From d2f0ef1cbf37e396ef9c57a30c004ebe65cdbca9 Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@oracle.com>
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 <jlayton@redhat.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
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 98dff8dfbac89..af692bff44ab6 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)
{
--
2.30.2