linux-kernel - [PATCH 4.9 01/77] SUNRPC: Refactor svc_set_num

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Message-Id: <20170924203242.955147662@linuxfoundation.org>
Date:   Sun, 24 Sep 2017 22:31:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Trond Myklebust <trond.myklebust@...marydata.com>,
        "J. Bruce Fields" <bfields@...hat.com>, Jan Hudoba <kernel@...u.sk>
Subject: [PATCH 4.9 01/77] SUNRPC: Refactor svc_set_num_threads()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <trond.myklebust@...marydata.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@...marydata.com>
Tested-and-reviewed-by: Kinglong Mee <kinglongmee@...il.com>
Signed-off-by: J. Bruce Fields <bfields@...hat.com>
Cc: Jan Hudoba <kernel@...u.sk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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);