linux-kernel - Re: [PATCH net-next v2] 6pack: drop redundant locking and refcounting

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Message-ID: <aNTdLU7amoq0bCnS@stanley.mountain>
Date: Thu, 25 Sep 2025 09:11:57 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Qingfang Deng <dqfext@...il.com>
Cc: Andreas Koensgen <ajk@...nets.uni-bremen.de>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	linux-hams@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	syzbot+5fd749c74105b0e1b302@...kaller.appspotmail.com
Subject: Re: [PATCH net-next v2] 6pack: drop redundant locking and refcounting

On Thu, Sep 25, 2025 at 01:10:59PM +0800, Qingfang Deng wrote:
> The TTY layer already serializes line discipline operations with
> tty->ldisc_sem, so the extra disc_data_lock and refcnt in 6pack
> are unnecessary.
> 
> Removing them simplifies the code and also resolves a lockdep warning
> reported by syzbot. The warning did not indicate a real deadlock, since
> the write-side lock was only taken in process context with hardirqs
> disabled.
> 
> Reported-by: syzbot+5fd749c74105b0e1b302@...kaller.appspotmail.com
> Closes: https://lore.kernel.org/all/68c858b0.050a0220.3c6139.0d1c.GAE@google.com/
> Signed-off-by: Qingfang Deng <dqfext@...il.com>
> ---
> v2: add Closes tag
>  - https://lore.kernel.org/netdev/20250923060706.10232-1-dqfext@gmail.com/
> 

Thanks!

Reviewed-by: Dan Carpenter <dan.carpenter@...aro.org>

regards,
dan carpenter