[Lguest] [1/2] tun: Only free a netdev when all tun descriptors are closed

[Herbert Xu]

On Fri, Apr 24, 2009 at 10:55:49AM +0200, Christian Borntraeger wrote:
> Am Thursday 16 April 2009 13:08:18 schrieb Herbert Xu:
>
> > Here's the patch.  I'd appreciate if everyone can review it
> > and see if they can recreate the original race by
> > 
> > 1) Starting a process using tun and polls on it;
> > 2) Doing ip tun del tunXXX while the process is polling.
> > 
> > tun: Only free a netdev when all tun descriptors are closed
> > 
> > The commit c70f182940f988448f3c12a209d18b1edc276e33 ("tun: Fix
> > races between tun_net_close and free_netdev") fixed a race where
> > an asynchronous deletion of a tun device can hose a poll(2) on
> > a tun fd attached to that device.
> 
> Sorry for the late reply, but this patch creates another regression:
> Now TUNSETIFF returns EBUSY on a persistent tap device:
> 
> open("/dev/net/tun", O_RDWR) = 11
> ioctl(11, 0x400454ca, 0x3ffff8e2270) = -1 EBUSY (Device or resource busy)

The patch you qouted has been superceded by many versions :)

Can you please test the latest that's in davem's tree?

Thanks,
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