Commit eab8c045 authored by Ying Xue's avatar Ying Xue Committed by David S. Miller
Browse files

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



Commit a89778d8 ("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: default avatarYing Xue <ying.xue@windriver.com>
Reviewed-by: default avatarErik Hugne <erik.hugne@ericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d7bb74c3

net/tipc/name_distr.c

+9 −9
Original line number Diff line number Diff line
@@ -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 * tipc_named_withdraw - tell other nodes about a withdrawn publication by this node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;

}



/*

net/tipc/name_distr.h

+3 −2
Original line number Diff line number Diff line
@@ -39,8 +39,9 @@ 


#include "name_table.h"



void tipc_named_publish(struct publication *publ);

void tipc_named_withdraw(struct publication *publ);

struct sk_buff *tipc_named_publish(struct publication *publ);

struct sk_buff *tipc_named_withdraw(struct publication *publ);

void named_cluster_distribute(struct sk_buff *buf);

void tipc_named_node_up(unsigned long node);

void tipc_named_rcv(struct sk_buff *buf);

void tipc_named_reinit(void);

net/tipc/name_table.c

+10 −2
Original line number Diff line number Diff line
@@ -664,6 +664,7 @@ struct publication *tipc_nametbl_publish(u32 type, u32 lower, u32 upper, 
					 u32 scope, u32 port_ref, u32 key)

{

	struct publication *publ;

	struct sk_buff *buf = NULL;



	if (table.local_publ_count >= TIPC_MAX_PUBLICATIONS) {

		pr_warn("Publication failed, local publication limit reached (%u)\n",
@@ -676,9 +677,12 @@ struct publication *tipc_nametbl_publish(u32 type, u32 lower, u32 upper, 
				   tipc_own_addr, port_ref, key);

	if (likely(publ)) {

		table.local_publ_count++;

		tipc_named_publish(publ);

		buf = tipc_named_publish(publ);

	}

	write_unlock_bh(&tipc_nametbl_lock);



	if (buf)

		named_cluster_distribute(buf);

	return publ;

}
@@ -688,15 +692,19 @@ struct publication *tipc_nametbl_publish(u32 type, u32 lower, u32 upper, 
int tipc_nametbl_withdraw(u32 type, u32 lower, u32 ref, u32 key)

{

	struct publication *publ;

	struct sk_buff *buf;



	write_lock_bh(&tipc_nametbl_lock);

	publ = tipc_nametbl_remove_publ(type, lower, tipc_own_addr, ref, key);

	if (likely(publ)) {

		table.local_publ_count--;

		tipc_named_withdraw(publ);

		buf = tipc_named_withdraw(publ);

		write_unlock_bh(&tipc_nametbl_lock);

		list_del_init(&publ->pport_list);

		kfree(publ);



		if (buf)

			named_cluster_distribute(buf);

		return 1;

	}

	write_unlock_bh(&tipc_nametbl_lock);

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