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Date: Sun, 10 Mar 2024 21:19:10 +0200
From: Leon Romanovsky <leon@kernel.org>
To: linke li <lilinke99@qq.com>
Cc: bmt@zurich.ibm.com, jgg@ziepe.ca, linux-kernel@vger.kernel.org,
	linux-rdma@vger.kernel.org
Subject: Re: [PATCH] RDMA/siw: Reuse value read using READ_ONCE instead of
 re-reading it
Message-ID: <20240310191910.GG12921@unreal>
References: <20240310113306.GF12921@unreal>
 <tencent_49503CC554528271302D9D214218898E4206@qq.com>
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On Sun, Mar 10, 2024 at 08:15:25PM +0800, linke li wrote:
> I want to emphasize that if the value of orqe->flags has changed by the
> time of the second read, the value read will not satisfy the if condition,
> causing inconsistency. Given that there is already a READ_ONCE.

If value can change between subsequent reads, then you need to use locks
to make sure that it doesn't happen. Using READ_ONCE() doesn't solve the
concurrency issue, but makes sure that compiler doesn't reorder reads
and writes.

Thanks