net-sysctl: factor-out rpm mask manipulation helpers

Will simplify the following patch. No functional change
intended.

Signed-off-by: Paolo Abeni <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Reviewed-by: Eric Dumazet <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

net/core/dev.h

···
 struct netdev_bpf;
 struct netdev_phys_item_id;
 struct netlink_ext_ack;
+struct cpumask;
 
 /* Random bits of netdevice that don't need to be exposed */
 #define FLOW_LIMIT_HISTORY	(1 << 7)  /* must be ^2 and !overflow buckets */
···
 	WRITE_ONCE(dev->gro_ipv4_max_size, size);
 }
 
+int rps_cpumask_housekeeping(struct cpumask *mask);
 #endif

net/core/net-sysfs.c

···
 	return len < PAGE_SIZE ? len : -EINVAL;
 }
 
-static ssize_t store_rps_map(struct netdev_rx_queue *queue,
-			     const char *buf, size_t len)
+static int netdev_rx_queue_set_rps_mask(struct netdev_rx_queue *queue,
+					cpumask_var_t mask)
 {
-	struct rps_map *old_map, *map;
-	cpumask_var_t mask;
-	int err, cpu, i;
 	static DEFINE_MUTEX(rps_map_mutex);
-
-	if (!capable(CAP_NET_ADMIN))
-		return -EPERM;
-
-	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
-		return -ENOMEM;
-
-	err = bitmap_parse(buf, len, cpumask_bits(mask), nr_cpumask_bits);
-	if (err) {
-		free_cpumask_var(mask);
-		return err;
-	}
-
-	if (!cpumask_empty(mask)) {
-		cpumask_and(mask, mask, housekeeping_cpumask(HK_TYPE_DOMAIN));
-		cpumask_and(mask, mask, housekeeping_cpumask(HK_TYPE_WQ));
-		if (cpumask_empty(mask)) {
-			free_cpumask_var(mask);
-			return -EINVAL;
-		}
-	}
+	struct rps_map *old_map, *map;
+	int cpu, i;
 
 	map = kzalloc(max_t(unsigned int,
 			    RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES),
 		      GFP_KERNEL);
-	if (!map) {
-		free_cpumask_var(mask);
+	if (!map)
 		return -ENOMEM;
-	}
 
 	i = 0;
 	for_each_cpu_and(cpu, mask, cpu_online_mask)
···
 
 	if (old_map)
 		kfree_rcu(old_map, rcu);
+	return 0;
+}
 
+int rps_cpumask_housekeeping(struct cpumask *mask)
+{
+	if (!cpumask_empty(mask)) {
+		cpumask_and(mask, mask, housekeeping_cpumask(HK_TYPE_DOMAIN));
+		cpumask_and(mask, mask, housekeeping_cpumask(HK_TYPE_WQ));
+		if (cpumask_empty(mask))
+			return -EINVAL;
+	}
+	return 0;
+}
+
+static ssize_t store_rps_map(struct netdev_rx_queue *queue,
+			     const char *buf, size_t len)
+{
+	cpumask_var_t mask;
+	int err;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	err = bitmap_parse(buf, len, cpumask_bits(mask), nr_cpumask_bits);
+	if (err)
+		goto out;
+
+	err = rps_cpumask_housekeeping(mask);
+	if (err)
+		goto out;
+
+	err = netdev_rx_queue_set_rps_mask(queue, mask);
+
+out:
 	free_cpumask_var(mask);
-	return len;
+	return err ? : len;
 }
 
 static ssize_t show_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue,