(struct rbd_obj_request *obj_request)
 {
 	rbd_assert(obj_request != NULL);
 	dout("%s: obj %p (was %d)\n", __func__, obj_request,
-		atomic_read(&obj_request->kref.refcount));
+		kref_read(&obj_request->kref));
 	kref_put(&obj_request->kref, rbd_obj_request_destroy);
 }
 
 static void rbd_img_request_get(struct rbd_img_request *img_request)
 {
 	dout("%s: img %p (was %d)\n", __func__, img_request,
-	     atomic_read(&img_request->kref.refcount));
+	     kref_read(&img_request->kref));
 	kref_get(&img_request->kref);
 }
 
@@ -1562,7 +1562,7 @@ static void rbd_img_request_put(struct rbd_img_request *img_request)
 {
 	rbd_assert(img_request != NULL);
 	dout("%s: img %p (was %d)\n", __func__, img_request,
-		atomic_read(&img_request->kref.refcount));
+		kref_read(&img_request->kref));
 	if (img_request_child_test(img_request))
 		kref_put(&img_request->kref, rbd_parent_request_destroy);
 	else

drivers/block/virtio_blk.c

@@ -767,7 +767,7 @@ static void virtblk_remove(struct virtio_device *vdev)
 	/* Stop all the virtqueues. */
 	vdev->config->reset(vdev);
 
-	refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
+	refc = kref_read(&disk_to_dev(vblk->disk)->kobj.kref);
 	put_disk(vblk->disk);
 	vdev->config->del_vqs(vdev);
 	kfree(vblk->vqs);

drivers/gpu/drm/drm_gem_cma_helper.c

@@ -376,7 +376,7 @@ void drm_gem_cma_describe(struct drm_gem_cma_object *cma_obj,
 	off = drm_vma_node_start(&obj->vma_node);
 
 	seq_printf(m, "%2d (%2d) %08llx %pad %p %zu",
-			obj->name, obj->refcount.refcount.counter,
+			obj->name, kref_read(&obj->refcount),
 			off, &cma_obj->paddr, cma_obj->vaddr, obj->size);
 
 	seq_printf(m, "\n");

drivers/gpu/drm/drm_info.c

@@ -118,7 +118,7 @@ static int drm_gem_one_name_info(int id, void *ptr, void *data)
 	seq_printf(m, "%6d %8zd %7d %8d\n",
 		   obj->name, obj->size,
 		   obj->handle_count,
-		   atomic_read(&obj->refcount.refcount));
+		   kref_read(&obj->refcount));
 	return 0;
 }
 

drivers/gpu/drm/drm_mode_object.c

@@ -159,7 +159,7 @@ EXPORT_SYMBOL(drm_mode_object_find);
 void drm_mode_object_unreference(struct drm_mode_object *obj)
 {
 	if (obj->free_cb) {
-		DRM_DEBUG("OBJ ID: %d (%d)\n", obj->id, atomic_read(&obj->refcount.refcount));
+		DRM_DEBUG("OBJ ID: %d (%d)\n", obj->id, kref_read(&obj->refcount));
 		kref_put(&obj->refcount, obj->free_cb);
 	}
 }
@@ -176,7 +176,7 @@ EXPORT_SYMBOL(drm_mode_object_unreference);
 void drm_mode_object_reference(struct drm_mode_object *obj)
 {
 	if (obj->free_cb) {
-		DRM_DEBUG("OBJ ID: %d (%d)\n", obj->id, atomic_read(&obj->refcount.refcount));
+		DRM_DEBUG("OBJ ID: %d (%d)\n", obj->id, kref_read(&obj->refcount));
 		kref_get(&obj->refcount);
 	}
 }

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -486,7 +486,7 @@ static void etnaviv_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 
 	seq_printf(m, "%08x: %c %2d (%2d) %08lx %p %zd\n",
 			etnaviv_obj->flags, is_active(etnaviv_obj) ? 'A' : 'I',
-			obj->name, obj->refcount.refcount.counter,
+			obj->name, kref_read(&obj->refcount),
 			off, etnaviv_obj->vaddr, obj->size);
 
 	rcu_read_lock();

drivers/gpu/drm/i915/i915_gem_object.h

@@ -256,7 +256,7 @@ extern void drm_gem_object_unreference_unlocked(struct drm_gem_object *);
 static inline bool
 i915_gem_object_is_dead(const struct drm_i915_gem_object *obj)
 {
-	return atomic_read(&obj->base.refcount.refcount) == 0;
+	return kref_read(&obj->base.refcount) == 0;
 }
 
