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From: Tong Tiangen <tongtiangen@huawei.com>
To: Andrea Parri <parri.andrea@gmail.com>
Cc: Guo Ren <guoren@kernel.org>, Jisheng Zhang <jszhang@kernel.org>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	<linux-riscv@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] riscv: fix race when vmap stack overflow
Date: Fri, 21 Oct 2022 21:46:23 +0800	[thread overview]
Message-ID: <f1eb4756-e1e1-1f12-e767-a69a891786d6@huawei.com> (raw)
In-Reply-To: <Y1KdKATQx16Xl/iL@andrea>



在 2022/10/21 21:22, Andrea Parri 写道:
> Hi Tong,
>   
>>>> I use atomic_set_release here, because I need earlier memory
>>>> operations finished to make sure the sp is ready then set the spin
>>>> flag.
> 
>> 	Consider this implementation:)
>>
>> 	smp_store_mb(&spin_shadow_stack, 0);
> 
> smp_store_mb() has "WRITE_ONCE(); smp_mb()" semantics; so it doesn't
> guarantee that the store to spin_shadow_stack is ordered after program
> -order earlier memory accesses.
> 
>    Andrea
> .

Hi Andrea:

IIUC, the earlier memory access amoswap.aqrl, here .aqrl guarantee it.
But anyway, consider we don't care about performance here, using 
smp_store_release()(add barrier()) surely right.

Thanks,
Tong.

  reply	other threads:[~2022-10-21 13:46 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-19 15:47 [PATCH] riscv: fix race when vmap stack overflow Jisheng Zhang
2022-10-20  1:02 ` Guo Ren
2022-10-20  2:16 ` Guo Ren
2022-10-20 14:38   ` Jisheng Zhang
2022-10-21  0:35     ` Guo Ren
2022-10-20 23:26 ` Andrea Parri
2022-10-21  1:11   ` Guo Ren
2022-10-21  8:36     ` Andrea Parri
2022-10-21 12:08       ` Tong Tiangen
2022-10-21 13:22         ` Andrea Parri
2022-10-21 13:46           ` Tong Tiangen [this message]
2022-10-21 14:41             ` Guo Ren
2022-10-21 15:17               ` Tong Tiangen
2022-10-21 14:35       ` Guo Ren

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