netdev - Re: [PATCH] af_packet: TPACKET_V3: fix fill status rwlock imbalance

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Message-Id: <20200813.153842.596513779122352190.davem@davemloft.net>
Date:   Thu, 13 Aug 2020 15:38:42 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     john.ogness@...utronix.de
Cc:     kuba@...nel.org, bigeasy@...utronix.de, tglx@...utronix.de,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] af_packet: TPACKET_V3: fix fill status rwlock imbalance

From: John Ogness <john.ogness@...utronix.de>
Date: Thu, 13 Aug 2020 21:45:25 +0206

> After @blk_fill_in_prog_lock is acquired there is an early out vnet
> situation that can occur. In that case, the rwlock needs to be
> released.
> 
> Also, since @blk_fill_in_prog_lock is only acquired when @tp_version
> is exactly TPACKET_V3, only release it on that exact condition as
> well.
> 
> And finally, add sparse annotation so that it is clearer that
> prb_fill_curr_block() and prb_clear_blk_fill_status() are acquiring
> and releasing @blk_fill_in_prog_lock, respectively. sparse is still
> unable to understand the balance, but the warnings are now on a
> higher level that make more sense.
> 
> Fixes: 632ca50f2cbd ("af_packet: TPACKET_V3: replace busy-wait loop")
> Signed-off-by: John Ogness <john.ogness@...utronix.de>
> Reported-by: kernel test robot <lkp@...el.com>

Good catch, applied.