[PATCH 16/22] [lockd] make nlmclnt_next_cookie SMP safe

[PATCH 16/22] [lockd] make nlmclnt_next_cookie SMP safe

[Olaf Kirch]

From: Olaf Kirch <okir@suse.de>
Subject: [lockd] 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>

 fs/lockd/clntproc.c         |   10 +++++-----
 include/linux/lockd/lockd.h |    3 ++-
 2 files changed, 7 insertions(+), 6 deletions(-)

Index: build/fs/lockd/clntproc.c
===================================================================
--- build.orig/fs/lockd/clntproc.c
+++ build/fs/lockd/clntproc.c
@@ -36,14 +36,14 @@ static const struct rpc_call_ops nlmclnt
 /*
  * 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)
Index: build/include/linux/lockd/lockd.h
===================================================================
--- build.orig/include/linux/lockd/lockd.h
+++ build/include/linux/lockd/lockd.h
@@ -159,6 +159,7 @@ int		  nlmclnt_block(struct nlm_wait *bl
 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

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