Reference counters are preferred to use refcount_t instead of
atomic_t.
This is because the implementation of refcount_t can prevent
overflows and detect possible use-after-free.
So convert atomic_t ref counters to refcount_t.
Signed-off-by: Chuhong Yuan <hslester96@xxxxxxxxx>
---
drivers/block/xen-blkback/common.h | 7 ++++---
drivers/block/xen-blkback/xenbus.c | 2 +-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 1d3002d773f7..9db5f3586fb4 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -35,6 +35,7 @@
#include <linux/wait.h>
#include <linux/io.h>
#include <linux/rbtree.h>
+#include <linux/refcount.h>
#include <asm/setup.h>
#include <asm/pgalloc.h>
#include <asm/hypervisor.h>
@@ -309,7 +310,7 @@ struct xen_blkif {
struct xen_vbd vbd;
/* Back pointer to the backend_info. */
struct backend_info *be;
- atomic_t refcnt;
+ refcount_t refcnt;
/* for barrier (drain) requests */
struct completion drain_complete;
atomic_t drain;
@@ -362,10 +363,10 @@ struct pending_req {
(_v)->bdev->bd_part->nr_sects : \
get_capacity((_v)->bdev->bd_disk))
-#define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
+#define xen_blkif_get(_b) (refcount_inc(&(_b)->refcnt))
#define xen_blkif_put(_b) \
do { \
- if (atomic_dec_and_test(&(_b)->refcnt)) \
+ if (refcount_dec_and_test(&(_b)->refcnt)) \
schedule_work(&(_b)->free_work);\
} while (0)
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 3ac6a5d18071..ecc5f9c5bf3f 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -169,7 +169,7 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
return ERR_PTR(-ENOMEM);
blkif->domid = domid;
- atomic_set(&blkif->refcnt, 1);
+ refcount_set(&blkif->refcnt, 1);
init_completion(&blkif->drain_complete);
INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
--
2.20.1
