tipc: purge tipc_net_lock lock
Now tipc routing hierarchy comprises the structures 'node', 'link'and
'bearer'. The whole hierarchy is protected by a big read/write lock,
tipc_net_lock, to ensure that nothing is added or removed while code
is accessing any of these structures. Obviously the locking policy
makes node, link and bearer components closely bound together so that
their relationship becomes unnecessarily complex. In the worst case,
such locking policy not only has a negative influence on performance,
but also it's prone to lead to deadlock occasionally.
In order o decouple the complex relationship between bearer and node
as well as link, the locking policy is adjusted as follows:
- Bearer level
RTNL lock is used on update side, and RCU is used on read side.
Meanwhile, all bearer instances including broadcast bearer are
saved into bearer_list array.
- Node and link level
All node instances are saved into two tipc_node_list and node_htable
lists. The two lists are protected by node_list_lock on write side,
and they are guarded with RCU lock on read side. All members in node
structure including link instances are protected by node spin lock.
- The relationship between bearer and node
When link accesses bearer, it first needs to find the bearer with
its bearer identity from the bearer_list array. When bearer accesses
node, it can iterate the node_htable hash list with the node
address to find the corresponding node.
In the new locking policy, every component has its private locking
solution and the relationship between bearer and node is very simple,
that is, they can find each other with node address or bearer identity
from node_htable hash list or bearer_list array.
Until now above all changes have been done, so tipc_net_lock can be
removed safely.
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>
diff --git a/net/tipc/link.c b/net/tipc/link.c
index 229d478..c723ee9 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -835,7 +835,6 @@
struct tipc_node *n_ptr;
int res = -ELINKCONG;
- read_lock_bh(&tipc_net_lock);
n_ptr = tipc_node_find(dest);
if (n_ptr) {
tipc_node_lock(n_ptr);
@@ -848,7 +847,6 @@
} else {
kfree_skb(buf);
}
- read_unlock_bh(&tipc_net_lock);
return res;
}
@@ -912,7 +910,6 @@
if (list_empty(message_list))
return;
- read_lock_bh(&tipc_net_lock);
n_ptr = tipc_node_find(dest);
if (n_ptr) {
tipc_node_lock(n_ptr);
@@ -927,7 +924,6 @@
}
tipc_node_unlock(n_ptr);
}
- read_unlock_bh(&tipc_net_lock);
/* discard the messages if they couldn't be sent */
list_for_each_safe(buf, temp_buf, ((struct sk_buff *)message_list)) {
@@ -989,7 +985,6 @@
if (unlikely(res < 0))
return res;
- read_lock_bh(&tipc_net_lock);
node = tipc_node_find(destaddr);
if (likely(node)) {
tipc_node_lock(node);
@@ -1000,7 +995,6 @@
&sender->max_pkt);
exit:
tipc_node_unlock(node);
- read_unlock_bh(&tipc_net_lock);
return res;
}
@@ -1017,7 +1011,6 @@
*/
sender->max_pkt = l_ptr->max_pkt;
tipc_node_unlock(node);
- read_unlock_bh(&tipc_net_lock);
if ((msg_hdr_sz(hdr) + res) <= sender->max_pkt)
@@ -1028,7 +1021,6 @@
}
tipc_node_unlock(node);
}
- read_unlock_bh(&tipc_net_lock);
/* Couldn't find a link to the destination node */
kfree_skb(buf);
@@ -1273,12 +1265,9 @@
char addr_string[16];
u32 i;
- read_lock_bh(&tipc_net_lock);
n_ptr = tipc_node_find((u32)addr);
- if (!n_ptr) {
- read_unlock_bh(&tipc_net_lock);
+ if (!n_ptr)
return; /* node no longer exists */
- }
tipc_node_lock(n_ptr);
@@ -1293,7 +1282,6 @@
}
tipc_node_unlock(n_ptr);
- read_unlock_bh(&tipc_net_lock);
}
static void link_retransmit_failure(struct tipc_link *l_ptr,
@@ -1458,7 +1446,6 @@
*/
void tipc_rcv(struct sk_buff *head, struct tipc_bearer *b_ptr)
{
- read_lock_bh(&tipc_net_lock);
while (head) {
struct tipc_node *n_ptr;
struct tipc_link *l_ptr;
@@ -1646,7 +1633,6 @@
discard:
kfree_skb(buf);
}
- read_unlock_bh(&tipc_net_lock);
}
/**
@@ -2408,8 +2394,6 @@
/* tipc_link_find_owner - locate owner node of link by link's name
* @name: pointer to link name string
* @bearer_id: pointer to index in 'node->links' array where the link was found.
- * Caller must hold 'tipc_net_lock' to ensure node and bearer are not deleted;
- * this also prevents link deletion.
*
* Returns pointer to node owning the link, or 0 if no matching link is found.
*/
@@ -2471,7 +2455,7 @@
* @new_value: new value of link, bearer, or media setting
* @cmd: which link, bearer, or media attribute to set (TIPC_CMD_SET_LINK_*)
*
- * Caller must hold 'tipc_net_lock' to ensure link/bearer/media is not deleted.
+ * Caller must hold RTNL lock to ensure link/bearer/media is not deleted.
*
* Returns 0 if value updated and negative value on error.
*/
@@ -2577,9 +2561,7 @@
" (cannot change setting on broadcast link)");
}
- read_lock_bh(&tipc_net_lock);
res = link_cmd_set_value(args->name, new_value, cmd);
- read_unlock_bh(&tipc_net_lock);
if (res)
return tipc_cfg_reply_error_string("cannot change link setting");
@@ -2613,22 +2595,18 @@
return tipc_cfg_reply_error_string("link not found");
return tipc_cfg_reply_none();
}
- read_lock_bh(&tipc_net_lock);
node = tipc_link_find_owner(link_name, &bearer_id);
- if (!node) {
- read_unlock_bh(&tipc_net_lock);
+ if (!node)
return tipc_cfg_reply_error_string("link not found");
- }
+
tipc_node_lock(node);
l_ptr = node->links[bearer_id];
if (!l_ptr) {
tipc_node_unlock(node);
- read_unlock_bh(&tipc_net_lock);
return tipc_cfg_reply_error_string("link not found");
}
link_reset_statistics(l_ptr);
tipc_node_unlock(node);
- read_unlock_bh(&tipc_net_lock);
return tipc_cfg_reply_none();
}
@@ -2661,18 +2639,15 @@
if (!strcmp(name, tipc_bclink_name))
return tipc_bclink_stats(buf, buf_size);
- read_lock_bh(&tipc_net_lock);
node = tipc_link_find_owner(name, &bearer_id);
- if (!node) {
- read_unlock_bh(&tipc_net_lock);
+ if (!node)
return 0;
- }
+
tipc_node_lock(node);
l = node->links[bearer_id];
if (!l) {
tipc_node_unlock(node);
- read_unlock_bh(&tipc_net_lock);
return 0;
}
@@ -2738,7 +2713,6 @@
(s->accu_queue_sz / s->queue_sz_counts) : 0);
tipc_node_unlock(node);
- read_unlock_bh(&tipc_net_lock);
return ret;
}
@@ -2789,7 +2763,6 @@
if (dest == tipc_own_addr)
return MAX_MSG_SIZE;
- read_lock_bh(&tipc_net_lock);
n_ptr = tipc_node_find(dest);
if (n_ptr) {
tipc_node_lock(n_ptr);
@@ -2798,7 +2771,6 @@
res = l_ptr->max_pkt;
tipc_node_unlock(n_ptr);
}
- read_unlock_bh(&tipc_net_lock);
return res;
}