inet: cleanup of local_port_range

I noticed sysctl_local_port_range[] and its associated seqlock
sysctl_local_port_range_lock were on separate cache lines.
Moreover, sysctl_local_port_range[] was close to unrelated
variables, highly modified, leading to cache misses.

Moving these two variables in a structure can help data
locality and moving this structure to read_mostly section
helps sharing of this data among cpus.

Cleanup of extern declarations (moved in include file where
they belong), and use of inet_get_local_port_range()
accessor instead of direct access to ports values.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 23 insertions, 20 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index d678ea3d474a..1cbccaf0de3f 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -178,6 +178,10 @@ extern unsigned long snmp_fold_field(void *mib[], int offt);
 extern int snmp_mib_init(void *ptr[2], size_t mibsize);
 extern void snmp_mib_free(void *ptr[2]);
 
+extern struct local_ports {
+        seqlock_t       lock;
+        int             range[2];
+} sysctl_local_ports;
 extern void inet_get_local_port_range(int *low, int *high);
 
 extern int sysctl_ip_default_ttl;
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 21fcc5a9045f..bd1278a2d828 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -30,20 +30,22 @@ EXPORT_SYMBOL(inet_csk_timer_bug_msg);
 #endif
 
 /*
- * This array holds the first and last local port number.
+ * This struct holds the first and last local port number.
  */
-int sysctl_local_port_range[2] = { 32768, 61000 };
-DEFINE_SEQLOCK(sysctl_port_range_lock);
+struct local_ports sysctl_local_ports __read_mostly = {
+        .lock = SEQLOCK_UNLOCKED,
+        .range = { 32768, 61000 },
+};
 
 void inet_get_local_port_range(int *low, int *high)
 {
         unsigned seq;
         do {
-                seq = read_seqbegin(&sysctl_port_range_lock);
+                seq = read_seqbegin(&sysctl_local_ports.lock);
 
-                *low = sysctl_local_port_range[0];
-                *high = sysctl_local_port_range[1];
-        } while (read_seqretry(&sysctl_port_range_lock, seq));
+                *low = sysctl_local_ports.range[0];
+                *high = sysctl_local_ports.range[1];
+        } while (read_seqretry(&sysctl_local_ports.lock, seq));
 }
 EXPORT_SYMBOL(inet_get_local_port_range);
 
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index e0689fd7b798..276d047fb85a 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -26,16 +26,13 @@ static int tcp_retr1_max = 255;
 static int ip_local_port_range_min[] = { 1, 1 };
 static int ip_local_port_range_max[] = { 65535, 65535 };
 
-extern seqlock_t sysctl_port_range_lock;
-extern int sysctl_local_port_range[2];
-
 /* Update system visible IP port range */
 static void set_local_port_range(int range[2])
 {
-        write_seqlock(&sysctl_port_range_lock);
-        sysctl_local_port_range[0] = range[0];
-        sysctl_local_port_range[1] = range[1];
-        write_sequnlock(&sysctl_port_range_lock);
+        write_seqlock(&sysctl_local_ports.lock);
+        sysctl_local_ports.range[0] = range[0];
+        sysctl_local_ports.range[1] = range[1];
+        write_sequnlock(&sysctl_local_ports.lock);
 }
 
 /* Validate changes from /proc interface. */
@@ -44,8 +41,7 @@ static int ipv4_local_port_range(ctl_table *table, int write, struct file *filp,
                                  size_t *lenp, loff_t *ppos)
 {
         int ret;
-        int range[2] = { sysctl_local_port_range[0],
-                         sysctl_local_port_range[1] };
+        int range[2];
         ctl_table tmp = {
                 .data = &range,
                 .maxlen = sizeof(range),
@@ -54,6 +50,7 @@ static int ipv4_local_port_range(ctl_table *table, int write, struct file *filp,
                 .extra2 = &ip_local_port_range_max,
         };
 
+        inet_get_local_port_range(range, range + 1);
         ret = proc_dointvec_minmax(&tmp, write, filp, buffer, lenp, ppos);
 
         if (write && ret == 0) {
@@ -73,8 +70,7 @@ static int ipv4_sysctl_local_port_range(ctl_table *table, int __user *name,
                                         void __user *newval, size_t newlen)
 {
         int ret;
-        int range[2] = { sysctl_local_port_range[0],
-                         sysctl_local_port_range[1] };
+        int range[2];
         ctl_table tmp = {
                 .data = &range,
                 .maxlen = sizeof(range),
@@ -83,6 +79,7 @@ static int ipv4_sysctl_local_port_range(ctl_table *table, int __user *name,
                 .extra2 = &ip_local_port_range_max,
         };
 
+        inet_get_local_port_range(range, range + 1);
         ret = sysctl_intvec(&tmp, name, nlen, oldval, oldlenp, newval, newlen);
         if (ret == 0 && newval && newlen) {
                 if (range[1] < range[0])
@@ -396,8 +393,8 @@ static struct ctl_table ipv4_table[] = {
         {
                 .ctl_name       = NET_IPV4_LOCAL_PORT_RANGE,
                 .procname       = "ip_local_port_range",
-                .data           = &sysctl_local_port_range,
-                .maxlen         = sizeof(sysctl_local_port_range),
+                .data           = &sysctl_local_ports.range,
+                .maxlen         = sizeof(sysctl_local_ports.range),
                 .mode           = 0644,
                 .proc_handler   = &ipv4_local_port_range,
                 .strategy       = &ipv4_sysctl_local_port_range,