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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: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
NeilBrown 2021-11-29 15:51:25 +11:00 committed by Chuck Lever
parent cf0e124e0a
commit 93aa619eb0
1 changed files with 29 additions and 25 deletions
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54
net/sunrpc/svc.c
View File

@ -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) {
@ -359,21 +367,18 @@ 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)) {
switch (m->mode) {
case SVC_POOL_PERCPU:
pidx = m->to_pool[cpu];
break;
case SVC_POOL_PERNODE:
pidx = m->to_pool[cpu_to_node(cpu)];
break;
}
if (serv->sv_nrpools <= 1)
return serv->sv_pools;
switch (m->mode) {
case SVC_POOL_PERCPU:
pidx = m->to_pool[cpu];
break;
case SVC_POOL_PERNODE:
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);