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Date:   Sat, 7 Oct 2023 17:13:28 +0200
From:   Simon Horman <horms@kernel.org>
To:     Chengfeng Ye <dg573847474@gmail.com>
Cc:     3chas3@gmail.com, davem@davemloft.net,
        linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] atm: solos-pci: Fix potential deadlock on
 &tx_queue_lock
Message-ID: <20231007151328.GD831234@kernel.org>
References: <20231005074917.65161-1-dg573847474@gmail.com>
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On Thu, Oct 05, 2023 at 07:49:17AM +0000, Chengfeng Ye wrote:
> As &card->tx_queue_lock is acquired under softirq context along the
> following call chain from solos_bh(), other acquisition of the same
> lock inside process context should disable at least bh to avoid double
> lock.
> 
> <deadlock #2>
> pclose()
> --> spin_lock(&card->tx_queue_lock)
> <interrupt>
>    --> solos_bh()
>    --> fpga_tx()
>    --> spin_lock(&card->tx_queue_lock)
> 
> This flaw was found by an experimental static analysis tool I am
> developing for irq-related deadlock.
> 
> To prevent the potential deadlock, the patch uses spin_lock_irqsave()
> on &card->tx_queue_lock under process context code consistently to
> prevent the possible deadlock scenario.
> 
> Fixes: 213e85d38912 ("solos-pci: clean up pclose() function")
> Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
> ---
> V2: add fix tag, and split into two patches

Reviewed-by: Simon Horman <horms@kernel.org>