[Xen-devel] [PATCH 02/29] drivers, firewire: convert fw_node.ref_count from atomic_t to refcount_t

[Elena Reshetova <elena.reshetova@xxxxxxxxx>]

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
 drivers/firewire/core-topology.c | 2 +-
 drivers/firewire/core.h          | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core-topology.c
index 0de8350..939d259 100644
--- a/drivers/firewire/core-topology.c
+++ b/drivers/firewire/core-topology.c
@@ -124,7 +124,7 @@ static struct fw_node *fw_node_create(u32 sid, int 
port_count, int color)
        node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);
        node->port_count = port_count;
 
-       atomic_set(&node->ref_count, 1);
+       refcount_set(&node->ref_count, 1);
        INIT_LIST_HEAD(&node->link);
 
        return node;
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index e1480ff6..c07962e 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -12,7 +12,7 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 
 struct device;
 struct fw_card;
@@ -184,7 +184,7 @@ struct fw_node {
                         * local node to this node. */
        u8 max_depth:4; /* Maximum depth to any leaf node */
        u8 max_hops:4;  /* Max hops in this sub tree */
-       atomic_t ref_count;
+       refcount_t ref_count;
 
        /* For serializing node topology into a list. */
        struct list_head link;
@@ -197,14 +197,14 @@ struct fw_node {
 
 static inline struct fw_node *fw_node_get(struct fw_node *node)
 {
-       atomic_inc(&node->ref_count);
+       refcount_inc(&node->ref_count);
 
        return node;
 }
 
 static inline void fw_node_put(struct fw_node *node)
 {
-       if (atomic_dec_and_test(&node->ref_count))
+       if (refcount_dec_and_test(&node->ref_count))
                kfree(node);
 }
 
-- 
2.7.4


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