[PATCH 003 of 11] knfsd: use new lock for svc_sock deferred list

From: NeilBrown
Date: Sun Jul 30 2006 - 20:43:19 EST



From: Greg Banks <gnb@xxxxxxxxxxxxxxxxx>

knfsd: Protect the svc_sock->sk_deferred list with a new
lock svc_sock->sk_defer_lock instead of svc_serv->sv_lock.
Using the more fine-grained lock reduces the number of places
we need to take the svc_serv lock.

Signed-off-by: Greg Banks <gnb@xxxxxxxxxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>

### Diffstat output
./include/linux/sunrpc/svcsock.h | 1 +
./net/sunrpc/svcsock.c | 12 ++++++------
2 files changed, 7 insertions(+), 6 deletions(-)

diff .prev/include/linux/sunrpc/svcsock.h ./include/linux/sunrpc/svcsock.h
--- .prev/include/linux/sunrpc/svcsock.h 2006-07-31 09:58:07.000000000 +1000
+++ ./include/linux/sunrpc/svcsock.h 2006-07-31 10:00:30.000000000 +1000
@@ -36,6 +36,7 @@ struct svc_sock {

int 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
* be revisted */
struct mutex sk_mutex; /* to serialize sending data */

diff .prev/net/sunrpc/svcsock.c ./net/sunrpc/svcsock.c
--- .prev/net/sunrpc/svcsock.c 2006-07-31 09:58:07.000000000 +1000
+++ ./net/sunrpc/svcsock.c 2006-07-31 10:00:30.000000000 +1000
@@ -47,6 +47,7 @@
/* SMP locking strategy:
*
* svc_serv->sv_lock protects most stuff for that service.
+ * svc_sock->sk_defer_lock protects the svc_sock->sk_deferred list
*
* Some flags can be set to certain values at any time
* providing that certain rules are followed:
@@ -1426,6 +1427,7 @@ svc_setup_socket(struct svc_serv *serv,
svsk->sk_server = serv;
atomic_set(&svsk->sk_inuse, 0);
svsk->sk_lastrecv = get_seconds();
+ spin_lock_init(&svsk->sk_defer_lock);
INIT_LIST_HEAD(&svsk->sk_deferred);
INIT_LIST_HEAD(&svsk->sk_ready);
mutex_init(&svsk->sk_mutex);
@@ -1606,7 +1608,6 @@ svc_makesock(struct svc_serv *serv, int
static void svc_revisit(struct cache_deferred_req *dreq, int too_many)
{
struct svc_deferred_req *dr = container_of(dreq, struct svc_deferred_req, handle);
- struct svc_serv *serv = dreq->owner;
struct svc_sock *svsk;

if (too_many) {
@@ -1617,9 +1618,9 @@ static void svc_revisit(struct cache_def
dprintk("revisit queued\n");
svsk = dr->svsk;
dr->svsk = NULL;
- spin_lock_bh(&serv->sv_lock);
+ spin_lock_bh(&svsk->sk_defer_lock);
list_add(&dr->handle.recent, &svsk->sk_deferred);
- spin_unlock_bh(&serv->sv_lock);
+ spin_unlock_bh(&svsk->sk_defer_lock);
set_bit(SK_DEFERRED, &svsk->sk_flags);
svc_sock_enqueue(svsk);
svc_sock_put(svsk);
@@ -1679,11 +1680,10 @@ static int svc_deferred_recv(struct svc_
static struct svc_deferred_req *svc_deferred_dequeue(struct svc_sock *svsk)
{
struct svc_deferred_req *dr = NULL;
- struct svc_serv *serv = svsk->sk_server;

if (!test_bit(SK_DEFERRED, &svsk->sk_flags))
return NULL;
- spin_lock_bh(&serv->sv_lock);
+ spin_lock_bh(&svsk->sk_defer_lock);
clear_bit(SK_DEFERRED, &svsk->sk_flags);
if (!list_empty(&svsk->sk_deferred)) {
dr = list_entry(svsk->sk_deferred.next,
@@ -1692,6 +1692,6 @@ static struct svc_deferred_req *svc_defe
list_del_init(&dr->handle.recent);
set_bit(SK_DEFERRED, &svsk->sk_flags);
}
- spin_unlock_bh(&serv->sv_lock);
+ spin_unlock_bh(&svsk->sk_defer_lock);
return dr;
}
-
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