Commit 60749cbe authored by NeilBrown's avatar NeilBrown Committed by Chuck Lever
Browse files

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: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 16ef80ee

fs/nfsd/nfsctl.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

		}

fs/nfsd/nfssvc.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

}

include/linux/sunrpc/svc.h

+2 −2
Original line number Diff line number Diff line
@@ -35,7 +35,7 @@ 
struct svc_pool {

	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 */

net/sunrpc/svc.c

+11 −20
Original line number Diff line number Diff line
@@ -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:

	if (pool && pool->sp_nrthreads) {

		set_bit(SP_VICTIM_REMAINS, &pool->sp_flags);

		set_bit(SP_NEED_VICTIM, &pool->sp_flags);

	if (!atomic_dec_and_test(&pool->sp_nrthreads))

		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;