[PATCH 4.9 01/77] SUNRPC: Refactor svc_set_num_threads()

Greg Kroah-Hartman
2017-09-24T20:37:00Z

From: Trond Myklebust <trond.myklebust@primarydata.com>

commit 9e0d87680d689f1758185851c3da6eafb16e71e1 upstream.

Refactor to separate out the functions of starting and stopping threads
so that they can be used in other helpers.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Tested-and-reviewed-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Cc: Jan Hudoba <kernel@jahu.sk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/sunrpc/svc.c | 96 +++++++++++++++++++++++++++++++++----------------------
1 file changed, 58 insertions(+), 38 deletions(-)

--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -702,59 +702,32 @@ found_pool:
return task;
}

-/*
- * 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.
- *
- * Destroying threads relies on the service threads filling in
- * rqstp->rq_task, which only the nfs ones do. Assumes the serv
- * has been created using svc_create_pooled().
- *
- * Based on code that used to be in nfsd_svc() but tweaked
- * to be pool-aware.
- */
-int
-svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
+/* create new threads */
+static int
+svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
{
struct svc_rqst *rqstp;
struct task_struct *task;
struct svc_pool *chosen_pool;
- int error = 0;
unsigned int state = serv->sv_nrthreads-1;
int node;

- if (pool == NULL) {
- /* The -1 assumes caller has done a svc_get() */
- nrservs -= (serv->sv_nrthreads-1);
- } else {
- spin_lock_bh(&pool->sp_lock);
- nrservs -= pool->sp_nrthreads;
- spin_unlock_bh(&pool->sp_lock);
- }
-
- /* create new threads */
- while (nrservs > 0) {
+ do {
nrservs--;
chosen_pool = choose_pool(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)) {
- error = PTR_ERR(rqstp);
- break;
- }
+ if (IS_ERR(rqstp))
+ return PTR_ERR(rqstp);

__module_get(serv->sv_ops->svo_module);
task = kthread_create_on_node(serv->sv_ops->svo_function, rqstp,
node, "%s", serv->sv_name);
if (IS_ERR(task)) {
- error = PTR_ERR(task);
module_put(serv->sv_ops->svo_module);
svc_exit_thread(rqstp);
- break;
+ return PTR_ERR(task);
}

rqstp->rq_task = task;
@@ -763,15 +736,62 @@ svc_set_num_threads(struct svc_serv *ser

svc_sock_update_bufs(serv);
wake_up_process(task);
- }
+ } while (nrservs > 0);
+
+ return 0;
+}
+
+
+/* destroy old threads */
+static int
+svc_signal_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 */
- while (nrservs < 0 &&
- (task = choose_victim(serv, pool, &state)) != NULL) {
+ do {
+ task = choose_victim(serv, pool, &state);
+ if (task == NULL)
+ break;
send_sig(SIGINT, task, 1);
nrservs++;
+ } while (nrservs < 0);
+
+ 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.
+ *
+ * Destroying threads relies on the service threads filling in
+ * rqstp->rq_task, which only the nfs ones do. Assumes the serv
+ * has been created using svc_create_pooled().
+ *
+ * Based on code that used to be in nfsd_svc() but tweaked
+ * to be pool-aware.
+ */
+int
+svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
+{
+ if (pool == NULL) {
+ /* The -1 assumes caller has done a svc_get() */
+ nrservs -= (serv->sv_nrthreads-1);
+ } else {
+ spin_lock_bh(&pool->sp_lock);
+ nrservs -= pool->sp_nrthreads;
+ spin_unlock_bh(&pool->sp_lock);
}

- return error;
+ if (nrservs > 0)
+ return svc_start_kthreads(serv, pool, nrservs);
+ if (nrservs < 0)
+ return svc_signal_kthreads(serv, pool, nrservs);
+ return 0;
}
EXPORT_SYMBOL_GPL(svc_set_num_threads);