tipc: convert tipc reference table to use generic rhashtable

As tipc reference table is statically allocated, its memory size
requested on stack initialization stage is quite big even if the
maximum port number is just restricted to 8191 currently, however,
the number already becomes insufficient in practice. But if the
maximum ports is allowed to its theory value - 2^32, its consumed
memory size will reach a ridiculously unacceptable value. Apart from
this, heavy tipc users spend a considerable amount of time in
tipc_sk_get() due to the read-lock on ref_table_lock.

If tipc reference table is converted with generic rhashtable, above
mentioned both disadvantages would be resolved respectively: making
use of the new resizable hash table can avoid locking on the lookup;
smaller memory size is required at initial stage, for example, 256
hash bucket slots are requested at the beginning phase instead of
allocating the entire 8191 slots in old mode. The hash table will
grow if entries exceeds 75% of table size up to a total table size
of 1M, and it will automatically shrink if usage falls below 30%,
but the minimum table size is allowed down to 256.

Also converts ref_table_lock to a separate mutex to protect hash table
mutations on write side. Lastly defers the release of the socket
reference using call_rcu() to allow using an RCU read-side protected
call to rhashtable_lookup().

Signed-off-by: Ying Xue <[email protected]>
Acked-by: Jon Maloy <[email protected]>
Acked-by: Erik Hugne <[email protected]>
Cc: Thomas Graf <[email protected]>
Acked-by: Thomas Graf <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: ying-xue

net/tipc/Kconfig

@@ -20,18 +20,6 @@ menuconfig TIPC
 
 	  If in doubt, say N.
 
-config TIPC_PORTS
-	int "Maximum number of ports in a node"
-	depends on TIPC
-	range 127 65535
-	default "8191"
-	help
-	  Specifies how many ports can be supported by a node.
-	  Can range from 127 to 65535 ports; default is 8191.
-
-	  Setting this to a smaller value saves some memory,
-	  setting it to higher allows for more ports.
-
 config TIPC_MEDIA_IB
 	bool "InfiniBand media type support"
 	depends on TIPC && INFINIBAND_IPOIB

net/tipc/config.c

@@ -183,22 +183,6 @@ static struct sk_buff *cfg_set_own_addr(void)
 	return tipc_cfg_reply_error_string("cannot change to network mode");
 }
 
-static struct sk_buff *cfg_set_max_ports(void)
-{
-	u32 value;
-
-	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
-		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
-	value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
-	if (value == tipc_max_ports)
-		return tipc_cfg_reply_none();
-	if (value < 127 || value > 65535)
-		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
-						   " (max ports must be 127-65535)");
-	return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
-		" (cannot change max ports while TIPC is active)");
-}
-
 static struct sk_buff *cfg_set_netid(void)
 {
 	u32 value;
@@ -285,15 +269,9 @@ struct sk_buff *tipc_cfg_do_cmd(u32 orig_node, u16 cmd, const void *request_area
 	case TIPC_CMD_SET_NODE_ADDR:
 		rep_tlv_buf = cfg_set_own_addr();
 		break;
-	case TIPC_CMD_SET_MAX_PORTS:
-		rep_tlv_buf = cfg_set_max_ports();
-		break;
 	case TIPC_CMD_SET_NETID:
 		rep_tlv_buf = cfg_set_netid();
 		break;
-	case TIPC_CMD_GET_MAX_PORTS:
-		rep_tlv_buf = tipc_cfg_reply_unsigned(tipc_max_ports);
-		break;
 	case TIPC_CMD_GET_NETID:
 		rep_tlv_buf = tipc_cfg_reply_unsigned(tipc_net_id);
 		break;
@@ -317,6 +295,8 @@ struct sk_buff *tipc_cfg_do_cmd(u32 orig_node, u16 cmd, const void *request_area
 	case TIPC_CMD_SET_REMOTE_MNG:
 	case TIPC_CMD_GET_REMOTE_MNG:
 	case TIPC_CMD_DUMP_LOG:
+	case TIPC_CMD_SET_MAX_PORTS:
+	case TIPC_CMD_GET_MAX_PORTS:
 		rep_tlv_buf = tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
 							  " (obsolete command)");
 		break;

net/tipc/core.c

@@ -34,6 +34,8 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include "core.h"
 #include "name_table.h"
 #include "subscr.h"
@@ -47,7 +49,6 @@ int tipc_random __read_mostly;
 
 /* configurable TIPC parameters */
 u32 tipc_own_addr __read_mostly;
-int tipc_max_ports __read_mostly;
 int tipc_net_id __read_mostly;
 int sysctl_tipc_rmem[3] __read_mostly;	/* min/default/max */
 
@@ -84,9 +85,9 @@ static void tipc_core_stop(void)
 	tipc_netlink_stop();
 	tipc_subscr_stop();
 	tipc_nametbl_stop();
-	tipc_sk_ref_table_stop();
 	tipc_socket_stop();
 	tipc_unregister_sysctl();
+	tipc_sk_rht_destroy();
 }
 
 /**
@@ -98,7 +99,7 @@ static int tipc_core_start(void)
 
 	get_random_bytes(&tipc_random, sizeof(tipc_random));
 
-	err = tipc_sk_ref_table_init(tipc_max_ports, tipc_random);
+	err = tipc_sk_rht_init();
 	if (err)
 		goto out_reftbl;
 
@@ -138,7 +139,7 @@ static int tipc_core_start(void)
 out_netlink:
 	tipc_nametbl_stop();
 out_nametbl:
-	tipc_sk_ref_table_stop();
+	tipc_sk_rht_destroy();
 out_reftbl:
 	return err;
 }
@@ -150,7 +151,6 @@ static int __init tipc_init(void)
 	pr_info("Activated (version " TIPC_MOD_VER ")\n");
 
 	tipc_own_addr = 0;
-	tipc_max_ports = CONFIG_TIPC_PORTS;
 	tipc_net_id = 4711;
 
 	sysctl_tipc_rmem[0] = TIPC_CONN_OVERLOAD_LIMIT >> 4 <<

net/tipc/core.h

@@ -37,8 +37,6 @@
 #ifndef _TIPC_CORE_H
 #define _TIPC_CORE_H
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
 #include <linux/tipc.h>
 #include <linux/tipc_config.h>
 #include <linux/tipc_netlink.h>
@@ -79,7 +77,6 @@ int tipc_snprintf(char *buf, int len, const char *fmt, ...);
  * Global configuration variables
  */
 extern u32 tipc_own_addr __read_mostly;
-extern int tipc_max_ports __read_mostly;
 extern int tipc_net_id __read_mostly;
 extern int sysctl_tipc_rmem[3] __read_mostly;
 extern int sysctl_tipc_named_timeout __read_mostly;