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SUNRPC: Clean up svc_set_num_threads

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Document the API contract and remove stale or obvious comments.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2023-07-10 12:42:33 -04:00
parent f208e9508a
commit d2f0ef1cbf
1 changed files with 25 additions and 35 deletions
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60
net/sunrpc/svc.c
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@ -723,23 +723,14 @@ bool svc_pool_wake_idle_thread(struct svc_pool *pool)
return false;
}
/*
* Choose a pool in which to create a new thread, for svc_set_num_threads
*/
static inline struct svc_pool *
choose_pool(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
static struct svc_pool *
svc_pool_next(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
{
if (pool != NULL)
return pool;
return &serv->sv_pools[(*state)++ % serv->sv_nrpools];
return pool ? pool : &serv->sv_pools[(*state)++ % serv->sv_nrpools];
}
/*
* Choose a thread to kill, for svc_set_num_threads
*/
static inline struct task_struct *
choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
static struct task_struct *
svc_pool_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
{
unsigned int i;
struct task_struct *task = NULL;
@ -747,7 +738,6 @@ choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
if (pool != NULL) {
spin_lock_bh(&pool->sp_lock);
} else {
/* choose a pool in round-robin fashion */
for (i = 0; i < serv->sv_nrpools; i++) {
pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];
spin_lock_bh(&pool->sp_lock);
@ -762,21 +752,15 @@ found_pool:
if (!list_empty(&pool->sp_all_threads)) {
struct svc_rqst *rqstp;
/*
* Remove from the pool->sp_all_threads list
* so we don't try to kill it again.
*/
rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all);
set_bit(RQ_VICTIM, &rqstp->rq_flags);
list_del_rcu(&rqstp->rq_all);
task = rqstp->rq_task;
}
spin_unlock_bh(&pool->sp_lock);
return task;
}
/* create new threads */
static int
svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
@ -788,13 +772,12 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
do {
nrservs--;
chosen_pool = choose_pool(serv, pool, &state);
chosen_pool = svc_pool_next(serv, pool, &state);
node = svc_pool_map_get_node(chosen_pool->sp_id);
rqstp = svc_prepare_thread(serv, chosen_pool, node);
if (IS_ERR(rqstp))
return PTR_ERR(rqstp);
task = kthread_create_on_node(serv->sv_threadfn, rqstp,
node, "%s", serv->sv_name);
if (IS_ERR(task)) {
@ -813,15 +796,6 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
return 0;
}
/*
* Create or destroy enough new threads to make the number
* of threads the given number. If `pool' is non-NULL, applies
* only to threads in that pool, otherwise round-robins between
* all pools. Caller must ensure that mutual exclusion between this and
* server startup or shutdown.
*/
/* destroy old threads */
static int
svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
@ -829,9 +803,8 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
struct task_struct *task;
unsigned int state = serv->sv_nrthreads-1;
/* destroy old threads */
do {
task = choose_victim(serv, pool, &state);
task = svc_pool_victim(serv, pool, &state);
if (task == NULL)
break;
rqstp = kthread_data(task);
@ -843,6 +816,23 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
return 0;
}
/**
* svc_set_num_threads - adjust number of threads per RPC service
* @serv: RPC service to adjust
* @pool: Specific pool from which to choose threads, or NULL
* @nrservs: New number of threads for @serv (0 or less means kill all threads)
*
* Create or destroy threads to make the number of threads for @serv the
* given number. If @pool is non-NULL, change only threads in that pool;
* otherwise, round-robin between all pools for @serv. @serv's
* sv_nrthreads is adjusted for each thread created or destroyed.
*
* Caller must ensure mutual exclusion between this and server startup or
* shutdown.
*
* Returns zero on success or a negative errno if an error occurred while
* starting a thread.
*/
int
svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{