Commit 93aa619e authored by NeilBrown's avatar NeilBrown Committed by Chuck Lever
Browse files

SUNRPC: always treat sv_nrpools==1 as "not pooled" 



Currently 'pooled' services hold a reference on the pool_map, and
'unpooled' services do not.
svc_destroy() uses the presence of ->svo_function (via
svc_serv_is_pooled()) to determine if the reference should be dropped.
There is no direct correlation between being pooled and the use of
svo_function, though in practice, lockd is the only non-pooled service,
and the only one not to use svo_function.

This is untidy and would cause problems if we changed lockd to use
svc_set_num_threads(), which requires the use of ->svo_function.

So change the test for "is the service pooled" to "is sv_nrpools > 1".

This means that when svc_pool_map_get() returns 1, it must NOT take a
reference to the pool.

We discard svc_serv_is_pooled(), and test sv_nrpools directly.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent cf0e124e

net/sunrpc/svc.c

+29 −25
Original line number Diff line number Diff line
@@ -37,8 +37,6 @@ 


static void svc_unregister(const struct svc_serv *serv, struct net *net);



#define svc_serv_is_pooled(serv)    ((serv)->sv_ops->svo_function)



#define SVC_POOL_DEFAULT	SVC_POOL_GLOBAL



/*
@@ -240,8 +238,10 @@ svc_pool_map_init_pernode(struct svc_pool_map *m) 


/*

 * Add a reference to the global map of cpus to pools (and

 * vice versa).  Initialise the map if we're the first user.

 * Returns the number of pools.

 * vice versa) if pools are in use.

 * Initialise the map if we're the first user.

 * Returns the number of pools. If this is '1', no reference

 * was taken.

 */

static unsigned int

svc_pool_map_get(void)
@@ -253,6 +253,7 @@ svc_pool_map_get(void) 


	if (m->count++) {

		mutex_unlock(&svc_pool_map_mutex);

		WARN_ON_ONCE(m->npools <= 1);

		return m->npools;

	}
@@ -268,29 +269,36 @@ svc_pool_map_get(void) 
		break;

	}



	if (npools < 0) {

	if (npools <= 0) {

		/* default, or memory allocation failure */

		npools = 1;

		m->mode = SVC_POOL_GLOBAL;

	}

	m->npools = npools;



	if (npools == 1)

		/* service is unpooled, so doesn't hold a reference */

		m->count--;



	mutex_unlock(&svc_pool_map_mutex);

	return m->npools;

	return npools;

}



/*

 * Drop a reference to the global map of cpus to pools.

 * Drop a reference to the global map of cpus to pools, if

 * pools were in use, i.e. if npools > 1.

 * When the last reference is dropped, the map data is

 * freed; this allows the sysadmin to change the pool

 * mode using the pool_mode module option without

 * rebooting or re-loading sunrpc.ko.

 */

static void

svc_pool_map_put(void)

svc_pool_map_put(int npools)

{

	struct svc_pool_map *m = &svc_pool_map;



	if (npools <= 1)

		return;

	mutex_lock(&svc_pool_map_mutex);



	if (!--m->count) {
@@ -359,12 +367,9 @@ svc_pool_for_cpu(struct svc_serv *serv, int cpu) 
	struct svc_pool_map *m = &svc_pool_map;

	unsigned int pidx = 0;



	/*

	 * An uninitialised map happens in a pure client when

	 * lockd is brought up, so silently treat it the

	 * same as SVC_POOL_GLOBAL.

	 */

	if (svc_serv_is_pooled(serv)) {

	if (serv->sv_nrpools <= 1)

		return serv->sv_pools;



	switch (m->mode) {

	case SVC_POOL_PERCPU:

		pidx = m->to_pool[cpu];
@@ -373,7 +378,7 @@ svc_pool_for_cpu(struct svc_serv *serv, int cpu) 
		pidx = m->to_pool[cpu_to_node(cpu)];

		break;

	}

	}



	return &serv->sv_pools[pidx % serv->sv_nrpools];

}
@@ -526,7 +531,7 @@ svc_create_pooled(struct svc_program *prog, unsigned int bufsize, 
		goto out_err;

	return serv;

out_err:

	svc_pool_map_put();

	svc_pool_map_put(npools);

	return NULL;

}

EXPORT_SYMBOL_GPL(svc_create_pooled);
@@ -561,8 +566,7 @@ svc_destroy(struct kref *ref) 


	cache_clean_deferred(serv);



	if (svc_serv_is_pooled(serv))

		svc_pool_map_put();

	svc_pool_map_put(serv->sv_nrpools);



	kfree(serv->sv_pools);

	kfree(serv);