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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: 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>
This commit is contained in:
Ying Xue 2014-04-21 10:55:47 +08:00 committed by David S. Miller
parent 7a2f7d18e7
commit 2231c5af45
2 changed files with 11 additions and 4 deletions
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13
net/tipc/bearer.c
View File

@ -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)

2
net/tipc/bearer.h
View File

@ -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];