Re: [PATCH] [RFC] udp: ipv4: fix potential deadlock on sk_dst_lock

[Jiri Kosina]

On Mon, 16 Dec 2013, Eric Dumazet wrote:

> > Commit 975022310 ("udp: ipv4: must add synchronization in 
> > udp_sk_rx_dst_set()) caused sk_dst_lock to be obtained in udp4 receive 
> > path, which is happening in softirq context.
> > 
> > inet_bind() is taking sk_dst_lock (through sk_dst_reset()) without turning 
> > IRQs off, which results in the lockdep splat below.
> > 
> > Fix that by disabling IRQs while taking the lock in sk_dst_reset().
> 
> Thanks but I posted this fix instead :
> 
>  http://patchwork.ozlabs.org/patch/301382/

Right, I missed the incarnation in sk_dst_set(), so my patch is apparently 
incomplete anyway.

But using xchg also fixes the issue.

Thanks,

-- 
Jiri Kosina
SUSE Labs
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