netdev - Re: [PATCH net] udp: fix rx queue len reported by diag and proc interface

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Date:   Fri, 08 Jun 2018 19:56:12 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     pabeni@...hat.com
Cc:     netdev@...r.kernel.org, edumazet@...gle.com,
        trevor.francis@...abs.com
Subject: Re: [PATCH net] udp: fix rx queue len reported by diag and proc
 interface

From: Paolo Abeni <pabeni@...hat.com>
Date: Fri,  8 Jun 2018 11:35:40 +0200

> After commit 6b229cf77d68 ("udp: add batching to udp_rmem_release()")
> the sk_rmem_alloc field does not measure exactly anymore the
> receive queue length, because we batch the rmem release. The issue
> is really apparent only after commit 0d4a6608f68c ("udp: do rmem bulk
> free even if the rx sk queue is empty"): the user space can easily
> check for an empty socket with not-0 queue length reported by the 'ss'
> tool or the procfs interface.
> 
> We need to use a custom UDP helper to report the correct queue length,
> taking into account the forward allocation deficit.
> 
> Reported-by: trevor.francis@...abs.com
> Fixes: 6b229cf77d68 ("UDP: add batching to udp_rmem_release()")
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>

Applied and queued up for -stable, thanks.