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Date: Wed, 9 Jul 2025 19:15:02 +0100
From: Simon Horman <horms@kernel.org>
To: Yun Lu <luyun_611@163.com>
Cc: willemdebruijn.kernel@gmail.com, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] af_packet: fix the SO_SNDTIMEO constraint not
 effective on tpacked_snd()
Message-ID: <20250709181502.GI721198@horms.kernel.org>
References: <20250709095653.62469-1-luyun_611@163.com>
 <20250709095653.62469-2-luyun_611@163.com>
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In-Reply-To: <20250709095653.62469-2-luyun_611@163.com>

On Wed, Jul 09, 2025 at 05:56:52PM +0800, Yun Lu wrote:
> From: Yun Lu <luyun@kylinos.cn>
> 
> Due to the changes in commit 581073f626e3 ("af_packet: do not call
> packet_read_pending() from tpacket_destruct_skb()"), every time
> tpacket_destruct_skb() is executed, the skb_completion is marked as
> completed. When wait_for_completion_interruptible_timeout() returns
> completed, the pending_refcnt has not yet been reduced to zero.
> Therefore, when ph is NULL, the wait function may need to be called
> multiple times untill packet_read_pending() finally returns zero.

nit: until

> 
> We should call sock_sndtimeo() only once, otherwise the SO_SNDTIMEO
> constraint could be way off.
> 
> Fixes: 581073f626e3 ("af_packet: do not call packet_read_pending() from tpacket_destruct_skb()")
> Cc: stable@kernel.org
> Suggested-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Yun Lu <luyun@kylinos.cn>

...