[PATCH] knfsd: convert sk_reserved to atomic_t

Convert the svc_sock->sk_reserved variable from an int protected by
svc_serv->sv_lock, to an atomic.  This reduces (by 1) the number of places we
need to take the (effectively global) svc_serv->sv_lock.

Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
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, 8 deletions

diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index 7766a1001660..7154e71c6d1f 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -34,7 +34,7 @@ struct svc_sock {
 #define SK_OLD          9                       /* used for temp socket aging mark+sweep */
 #define SK_DETACHED     10                      /* detached from tempsocks list */
 
-        int                     sk_reserved;    /* space on outq that is reserved */
+        atomic_t                sk_reserved;    /* space on outq that is reserved */
 
         spinlock_t              sk_defer_lock;  /* protects sk_deferred */
         struct list_head        sk_deferred;    /* deferred requests that need to
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index bdb5c2841db7..88b51c4ecb8b 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -177,13 +177,13 @@ svc_sock_enqueue(struct svc_sock *svsk)
         }
 
         set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
-        if (((svsk->sk_reserved + serv->sv_bufsz)*2
+        if (((atomic_read(&svsk->sk_reserved) + serv->sv_bufsz)*2
              > svc_sock_wspace(svsk))
             && !test_bit(SK_CLOSE, &svsk->sk_flags)
             && !test_bit(SK_CONN, &svsk->sk_flags)) {
                 /* Don't enqueue while not enough space for reply */
                 dprintk("svc: socket %p  no space, %d*2 > %ld, not enqueued\n",
-                        svsk->sk_sk, svsk->sk_reserved+serv->sv_bufsz,
+                        svsk->sk_sk, atomic_read(&svsk->sk_reserved)+serv->sv_bufsz,
                         svc_sock_wspace(svsk));
                 goto out_unlock;
         }
@@ -209,7 +209,7 @@ svc_sock_enqueue(struct svc_sock *svsk)
                 rqstp->rq_sock = svsk;
                 atomic_inc(&svsk->sk_inuse);
                 rqstp->rq_reserved = serv->sv_bufsz;
-                svsk->sk_reserved += rqstp->rq_reserved;
+                atomic_add(rqstp->rq_reserved, &svsk->sk_reserved);
                 wake_up(&rqstp->rq_wait);
         } else {
                 dprintk("svc: socket %p put into queue\n", svsk->sk_sk);
@@ -271,10 +271,8 @@ void svc_reserve(struct svc_rqst *rqstp, int space)
 
         if (space < rqstp->rq_reserved) {
                 struct svc_sock *svsk = rqstp->rq_sock;
-                spin_lock_bh(&svsk->sk_server->sv_lock);
-                svsk->sk_reserved -= (rqstp->rq_reserved - space);
+                atomic_sub((rqstp->rq_reserved - space), &svsk->sk_reserved);
                 rqstp->rq_reserved = space;
-                spin_unlock_bh(&svsk->sk_server->sv_lock);
 
                 svc_sock_enqueue(svsk);
         }
@@ -1226,7 +1224,7 @@ svc_recv(struct svc_rqst *rqstp, long timeout)
                 rqstp->rq_sock = svsk;
                 atomic_inc(&svsk->sk_inuse);
                 rqstp->rq_reserved = serv->sv_bufsz;    
-                svsk->sk_reserved += rqstp->rq_reserved;
+                atomic_add(rqstp->rq_reserved, &svsk->sk_reserved);
         } else {
                 /* No data pending. Go to sleep */
                 svc_serv_enqueue(serv, rqstp);