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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
Date: Sun, 10 Mar 2024 21:19:10 +0200	[thread overview]
Message-ID: <20240310191910.GG12921@unreal> (raw)
In-Reply-To: <tencent_49503CC554528271302D9D214218898E4206@qq.com>

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

  reply	other threads:[~2024-03-10 19:19 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-09 12:27 [PATCH] RDMA/siw: Reuse value read using READ_ONCE instead of re-reading it linke li
2024-03-10  4:53 ` Zhu Yanjun
2024-03-10 12:36   ` linke li
2024-03-10 17:00     ` Greg Sword
2024-03-11  2:57       ` linke li
2024-03-11  8:17         ` Zhu Yanjun
2024-03-10 11:33 ` Leon Romanovsky
2024-03-10 12:15   ` linke li
2024-03-10 19:19     ` Leon Romanovsky [this message]
2024-03-11  2:34       ` linke li
2024-03-11  5:11         ` Zhu Yanjun
2024-03-10 17:02   ` Greg Sword
2024-03-11 14:14 ` Bernard Metzler
2024-03-12  1:30   ` linke li
2024-03-12  7:57     ` Leon Romanovsky

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