 static inline bool

drivers/gpu/drm/msm/msm_gem.c

@@ -640,7 +640,7 @@ void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 
 	seq_printf(m, "%08x: %c %2d (%2d) %08llx %p\t",
 			msm_obj->flags, is_active(msm_obj) ? 'A' : 'I',
-			obj->name, obj->refcount.refcount.counter,
+			obj->name, kref_read(&obj->refcount),
 			off, msm_obj->vaddr);
 
 	for (id = 0; id < priv->num_aspaces; id++)

drivers/gpu/drm/nouveau/nouveau_fence.c

@@ -527,7 +527,7 @@ static bool nouveau_fence_no_signaling(struct dma_fence *f)
 	 * caller should have a reference on the fence,
 	 * else fence could get freed here
 	 */
-	WARN_ON(atomic_read(&fence->base.refcount.refcount) <= 1);
+	WARN_ON(kref_read(&fence->base.refcount) <= 1);
 
 	/*
 	 * This needs uevents to work correctly, but dma_fence_add_callback relies on

drivers/gpu/drm/omapdrm/omap_gem.c

@@ -1033,7 +1033,7 @@ void omap_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 	off = drm_vma_node_start(&obj->vma_node);
 
 	seq_printf(m, "%08x: %2d (%2d) %08llx %pad (%2d) %p %4d",
-			omap_obj->flags, obj->name, obj->refcount.refcount.counter,
+			omap_obj->flags, obj->name, kref_read(&obj->refcount),
 			off, &omap_obj->paddr, omap_obj->paddr_cnt,
 			omap_obj->vaddr, omap_obj->roll);
 

drivers/gpu/drm/ttm/ttm_bo.c

@@ -140,8 +140,8 @@ static void ttm_bo_release_list(struct kref *list_kref)
 	struct ttm_bo_device *bdev = bo->bdev;
 	size_t acc_size = bo->acc_size;
 
-	BUG_ON(atomic_read(&bo->list_kref.refcount));
+	BUG_ON(kref_read(&bo->list_kref));
-	BUG_ON(atomic_read(&bo->kref.refcount));
+	BUG_ON(kref_read(&bo->kref));
 	BUG_ON(atomic_read(&bo->cpu_writers));
 	BUG_ON(bo->mem.mm_node != NULL);
 	BUG_ON(!list_empty(&bo->lru));

drivers/gpu/drm/ttm/ttm_object.c

@@ -304,7 +304,7 @@ bool ttm_ref_object_exists(struct ttm_object_file *tfile,
 	 * Verify that the ref->obj pointer was actually valid!
 	 */
 	rmb();
-	if (unlikely(atomic_read(&ref->kref.refcount) == 0))
+	if (unlikely(kref_read(&ref->kref) == 0))
 		goto out_false;
 
 	rcu_read_unlock();

drivers/infiniband/hw/cxgb3/iwch_cm.h

@@ -55,14 +55,14 @@
 
 #define put_ep(ep) { \
 	PDBG("put_ep (via %s:%u) ep %p refcnt %d\n", __func__, __LINE__,  \
-	     ep, atomic_read(&((ep)->kref.refcount))); \
+	     ep, kref_read(&((ep)->kref))); \
-	WARN_ON(atomic_read(&((ep)->kref.refcount)) < 1); \
+	WARN_ON(kref_read(&((ep)->kref)) < 1); \
 	kref_put(&((ep)->kref), __free_ep); \
 }
 
 #define get_ep(ep) { \
 	PDBG("get_ep (via %s:%u) ep %p, refcnt %d\n", __func__, __LINE__, \
-	     ep, atomic_read(&((ep)->kref.refcount))); \
+	     ep, kref_read(&((ep)->kref))); \
 	kref_get(&((ep)->kref));  \
 }
 

drivers/infiniband/hw/cxgb3/iwch_qp.c

@@ -961,7 +961,7 @@ int iwch_modify_qp(struct iwch_dev *rhp, struct iwch_qp *qhp,
 	case IWCH_QP_STATE_RTS:
 		switch (attrs->next_state) {
 		case IWCH_QP_STATE_CLOSING:
-			BUG_ON(atomic_read(&qhp->ep->com.kref.refcount) < 2);
+			BUG_ON(kref_read(&qhp->ep->com.kref) < 2);
 			qhp->attr.state = IWCH_QP_STATE_CLOSING;
 			if (!internal) {
 				abort=0;

drivers/infiniband/hw/cxgb4/iw_cxgb4.h

@@ -654,14 +654,14 @@ enum c4iw_mmid_state {
 
 #define c4iw_put_ep(ep) { \
 	PDBG("put_ep (via %s:%u) ep %p refcnt %d\n", __func__, __LINE__,  \
-	     ep, atomic_read(&((ep)->kref.refcount))); \
+	     ep, kref_read(&((ep)->kref))); \
-	WARN_ON(atomic_read(&((ep)->kref.refcount)) < 1); \
+	WARN_ON(kref_read(&((ep)->kref)) < 1); \
 	kref_put(&((ep)->kref), _c4iw_free_ep); \
 }
 
 #define c4iw_get_ep(ep) { \
 	PDBG("get_ep (via %s:%u) ep %p, refcnt %d\n", __func__, __LINE__, \
-	     ep, atomic_read(&((ep)->kref.refcount))); \
+	     ep, kref_read(&((ep)->kref))); \
 	kref_get(&((ep)->kref));  \
 }
 void _c4iw_free_ep(struct kref *kref);

drivers/infiniband/hw/cxgb4/qp.c

@@ -1503,7 +1503,7 @@ int c4iw_modify_qp(struct c4iw_dev *rhp, struct c4iw_qp *qhp,
 	case C4IW_QP_STATE_RTS:
 		switch (attrs->next_state) {
 		case C4IW_QP_STATE_CLOSING:
-			BUG_ON(atomic_read(&qhp->ep->com.kref.refcount) < 2);
+			BUG_ON(kref_read(&qhp->ep->com.kref) < 2);
 			t4_set_wq_in_error(&qhp->wq);
 			set_state(qhp, C4IW_QP_STATE_CLOSING);
 			ep = qhp->ep;

drivers/infiniband/hw/usnic/usnic_ib_sysfs.c

@@ -80,7 +80,7 @@ usnic_ib_show_config(struct device *device, struct device_attribute *attr,
 	left = PAGE_SIZE;
 
 	mutex_lock(&us_ibdev->usdev_lock);
-	if (atomic_read(&us_ibdev->vf_cnt.refcount) > 0) {
+	if (kref_read(&us_ibdev->vf_cnt) > 0) {
 		char *busname;
 
 		/*
@@ -99,7 +99,7 @@ usnic_ib_show_config(struct device *device, struct device_attribute *attr,
 			PCI_FUNC(us_ibdev->pdev->devfn),
 			netdev_name(us_ibdev->netdev),
 			us_ibdev->ufdev->mac,
-			atomic_read(&us_ibdev->vf_cnt.refcount));
+			kref_read(&us_ibdev->vf_cnt));
 		UPDATE_PTR_LEFT(n, ptr, left);
 
 		for (res_type = USNIC_VNIC_RES_TYPE_EOL;
@@ -147,7 +147,7 @@ usnic_ib_show_max_vf(struct device *device, struct device_attribute *attr,
 	us_ibdev = container_of(device, struct usnic_ib_dev, ib_dev.dev);
 
 	return scnprintf(buf, PAGE_SIZE, "%u\n",
-			atomic_read(&us_ibdev->vf_cnt.refcount));
+			kref_read(&us_ibdev->vf_cnt));
 }
 
 static ssize_t

drivers/infiniband/hw/usnic/usnic_ib_verbs.c

@@ -291,11 +291,11 @@ int usnic_ib_query_device(struct ib_device *ibdev,
 	qp_per_vf = max(us_ibdev->vf_res_cnt[USNIC_VNIC_RES_TYPE_WQ],
 			us_ibdev->vf_res_cnt[USNIC_VNIC_RES_TYPE_RQ]);
 	props->max_qp = qp_per_vf *
-		atomic_read(&us_ibdev->vf_cnt.refcount);
+		kref_read(&us_ibdev->vf_cnt);
 	props->device_cap_flags = IB_DEVICE_PORT_ACTIVE_EVENT |
 		IB_DEVICE_SYS_IMAGE_GUID | IB_DEVICE_BLOCK_MULTICAST_LOOPBACK;
 	props->max_cq = us_ibdev->vf_res_cnt[USNIC_VNIC_RES_TYPE_CQ] *
-		atomic_read(&us_ibdev->vf_cnt.refcount);
+		kref_read(&us_ibdev->vf_cnt);
 	props->max_pd = USNIC_UIOM_MAX_PD_CNT;
 	props->max_mr = USNIC_UIOM_MAX_MR_CNT;
 	props->local_ca_ack_delay = 0;

drivers/misc/genwqe/card_dev.c

@@ -1396,7 +1396,7 @@ int genwqe_device_remove(struct genwqe_dev *cd)
 	 * application which will decrease this reference from
 	 * 1/unused to 0/illegal and not from 2/used 1/empty.
 	 */
-	rc = atomic_read(&cd->cdev_genwqe.kobj.kref.refcount);
+	rc = kref_read(&cd->cdev_genwqe.kobj.kref);
 	if (rc != 1) {
 		dev_err(&pci_dev->dev,
 			"[%s] err: cdev_genwqe...refcount=%d\n", __func__, rc);