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Commit 2231c5af authored by Ying Xue's avatar Ying Xue Committed by David S. Miller
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tipc: use RCU to protect media_ptr pointer 



Now the media_ptr pointer is protected with tipc_net_lock write lock
on write side; tipc_net_lock read lock is used to read side. As the
part of effort of eliminating tipc_net_lock, we decide to adjust the
locking policy of media_ptr pointer protection: on write side, RTNL
lock is use while on read side RCU read lock is applied.

Signed-off-by: default avatarYing Xue <ying.xue@windriver.com>
Reviewed-by: default avatarJon Maloy <jon.maloy@ericsson.com>
Reviewed-by: default avatarErik Hugne <erik.hugne@ericsson.com>
Tested-by: default avatarErik Hugne <erik.hugne@ericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7a2f7d18

net/tipc/bearer.c

+10 −3
Original line number Diff line number Diff line
@@ -458,7 +458,7 @@ int tipc_enable_l2_media(struct tipc_bearer *b) 
		return -ENODEV;



	/* Associate TIPC bearer with Ethernet bearer */

	b->media_ptr = dev;

	rcu_assign_pointer(b->media_ptr, dev);

	memset(b->bcast_addr.value, 0, sizeof(b->bcast_addr.value));

	memcpy(b->bcast_addr.value, dev->broadcast, b->media->hwaddr_len);

	b->bcast_addr.media_id = b->media->type_id;
@@ -477,7 +477,10 @@ int tipc_enable_l2_media(struct tipc_bearer *b) 
 */

void tipc_disable_l2_media(struct tipc_bearer *b)

{

	struct net_device *dev = (struct net_device *)b->media_ptr;

	struct net_device *dev;



	dev = (struct net_device *)rtnl_dereference(b->media_ptr);

	RCU_INIT_POINTER(b->media_ptr, NULL);

	RCU_INIT_POINTER(dev->tipc_ptr, NULL);

	dev_put(dev);

}
@@ -492,8 +495,12 @@ int tipc_l2_send_msg(struct sk_buff *buf, struct tipc_bearer *b, 
		     struct tipc_media_addr *dest)

{

	struct sk_buff *clone;

	struct net_device *dev;

	int delta;

	struct net_device *dev = (struct net_device *)b->media_ptr;



	dev = (struct net_device *)rcu_dereference_rtnl(b->media_ptr);

	if (!dev)

		return 0;



	clone = skb_clone(buf, GFP_ATOMIC);

	if (!clone)

net/tipc/bearer.h

+1 −1
Original line number Diff line number Diff line
@@ -128,7 +128,7 @@ struct tipc_media { 
 * care of initializing all other fields.

 */

struct tipc_bearer {

	void *media_ptr;			/* initalized by media */

	void __rcu *media_ptr;			/* initalized by media */

	u32 mtu;				/* initalized by media */

	struct tipc_media_addr addr;		/* initalized by media */

	char name[TIPC_MAX_BEARER_NAME];