From d2f0ef1cbf37e396ef9c57a30c004ebe65cdbca9 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Mon, 10 Jul 2023 12:42:33 -0400 Subject: [PATCH] SUNRPC: Clean up svc_set_num_threads Document the API contract and remove stale or obvious comments. Reviewed-by: Jeff Layton Reviewed-by: NeilBrown Signed-off-by: Chuck Lever --- net/sunrpc/svc.c | 60 +++++++++++++++++++++++--------------------------------- 1 file changed, 25 insertions(+), 35 deletions(-) diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 98dff8d..af692bf 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -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) { -- 2.7.4