[net] bonding: fix panic on non-ARPHRD_ETHER enslave failure

Since commit 7d5cd2ce529b, when bond_enslave fails on devices that
are not ARPHRD_ETHER, if needed, it resets the bonding device back to
ARPHRD_ETHER by calling ether_setup.

	Unfortunately, ether_setup clobbers dev->flags, clearing IFF_UP
if the bond device is up, leaving it in a quasi-down state without
having actually gone through dev_close.  For bonding, if any periodic
work queue items are active (miimon, arp_interval, etc), those will
remain running, as they are stopped by bond_close.  At this point, if
the bonding module is unloaded or the bond is deleted, the system will
panic when the work function is called.

	This panic is resolved by calling dev_close on the bond itself
prior to calling ether_setup.

Cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Fixes: 7d5cd2ce5292 ("bonding: correctly handle bonding type change on enslave failure")

---
 drivers/net/bonding/bond_main.c | 1 +
 1 file changed, 1 insertion(+)

On 11/07/2015 02:23 AM, Jay Vosburgh wrote:
> 	Since commit 7d5cd2ce529b, when bond_enslave fails on devices that
> are not ARPHRD_ETHER, if needed, it resets the bonding device back to
> ARPHRD_ETHER by calling ether_setup.
> 
> 	Unfortunately, ether_setup clobbers dev->flags, clearing IFF_UP
> if the bond device is up, leaving it in a quasi-down state without
> having actually gone through dev_close.  For bonding, if any periodic
> work queue items are active (miimon, arp_interval, etc), those will
> remain running, as they are stopped by bond_close.  At this point, if
> the bonding module is unloaded or the bond is deleted, the system will
> panic when the work function is called.
> 
> 	This panic is resolved by calling dev_close on the bond itself
> prior to calling ether_setup.
> 
> Cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
> Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
> Fixes: 7d5cd2ce5292 ("bonding: correctly handle bonding type change on enslave failure")
> 
> ---
>  drivers/net/bonding/bond_main.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index b4351ca..9e0f8a7 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1749,6 +1749,7 @@ err_undo_flags:
>  					    slave_dev->dev_addr))
>  			eth_hw_addr_random(bond_dev);
>  		if (bond_dev->type != ARPHRD_ETHER) {
> +			dev_close(bond_dev);
>  			ether_setup(bond_dev);
>  			bond_dev->flags |= IFF_MASTER;
>  			bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING;
> 

Oh, I've missed it. Very good catch!

Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

Thanks,
 Nik
 
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From: Jay Vosburgh <jay.vosburgh@canonical.com>
Date: Fri, 06 Nov 2015 17:23:23 -0800

> 
> 	Since commit 7d5cd2ce529b, when bond_enslave fails on devices that
> are not ARPHRD_ETHER, if needed, it resets the bonding device back to
> ARPHRD_ETHER by calling ether_setup.
> 
> 	Unfortunately, ether_setup clobbers dev->flags, clearing IFF_UP
> if the bond device is up, leaving it in a quasi-down state without
> having actually gone through dev_close.  For bonding, if any periodic
> work queue items are active (miimon, arp_interval, etc), those will
> remain running, as they are stopped by bond_close.  At this point, if
> the bonding module is unloaded or the bond is deleted, the system will
> panic when the work function is called.
> 
> 	This panic is resolved by calling dev_close on the bond itself
> prior to calling ether_setup.
> 
> Cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
> Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
> Fixes: 7d5cd2ce5292 ("bonding: correctly handle bonding type change on enslave failure")

Applied and queued up for -stable, thanks.
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