[RFC PATCH 04/11] net-sysfs: Create rps_create_sock_flow_table

[Tom Herbert <tom@herbertland.com>]

Move code for writing a sock_flow_table to its own function so that it
can be called for other use cases.
---
 net/core/sysctl_net_core.c | 102 +++++++++++++++++++++----------------
 1 file changed, 57 insertions(+), 45 deletions(-)

diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index f93f8ace6c56..9c7d46fbb75a 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -46,66 +46,78 @@ int sysctl_devconf_inherit_init_net __read_mostly;
 EXPORT_SYMBOL(sysctl_devconf_inherit_init_net);
 
 #ifdef CONFIG_RPS
+static int rps_create_sock_flow_table(size_t size, size_t orig_size,
+				      struct rps_sock_flow_table *orig_table,
+				      bool force)
+{
+	struct rps_sock_flow_table *sock_table;
+	int i;
+
+	if (size) {
+		if (size > 1 << 29) {
+			/* Enforce limit to prevent overflow */
+			return -EINVAL;
+		}
+		size = roundup_pow_of_two(size);
+		if (size != orig_size || force) {
+			sock_table = vmalloc(RPS_SOCK_FLOW_TABLE_SIZE(size));
+			if (!sock_table)
+				return -ENOMEM;
+
+			sock_table->mask = size - 1;
+		} else {
+			sock_table = orig_table;
+		}
+
+		for (i = 0; i < size; i++)
+			sock_table->ents[i] = RPS_NO_CPU;
+	} else {
+		sock_table = NULL;
+	}
+
+	if (sock_table != orig_table) {
+		rcu_assign_pointer(rps_sock_flow_table, sock_table);
+		if (sock_table) {
+			static_branch_inc(&rps_needed);
+			static_branch_inc(&rfs_needed);
+		}
+		if (orig_table) {
+			static_branch_dec(&rps_needed);
+			static_branch_dec(&rfs_needed);
+			synchronize_rcu();
+			vfree(orig_table);
+		}
+	}
+
+	return 0;
+}
+
+static DEFINE_MUTEX(sock_flow_mutex);
+
 static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
 				void *buffer, size_t *lenp, loff_t *ppos)
 {
 	unsigned int orig_size, size;
-	int ret, i;
+	int ret;
 	struct ctl_table tmp = {
 		.data = &size,
 		.maxlen = sizeof(size),
 		.mode = table->mode
 	};
-	struct rps_sock_flow_table *orig_sock_table, *sock_table;
-	static DEFINE_MUTEX(sock_flow_mutex);
+	struct rps_sock_flow_table *sock_table;
 
 	mutex_lock(&sock_flow_mutex);
 
-	orig_sock_table = rcu_dereference_protected(rps_sock_flow_table,
-					lockdep_is_held(&sock_flow_mutex));
-	size = orig_size = orig_sock_table ? orig_sock_table->mask + 1 : 0;
+	sock_table = rcu_dereference_protected(rps_sock_flow_table,
+					       lockdep_is_held(&sock_flow_mutex));
+	size = sock_table ? sock_table->mask + 1 : 0;
+	orig_size = size;
 
 	ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);
 
-	if (write) {
-		if (size) {
-			if (size > 1<<29) {
-				/* Enforce limit to prevent overflow */
-				mutex_unlock(&sock_flow_mutex);
-				return -EINVAL;
-			}
-			size = roundup_pow_of_two(size);
-			if (size != orig_size) {
-				sock_table =
-				    vmalloc(RPS_SOCK_FLOW_TABLE_SIZE(size));
-				if (!sock_table) {
-					mutex_unlock(&sock_flow_mutex);
-					return -ENOMEM;
-				}
-				rps_cpu_mask = roundup_pow_of_two(nr_cpu_ids) - 1;
-				sock_table->mask = size - 1;
-			} else
-				sock_table = orig_sock_table;
-
-			for (i = 0; i < size; i++)
-				sock_table->ents[i] = RPS_NO_CPU;
-		} else
-			sock_table = NULL;
-
-		if (sock_table != orig_sock_table) {
-			rcu_assign_pointer(rps_sock_flow_table, sock_table);
-			if (sock_table) {
-				static_branch_inc(&rps_needed);
-				static_branch_inc(&rfs_needed);
-			}
-			if (orig_sock_table) {
-				static_branch_dec(&rps_needed);
-				static_branch_dec(&rfs_needed);
-				synchronize_rcu();
-				vfree(orig_sock_table);
-			}
-		}
-	}
+	if (write)
+		ret = rps_create_sock_flow_table(size, orig_size,
+						 sock_table, false);
 
 	mutex_unlock(&sock_flow_mutex);
 
-- 
2.25.1