sunrpc: change sp_nrthreads from atomic_t to unsigned int.

sp_nrthreads is only ever accessed under the service mutex
  nlmsvc_mutex nfs_callback_mutex nfsd_mutex
so these is no need for it to be an atomic_t.

The fact that all code using it is single-threaded means that we can
simplify svc_pool_victim and remove the temporary elevation of
sp_nrthreads.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 965519995aeb56154c67c52a133bd6d03e29395c..1c9e5b4bcb0ae487bc0094d252761e9b6e5cf06b 100644 (file)
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1769,7 +1769,7 @@ int nfsd_nl_threads_get_doit(struct sk_buff *skb, struct genl_info *info)
                        struct svc_pool *sp = &nn->nfsd_serv->sv_pools[i];
 
                        err = nla_put_u32(skb, NFSD_A_SERVER_THREADS,
-                                         atomic_read(&sp->sp_nrthreads));
+                                         sp->sp_nrthreads);
                        if (err)
                                goto err_unlock;
                }

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 5bc4dc60ea4c2e5acc3323b864cae91406476688..b1dc3404173b38cef07b020dd5d114cecb860f66 100644 (file)
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -641,7 +641,7 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
 
        if (serv)
                for (i = 0; i < serv->sv_nrpools && i < n; i++)
-                       nthreads[i] = atomic_read(&serv->sv_pools[i].sp_nrthreads);
+                       nthreads[i] = serv->sv_pools[i].sp_nrthreads;
        return 0;
 }
 

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index e4fa25fafa9795bfca79a6af802907e7b3e106da..99e9345d829e82c947e4c25588149b03d0ba91fc 100644 (file)
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -33,9 +33,9 @@
  * node traffic on multi-node NUMA NFS servers.
  */
 struct svc_pool {
-       unsigned int            sp_id;          /* pool id; also node id on NUMA */
+       unsigned int            sp_id;          /* pool id; also node id on NUMA */
        struct lwq              sp_xprts;       /* pending transports */
-       atomic_t                sp_nrthreads;   /* # of threads in pool */
+       unsigned int            sp_nrthreads;   /* # of threads in pool */
        struct list_head        sp_all_threads; /* all server threads */
        struct llist_head       sp_idle_threads; /* idle server threads */
 

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 2e148137376da5ffc0fc7fa4bbf624127592ca50..9442ebf38bbd930aabec87b38a04e3f785e87af6 100644 (file)
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -725,7 +725,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
        serv->sv_nrthreads += 1;
        spin_unlock_bh(&serv->sv_lock);
 
-       atomic_inc(&pool->sp_nrthreads);
+       pool->sp_nrthreads += 1;
 
        /* Protected by whatever lock the service uses when calling
         * svc_set_num_threads()
@@ -780,31 +780,22 @@ svc_pool_victim(struct svc_serv *serv, struct svc_pool *target_pool,
        struct svc_pool *pool;
        unsigned int i;
 
-retry:
        pool = target_pool;
 
-       if (pool != NULL) {
-               if (atomic_inc_not_zero(&pool->sp_nrthreads))
-                       goto found_pool;
-               return NULL;
-       } else {
+       if (!pool) {
                for (i = 0; i < serv->sv_nrpools; i++) {
                        pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];
-                       if (atomic_inc_not_zero(&pool->sp_nrthreads))
-                               goto found_pool;
+                       if (pool->sp_nrthreads)
+                               break;
                }
-               return NULL;
        }
 
-found_pool:
-       set_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
-       set_bit(SP_NEED_VICTIM, &pool->sp_flags);
-       if (!atomic_dec_and_test(&pool->sp_nrthreads))
+       if (pool && pool->sp_nrthreads) {
+               set_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
+               set_bit(SP_NEED_VICTIM, &pool->sp_flags);
                return pool;
-       /* Nothing left in this pool any more */
-       clear_bit(SP_NEED_VICTIM, &pool->sp_flags);
-       clear_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
-       goto retry;
+       }
+       return NULL;
 }
 
 static int
@@ -883,7 +874,7 @@ svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
        if (!pool)
                nrservs -= serv->sv_nrthreads;
        else
-               nrservs -= atomic_read(&pool->sp_nrthreads);
+               nrservs -= pool->sp_nrthreads;
 
        if (nrservs > 0)
                return svc_start_kthreads(serv, pool, nrservs);
@@ -967,7 +958,7 @@ svc_exit_thread(struct svc_rqst *rqstp)
 
        list_del_rcu(&rqstp->rq_all);
 
-       atomic_dec(&pool->sp_nrthreads);
+       pool->sp_nrthreads -= 1;
 
        spin_lock_bh(&serv->sv_lock);
        serv->sv_nrthreads -= 1;