ieee1394: csr1212: proper refcounting

At least since nodemgr got rid of coarse global locking, accesses to
struct csr1212_keyval's reference counter should be atomic and coupled
with proper barriers.  Also, calls to csr1212_keep_keyval(kv) should
occur before kv is being used.

(We probably should convert refcnt to struct kref, but how to keep
csr1212_destroy_keyval's implementation non-recursively then?)

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/ieee1394/csr1212.h b/drivers/ieee1394/csr1212.h
index df909ce66304..043039fc63ec 100644
--- a/drivers/ieee1394/csr1212.h
+++ b/drivers/ieee1394/csr1212.h
@@ -32,6 +32,7 @@
 
 #include <linux/types.h>
 #include <linux/slab.h>
+#include <asm/atomic.h>
 
 #define CSR1212_MALLOC(size)    kmalloc((size), GFP_KERNEL)
 #define CSR1212_FREE(ptr)       kfree(ptr)
@@ -149,7 +150,7 @@ struct csr1212_keyval {
                 struct csr1212_directory directory;
         } value;
         struct csr1212_keyval *associate;
-        int refcnt;
+        atomic_t refcnt;
 
         /* used in generating and/or parsing CSR image */
         struct csr1212_keyval *next, *prev;     /* flat list of CSR elements */
@@ -350,7 +351,8 @@ csr1212_get_keyval(struct csr1212_csr *csr, struct csr1212_keyval *kv);
  * need for code to retain a keyval that has been parsed. */
 static inline void csr1212_keep_keyval(struct csr1212_keyval *kv)
 {
-        kv->refcnt++;
+        atomic_inc(&kv->refcnt);
+        smp_mb__after_atomic_inc();
 }