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macvlan: remove one synchronize_rcu() call 

When one macvlan device is dismantled, we can avoid one
synchronize_rcu() call done after deletion from hash list, since caller
will perform a synchronize_net() call after its ndo_stop() call.

Add a new netdev->dismantle field to signal this dismantle intent.

Reduces RTNL hold time.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
CC: Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-05-19 12:24:16 +00:00 committed by David S. Miller
parent 034cfe48d0
commit 449f454426
3 changed files with 9 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/net/macvlan.c
View File

@ -70,16 +70,17 @@ static void macvlan_hash_add(struct macvlan_dev *vlan)
hlist_add_head_rcu(&vlan->hlist, &port->vlan_hash[addr[5]]);
}
static void macvlan_hash_del(struct macvlan_dev *vlan)
static void macvlan_hash_del(struct macvlan_dev *vlan, bool sync)
{
hlist_del_rcu(&vlan->hlist);
synchronize_rcu();
if (sync)
synchronize_rcu();
}
static void macvlan_hash_change_addr(struct macvlan_dev *vlan,
const unsigned char *addr)
{
macvlan_hash_del(vlan);
macvlan_hash_del(vlan, true);
/* Now that we are unhashed it is safe to change the device
* address without confusing packet delivery.
*/
@ -345,7 +346,7 @@ static int macvlan_stop(struct net_device *dev)
dev_uc_del(lowerdev, dev->dev_addr);
hash_del:
macvlan_hash_del(vlan);
macvlan_hash_del(vlan, !dev->dismantle);
return 0;
}

4
include/linux/netdevice.h
View File

@ -1293,7 +1293,9 @@ struct net_device {
NETREG_UNREGISTERED, /* completed unregister todo */
NETREG_RELEASED, /* called free_netdev */
NETREG_DUMMY, /* dummy device for NAPI poll */
} reg_state:16;
} reg_state:8;
bool dismantle; /* device is going do be freed */
enum {
RTNL_LINK_INITIALIZED,

2
net/core/dev.c
View File

@ -5126,7 +5126,7 @@ static void rollback_registered_many(struct list_head *head)
list_del(&dev->unreg_list);
continue;
}
dev->dismantle = true;
BUG_ON(dev->reg_state != NETREG_REGISTERED);
}