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tipc: move the delivery of named messages out of nametbl lock

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Commit a89778d8ba ("tipc: add support
for link state subscriptions") introduced below possible deadlock
scenario:

       CPU0                          CPU1
T0:   tipc_publish()                 link_timeout()
T1:   tipc_nametbl_publish()         [grab node lock]*
T2:   [grab nametbl write lock]*     link_state_event()
T3:   named_cluster_distribute()     link_activate()
T4:   [grab node lock]*              tipc_node_link_up()
T5:                                  tipc_nametbl_publish()
T6:                                  [grab nametble write lock]*

The opposite order of holding nametbl write lock and node lock on
above two different paths may result in a deadlock. If we move the
the delivery of named messages via link out of name nametbl lock,
the reverse order of holding locks will be eliminated, as a result,
the deadlock will be killed as well.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ying Xue
2014-04-28 18:00:10 +08:00
committed by David S. Miller
parent d7bb74c38c
commit eab8c04573
3 changed files with 22 additions and 13 deletions
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18
net/tipc/name_distr.c
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@@ -127,7 +127,7 @@ static struct sk_buff *named_prepare_buf(u32 type, u32 size, u32 dest)
return buf;
}
static void named_cluster_distribute(struct sk_buff *buf)
void named_cluster_distribute(struct sk_buff *buf)
{
struct sk_buff *buf_copy;
struct tipc_node *n_ptr;
@@ -156,7 +156,7 @@ static void named_cluster_distribute(struct sk_buff *buf)
/**
* tipc_named_publish - tell other nodes about a new publication by this node
*/
void tipc_named_publish(struct publication *publ)
struct sk_buff *tipc_named_publish(struct publication *publ)
{
struct sk_buff *buf;
struct distr_item *item;
@@ -165,23 +165,23 @@ void tipc_named_publish(struct publication *publ)
publ_lists[publ->scope]->size++;
if (publ->scope == TIPC_NODE_SCOPE)
return;
return NULL;
buf = named_prepare_buf(PUBLICATION, ITEM_SIZE, 0);
if (!buf) {
pr_warn("Publication distribution failure\n");
return;
return NULL;
}
item = (struct distr_item *)msg_data(buf_msg(buf));
publ_to_item(item, publ);
named_cluster_distribute(buf);
return buf;
}
/**
* tipc_named_withdraw - tell other nodes about a withdrawn publication by this node
*/
void tipc_named_withdraw(struct publication *publ)
struct sk_buff *tipc_named_withdraw(struct publication *publ)
{
struct sk_buff *buf;
struct distr_item *item;
@@ -190,17 +190,17 @@ void tipc_named_withdraw(struct publication *publ)
publ_lists[publ->scope]->size--;
if (publ->scope == TIPC_NODE_SCOPE)
return;
return NULL;
buf = named_prepare_buf(WITHDRAWAL, ITEM_SIZE, 0);
if (!buf) {
pr_warn("Withdrawal distribution failure\n");
return;
return NULL;
}
item = (struct distr_item *)msg_data(buf_msg(buf));
publ_to_item(item, publ);
named_cluster_distribute(buf);
return buf;
}
/*