From: "Arnd Bergmann" <arnd@arndb.de>
To: "Xu Lu" <luxu.kernel@bytedance.com>
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
"Anup Patel" <anup@brainfault.org>,
"Charlie Jenkins" <charlie@rivosinc.com>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
lihangjing@bytedance.com, "Xie Yongji" <xieyongji@bytedance.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [External] Re: [PATCH RESEND] irqchip: riscv: Order normal writes and IPI writes
Date: Mon, 27 Jan 2025 20:07:55 +0100 [thread overview]
Message-ID: <7811b481-0227-42bb-a5ce-1d9794f5a196@app.fastmail.com> (raw)
In-Reply-To: <CAPYmKFtx6GNE5r-R33aiHeF-qgFESH0sbsorttjJ88wTL8yr9w@mail.gmail.com>
On Mon, Jan 27, 2025, at 17:37, Xu Lu wrote:
> On Tue, Jan 28, 2025 at 12:23 AM Arnd Bergmann <arnd@arndb.de> wrote:
>> On Mon, Jan 27, 2025, at 10:38, Xu Lu wrote:
>>
>> thead_aclint_sswi_ipi_clear() seems to have the same bug,
>> it also uses the _relaxed() version for no apparent reason.
>
>
> There seems no need to modify thead_aclint_sswi_ipi_clear() as it only
> clears pending IPI on current hart. No other harts require to see
> strict order between preceding memory writes and this ACLINT MMIO
> write. Please correct me if I missed anything.
My point was that you should always default to the normal operations,
since the relaxed ones keep causing problems. If you still think it's
important to use writel_relaxed() in thead_aclint_sswi_ipi_clear(),
please add a comment explaining how you have shown that it's correct
and why it matters, otherwise convert them both.
Arnd
prev parent reply other threads:[~2025-01-27 19:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-27 9:38 Xu Lu
2025-01-27 10:13 ` [tip: irq/urgent] irqchip/riscv: Ensure ordering of memory " tip-bot2 for Xu Lu
2025-01-27 10:33 ` [PATCH RESEND] irqchip: riscv: Order normal " Thomas Gleixner
2025-01-27 14:26 ` [External] " Xu Lu
2025-01-27 16:21 ` Arnd Bergmann
2025-01-27 16:37 ` [External] " Xu Lu
2025-01-27 19:07 ` Arnd Bergmann [this message]
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