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net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()

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Le dimanche 05 décembre 2010 à 09:19 +0100, Eric Dumazet a écrit :

> Hmm..
>
> If somebody can explain why RTNL is held in arp_ioctl() (and therefore
> in arp_req_delete()), we might first remove RTNL use in arp_ioctl() so
> that your patch can be applied.
>
> Right now it is not good, because RTNL wont be necessarly held when you
> are going to call arp_invalidate() ?

While doing this analysis, I found a refcount bug in llc, I'll send a
patch for net-2.6

Meanwhile, here is the patch for net-next-2.6

Your patch then can be applied after mine.

Thanks

[PATCH] net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()

dev_getbyhwaddr() was called under RTNL.

Rename it to dev_getbyhwaddr_rcu() and change all its caller to now use
RCU locking instead of RTNL.

Change arp_ioctl() to use RCU instead of RTNL locking.

Note: this fix a dev refcount bug in llc

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2010-12-05 01:23:53 +00:00
committed by David S. Miller
parent a2d4b65d47
commit 941666c2e3
5 changed files with 27 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
net/core/dev.c
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@@ -743,34 +743,31 @@ struct net_device *dev_get_by_index(struct net *net, int ifindex)
EXPORT_SYMBOL(dev_get_by_index);
/**
* dev_getbyhwaddr - find a device by its hardware address
* dev_getbyhwaddr_rcu - find a device by its hardware address
* @net: the applicable net namespace
* @type: media type of device
* @ha: hardware address
*
* Search for an interface by MAC address. Returns NULL if the device
* is not found or a pointer to the device. The caller must hold the
* rtnl semaphore. The returned device has not had its ref count increased
* is not found or a pointer to the device. The caller must hold RCU
* The returned device has not had its ref count increased
* and the caller must therefore be careful about locking
*
* BUGS:
* If the API was consistent this would be __dev_get_by_hwaddr
*/
struct net_device *dev_getbyhwaddr(struct net *net, unsigned short type, char *ha)
struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
const char *ha)
{
struct net_device *dev;
ASSERT_RTNL();
for_each_netdev(net, dev)
for_each_netdev_rcu(net, dev)
if (dev->type == type &&
!memcmp(dev->dev_addr, ha, dev->addr_len))
return dev;
return NULL;
}
EXPORT_SYMBOL(dev_getbyhwaddr);
EXPORT_SYMBOL(dev_getbyhwaddr_rcu);
struct net_device *__dev_getfirstbyhwtype(struct net *net, unsigned short type)
{