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>

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 98dff8d..af692bf 100644 (file)
--- 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)
 {