[PATCH] knfsd: make nlmclnt_next_cookie SMP safe

The way we incremented the NLM cookie in nlmclnt_next_cookie was not thread
safe.  This patch changes the counter to an atomic_t

Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 6 insertions, 5 deletions

diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index 7e6f22e2a3b4..3d84f600b633 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -36,14 +36,14 @@ static const struct rpc_call_ops nlmclnt_cancel_ops;
 /*
  * Cookie counter for NLM requests
  */
-static u32      nlm_cookie = 0x1234;
+static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
 
-static inline void nlmclnt_next_cookie(struct nlm_cookie *c)
+void nlmclnt_next_cookie(struct nlm_cookie *c)
 {
-        memcpy(c->data, &nlm_cookie, 4);
-        memset(c->data+4, 0, 4);
+        u32     cookie = atomic_inc_return(&nlm_cookie);
+
+        memcpy(c->data, &cookie, 4);
         c->len=4;
-        nlm_cookie++;
 }
 
 static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index 7be7aeaeee58..a345650e5622 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -157,6 +157,7 @@ int		  nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
 u32               nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *);
 void              nlmclnt_recovery(struct nlm_host *);
 int               nlmclnt_reclaim(struct nlm_host *, struct file_lock *);
+void              nlmclnt_next_cookie(struct nlm_cookie *);
 
 /*
  * Host cache