net-sysctl: factor out cpumask parsing helper

Will be used by the following patch to avoid code
duplication. No functional changes intended.

The only difference is that now flow_limit_cpu_sysctl() will
always compute the flow limit mask on each read operation,
even when read() will not return any byte to user-space.

Note that the new helper is placed under a new #ifdef at
the file start to better fit the usage in the later patch

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index e7b98162c63218feec0eefbd1621c5e9df5f22e1..6935ecdc84b0d9d221af9bb624a5f3fac71fe808 100644 (file)
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -45,6 +45,33 @@ EXPORT_SYMBOL(sysctl_fb_tunnels_only_for_init_net);
 int sysctl_devconf_inherit_init_net __read_mostly;
 EXPORT_SYMBOL(sysctl_devconf_inherit_init_net);
 
+#if IS_ENABLED(CONFIG_NET_FLOW_LIMIT)
+static void dump_cpumask(void *buffer, size_t *lenp, loff_t *ppos,
+                        struct cpumask *mask)
+{
+       char kbuf[128];
+       int len;
+
+       if (*ppos || !*lenp) {
+               *lenp = 0;
+               return;
+       }
+
+       len = min(sizeof(kbuf) - 1, *lenp);
+       len = scnprintf(kbuf, len, "%*pb", cpumask_pr_args(mask));
+       if (!len) {
+               *lenp = 0;
+               return;
+       }
+
+       if (len < *lenp)
+               kbuf[len++] = '\n';
+       memcpy(buffer, kbuf, len);
+       *lenp = len;
+       *ppos += len;
+}
+#endif
+
 #ifdef CONFIG_RPS
 static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
                                void *buffer, size_t *lenp, loff_t *ppos)
@@ -155,13 +182,6 @@ static int flow_limit_cpu_sysctl(struct ctl_table *table, int write,
 write_unlock:
                mutex_unlock(&flow_limit_update_mutex);
        } else {
-               char kbuf[128];
-
-               if (*ppos || !*lenp) {
-                       *lenp = 0;
-                       goto done;
-               }
-
                cpumask_clear(mask);
                rcu_read_lock();
                for_each_possible_cpu(i) {
@@ -171,17 +191,7 @@ write_unlock:
                }
                rcu_read_unlock();
 
-               len = min(sizeof(kbuf) - 1, *lenp);
-               len = scnprintf(kbuf, len, "%*pb", cpumask_pr_args(mask));
-               if (!len) {
-                       *lenp = 0;
-                       goto done;
-               }
-               if (len < *lenp)
-                       kbuf[len++] = '\n';
-               memcpy(buffer, kbuf, len);
-               *lenp = len;
-               *ppos += len;
+               dump_cpumask(buffer, lenp, ppos, mask);
        }
 
 done: