block: bsg: move atomic_t ref_count variable to refcount API

Currently, variable ref_count within the bsg_device struct is of
type atomic_t.  For variables being used as reference counters,
the refcount API should be used instead of atomic.  The newer
refcount API works to prevent counter overflows and use-after-free
bugs.  So, move this varable from the atomic API to refcount,
potentially avoiding the issues mentioned.

Signed-off-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bsg.c b/block/bsg.c
index db588add6ba6622b1495446b05f19ce0e5720bf8..9a442c23a715e2f8b53b8bb4209af912a3f45af3 100644 (file)
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -37,7 +37,7 @@ struct bsg_device {
        struct request_queue *queue;
        spinlock_t lock;
        struct hlist_node dev_list;
-       atomic_t ref_count;
+       refcount_t ref_count;
        char name[20];
        int max_queue;
 };
@@ -252,7 +252,7 @@ static int bsg_put_device(struct bsg_device *bd)
 
        mutex_lock(&bsg_mutex);
 
-       if (!atomic_dec_and_test(&bd->ref_count)) {
+       if (!refcount_dec_and_test(&bd->ref_count)) {
                mutex_unlock(&bsg_mutex);
                return 0;
        }
@@ -290,7 +290,7 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
 
        bd->queue = rq;
 
-       atomic_set(&bd->ref_count, 1);
+       refcount_set(&bd->ref_count, 1);
        hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 
        strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
@@ -308,7 +308,7 @@ static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 
        hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
                if (bd->queue == q) {
-                       atomic_inc(&bd->ref_count);
+                       refcount_inc(&bd->ref_count);
                        goto found;
                }
        }