tipc: convert bearer_list to RCU list

Convert bearer_list to RCU list. It's protected by RTNL lock on
update side, and RCU read lock is applied to read side.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Tested-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 18 insertions, 13 deletions

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 95ab5ef92920..223a19929024 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -659,6 +659,7 @@ void tipc_bcbearer_sort(void)
 {
         struct tipc_bcbearer_pair *bp_temp = bcbearer->bpairs_temp;
         struct tipc_bcbearer_pair *bp_curr;
+        struct tipc_bearer *b;
         int b_index;
         int pri;
 
@@ -667,8 +668,9 @@ void tipc_bcbearer_sort(void)
         /* Group bearers by priority (can assume max of two per priority) */
         memset(bp_temp, 0, sizeof(bcbearer->bpairs_temp));
 
+        rcu_read_lock();
         for (b_index = 0; b_index < MAX_BEARERS; b_index++) {
-                struct tipc_bearer *b = bearer_list[b_index];
+                b = rcu_dereference_rtnl(bearer_list[b_index]);
                 if (!b || !b->nodes.count)
                         continue;
 
@@ -677,6 +679,7 @@ void tipc_bcbearer_sort(void)
                 else
                         bp_temp[b->priority].secondary = b;
         }
+        rcu_read_unlock();
 
         /* Create array of bearer pairs for broadcasting */
         bp_curr = bcbearer->bpairs;
@@ -784,7 +787,7 @@ void tipc_bclink_init(void)
         bcl->max_pkt = MAX_PKT_DEFAULT_MCAST;
         tipc_link_set_queue_limits(bcl, BCLINK_WIN_DEFAULT);
         bcl->b_ptr = &bcbearer->bearer;
-        bearer_list[BCBEARER] = &bcbearer->bearer;
+        rcu_assign_pointer(bearer_list[MAX_BEARERS], &bcbearer->bearer);
         bcl->state = WORKING_WORKING;
         strlcpy(bcl->name, tipc_bclink_name, TIPC_MAX_LINK_NAME);
 }
@@ -795,7 +798,7 @@ void tipc_bclink_stop(void)
         tipc_link_purge_queues(bcl);
         spin_unlock_bh(&bc_lock);
 
-        bearer_list[BCBEARER] = NULL;
+        RCU_INIT_POINTER(bearer_list[BCBEARER], NULL);
         memset(bclink, 0, sizeof(*bclink));
         memset(bcbearer, 0, sizeof(*bcbearer));
 }
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index dfb4c7fe4865..65b17639e43d 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -49,7 +49,7 @@ static struct tipc_media * const media_info_array[] = {
         NULL
 };
 
-struct tipc_bearer *bearer_list[MAX_BEARERS + 1];
+struct tipc_bearer __rcu *bearer_list[MAX_BEARERS + 1];
 
 static void bearer_disable(struct tipc_bearer *b_ptr, bool shutting_down);
 
@@ -178,7 +178,7 @@ struct tipc_bearer *tipc_bearer_find(const char *name)
         u32 i;
 
         for (i = 0; i < MAX_BEARERS; i++) {
-                b_ptr = bearer_list[i];
+                b_ptr = rtnl_dereference(bearer_list[i]);
                 if (b_ptr && (!strcmp(b_ptr->name, name)))
                         return b_ptr;
         }
@@ -201,7 +201,7 @@ struct sk_buff *tipc_bearer_get_names(void)
         read_lock_bh(&tipc_net_lock);
         for (i = 0; media_info_array[i] != NULL; i++) {
                 for (j = 0; j < MAX_BEARERS; j++) {
-                        b = bearer_list[j];
+                        b = rtnl_dereference(bearer_list[j]);
                         if (!b)
                                 continue;
                         if (b->media == media_info_array[i]) {
@@ -287,7 +287,7 @@ restart:
         bearer_id = MAX_BEARERS;
         with_this_prio = 1;
         for (i = MAX_BEARERS; i-- != 0; ) {
-                b_ptr = bearer_list[i];
+                b_ptr = rtnl_dereference(bearer_list[i]);
                 if (!b_ptr) {
                         bearer_id = i;
                         continue;
@@ -344,7 +344,7 @@ restart:
                 goto exit;
         }
 
-        bearer_list[bearer_id] = b_ptr;
+        rcu_assign_pointer(bearer_list[bearer_id], b_ptr);
 
         pr_info("Enabled bearer <%s>, discovery domain %s, priority %u\n",
                 name,
@@ -385,12 +385,12 @@ static void bearer_disable(struct tipc_bearer *b_ptr, bool shutting_down)
                 tipc_disc_delete(b_ptr->link_req);
 
         for (i = 0; i < MAX_BEARERS; i++) {
-                if (b_ptr == bearer_list[i]) {
-                        bearer_list[i] = NULL;
+                if (b_ptr == rtnl_dereference(bearer_list[i])) {
+                        RCU_INIT_POINTER(bearer_list[i], NULL);
                         break;
                 }
         }
-        kfree(b_ptr);
+        kfree_rcu(b_ptr, rcu);
 }
 
 int tipc_disable_bearer(const char *name)
@@ -628,7 +628,7 @@ void tipc_bearer_stop(void)
         u32 i;
 
         for (i = 0; i < MAX_BEARERS; i++) {
-                b_ptr = bearer_list[i];
+                b_ptr = rtnl_dereference(bearer_list[i]);
                 if (b_ptr) {
                         bearer_disable(b_ptr, true);
                         bearer_list[i] = NULL;
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index ba48145e871d..b67b7ea4cc36 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -113,6 +113,7 @@ struct tipc_media {
  * @name: bearer name (format = media:interface)
  * @media: ptr to media structure associated with bearer
  * @bcast_addr: media address used in broadcasting
+ * @rcu: rcu struct for tipc_bearer
  * @priority: default link priority for bearer
  * @window: default window size for bearer
  * @tolerance: default link tolerance for bearer
@@ -133,6 +134,7 @@ struct tipc_bearer {
         char name[TIPC_MAX_BEARER_NAME];
         struct tipc_media *media;
         struct tipc_media_addr bcast_addr;
+        struct rcu_head rcu;
         u32 priority;
         u32 window;
         u32 tolerance;
@@ -150,7 +152,7 @@ struct tipc_bearer_names {
 
 struct tipc_link;
 
-extern struct tipc_bearer *bearer_list[];
+extern struct tipc_bearer __rcu *bearer_list[];
 
 /*
  * TIPC routines available to supported media types