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Date: Wed, 15 Jul 2026 12:43:15 +0100
From: Simon Horman <horms@kernel.org>
To: xuanqiang.luo@linux.dev
Cc: David Howells <dhowells@redhat.com>,
	Marc Dionne <marc.dionne@auristor.com>, netdev@vger.kernel.org,
	linux-afs@lists.infradead.org,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	linux-kernel@vger.kernel.org,
	Xuanqiang Luo <luoxuanqiang@kylinos.cn>
Subject: Re: [PATCH net v1] rxrpc: fix io_thread race in
 rxrpc_wake_up_io_thread()
Message-ID: <20260715114315.GO1364329@horms.kernel.org>
References: <20260708093534.53486-1-xuanqiang.luo@linux.dev>
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In-Reply-To: <20260708093534.53486-1-xuanqiang.luo@linux.dev>

On Wed, Jul 08, 2026 at 05:35:34PM +0800, xuanqiang.luo@linux.dev wrote:
> From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
> 
> rxrpc_wake_up_io_thread() checks local->io_thread before waking it, but
> then reloads the pointer for wake_up_process().
> 
> local->io_thread is cleared with WRITE_ONCE() when the I/O thread exits, so
> the second load can see NULL even if the first load did not.
> 
> Take a READ_ONCE() snapshot and use it for both the NULL check and the
> wake_up_process() call, as rxrpc_encap_rcv() already does.
> 
> Fixes: 5800b1cf3fd8 ("rxrpc: Allow CHALLENGEs to the passed to the app for a RESPONSE")
> Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

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