[PATCH 004 of 11] knfsd: convert sk_reserved to atomic_t

From: NeilBrown
Date: Sun Jul 30 2006 - 20:42:15 EST



From: Greg Banks <gnb@xxxxxxxxxxxxxxxxx>

knfsd: 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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>

### Diffstat output
./include/linux/sunrpc/svcsock.h | 2 +-
./net/sunrpc/svcsock.c | 12 +++++-------
2 files changed, 6 insertions(+), 8 deletions(-)

diff .prev/include/linux/sunrpc/svcsock.h ./include/linux/sunrpc/svcsock.h
--- .prev/include/linux/sunrpc/svcsock.h 2006-07-31 10:00:30.000000000 +1000
+++ ./include/linux/sunrpc/svcsock.h 2006-07-31 10:00:44.000000000 +1000
@@ -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 .prev/net/sunrpc/svcsock.c ./net/sunrpc/svcsock.c
--- .prev/net/sunrpc/svcsock.c 2006-07-31 10:00:30.000000000 +1000
+++ ./net/sunrpc/svcsock.c 2006-07-31 10:00:44.000000000 +1000
@@ -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,

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);
}
@@ -1236,7 +1234,7 @@ svc_recv(struct svc_rqst *rqstp, long ti
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);
-
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