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Date: Mon, 9 Oct 2023 16:55:50 +0200
From: Simon Horman <horms@kernel.org>
To: Chengfeng Ye <dg573847474@gmail.com>
Cc: jreuter@yaina.de, ralf@linux-mips.org, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	linux-hams@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2] ax25: Fix potential deadlock on &ax25_list_lock
Message-ID: <ZSQUdhzSDpAlaeXK@kernel.org>
References: <20231005072349.52602-1-dg573847474@gmail.com>
 <20231007151021.GC831234@kernel.org>
 <CAAo+4rWTq33LWgVonaK+AtZ0o_UYFLrM=ODW=hSX_VtgLvYHNw@mail.gmail.com>
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On Sat, Oct 07, 2023 at 11:43:59PM +0800, Chengfeng Ye wrote:
> Hi Simon Horman,
> 
> I think maybe not. My static analysis tool only reported this function, I
> also just manually checked the spin_lock(&ax25_list_lock) in other
> functions, and it looks like they are basically under rcv callback or timer,
> which already have BH disabled. I think the developers who wrote
> the code should be aware of this so they used spin_lock() instead of
> spin_lock_bh().
> 
> But the fixed function is a bit different, as it could be called from .ioctl(),
> which is from userland syscall and executes under the process
> context, and along the call chain BH is also not disabled explicitly. That's
> the reason why only at this place I change to spin_lock_bh().

Thanks,

I agree that seems to be the case.

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