Re: [GIT]: Networking

Ingo Molnar
2009-08-05T07:14:30Z

* Ingo Molnar <mingo@elte.hu> wrote:

> FYI, -tip testing found that these bits trigger a missing lockdep
> annotation warning:

it's apparently using an zero-initialized spinlock. This is a
side-effect of:

dev_unicast_init(dev);

in alloc_netdev_mq() making use of dev->addr_list_lock.

Wouldnt the patch below be the right fix? The device has just been
allocated freshly, it's not accessible anywhere yet so no locking is
needed at all - in fact it's wrong to lock it here (the lock isnt
initialized yet).

This bug was apparently introduced via:

| commit a6ac65db2329e7685299666f5f7b6093c7b0f3a0
| Author: Jiri Pirko <jpirko@redhat.com>
| Date: Thu Jul 30 01:06:12 2009 +0000
|
| net: restore the original spinlock to protect unicast list

it needlessly added new locking and apparently nobody ran this patch
with lockdep.

Ingo

Index: linux2/net/core/dev.c
===================================================================
--- linux2.orig/net/core/dev.c
+++ linux2/net/core/dev.c
@@ -4007,9 +4007,7 @@ static void dev_unicast_flush(struct net

static void dev_unicast_init(struct net_device *dev)
{
- netif_addr_lock_bh(dev);
__hw_addr_init(&dev->uc);
- netif_addr_unlock_bh(dev);
}