From: Borislav Petkov <bp@alien8.de>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Huang Ying <ying.huang@intel.com>, Justin He <Justin.He@arm.com>,
Len Brown <lenb@kernel.org>, James Morse <James.Morse@arm.com>,
Tony Luck <tony.luck@intel.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Robert Richter <rric@kernel.org>,
Robert Moore <robert.moore@intel.com>,
Qiuxu Zhuo <qiuxu.zhuo@intel.com>,
Yazen Ghannam <yazen.ghannam@amd.com>,
Jan Luebbe <jlu@pengutronix.de>,
Khuong Dinh <khuong@os.amperecomputing.com>,
Kani Toshi <toshi.kani@hpe.com>,
"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
"devel@acpica.org" <devel@acpica.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Shuai Xue <xueshuai@linux.alibaba.com>,
Jarkko Sakkinen <jarkko@kernel.org>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
nd <nd@arm.com>, kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v8 6/7] apei/ghes: Use unrcu_pointer for cmpxchg
Date: Fri, 14 Oct 2022 21:40:26 +0200 [thread overview]
Message-ID: <Y0m7KpdSAi6wIgfb@zn.tnic> (raw)
In-Reply-To: <CAMj1kXGQmo9xstNY9B8Mp2gujXLTqCsV1u3PQKLtHg-WpWeLDA@mail.gmail.com>
On Fri, Oct 14, 2022 at 11:40:39AM +0200, Ard Biesheuvel wrote:
> The cache struct pointer should not be published until after the
> struct itself is fully populated. So on the producer side, some kind
> of hardware barrier is definitely needed, or the struct may appear
> half-baked to other cores that can read the updated pointer.
Ah, right you are, ghes_estatus_cached() is called in all kinds of
contexts and by other cores, sure.
> OTOH the code seems to be working fine as is, so why modify it at all?
> (apart from the purely cosmetic changes)
peterz questioned that smp_wmb() there and then we started digging. And
frankly, even if removing that barrier won't make any difference, I'd
still prefer it gone and have the code simpler and cleaner.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-10-14 19:40 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-10 2:35 [PATCH v8 0/7] Make ghes_edac a proper module Jia He
2022-10-10 2:35 ` [PATCH v8 1/7] efi/cper: export several helpers for ghes_edac to use Jia He
2022-10-10 2:35 ` [PATCH v8 2/7] EDAC/ghes: Add a notifier for reporting memory errors Jia He
2022-10-10 2:35 ` [PATCH v8 3/7] EDAC/ghes: Prepare to make ghes_edac a proper module Jia He
2022-10-10 2:35 ` [PATCH v8 4/7] EDAC/ghes: Make ghes_edac a proper module to remove the dependency on ghes Jia He
2022-10-10 2:35 ` [PATCH v8 5/7] EDAC: Add the ghes_get_devices() check for chipset-specific edac drivers Jia He
2022-10-10 2:35 ` [PATCH v8 6/7] apei/ghes: Use unrcu_pointer for cmpxchg Jia He
2022-10-11 10:33 ` Borislav Petkov
2022-10-11 14:32 ` Justin He
2022-10-11 14:45 ` Borislav Petkov
2022-10-12 4:35 ` Justin He
2022-10-12 12:04 ` Justin He
2022-10-13 13:37 ` Borislav Petkov
2022-10-13 15:41 ` Ard Biesheuvel
2022-10-13 16:37 ` Borislav Petkov
2022-10-13 16:45 ` Peter Zijlstra
2022-10-13 17:42 ` Borislav Petkov
2022-10-14 9:40 ` Ard Biesheuvel
2022-10-14 19:40 ` Borislav Petkov [this message]
2022-10-14 12:00 ` Justin He
2022-10-14 14:31 ` Ard Biesheuvel
2022-10-14 15:10 ` Peter Zijlstra
2022-10-14 15:24 ` Ard Biesheuvel
2022-10-17 8:47 ` Justin He
2022-10-17 9:27 ` Ard Biesheuvel
2022-10-17 11:57 ` Justin He
2022-10-13 16:41 ` Peter Zijlstra
2022-10-10 2:35 ` [PATCH v8 7/7] EDAC/igen6: Return consistent errno when another edac driver is enabled Jia He
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