Messages in this thread | | | From | Justin He <> | Subject | RE: [PATCH v8 6/7] apei/ghes: Use unrcu_pointer for cmpxchg | Date | Wed, 12 Oct 2022 12:04:57 +0000 |
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Hi Borislav
> -----Original Message----- > From: Borislav Petkov <bp@alien8.de> > Sent: Tuesday, October 11, 2022 10:46 PM > To: Justin He <Justin.He@arm.com> > Cc: 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>; Ard Biesheuvel <ardb@kernel.org>; > linux-acpi@vger.kernel.org; linux-kernel@vger.kernel.org; > linux-edac@vger.kernel.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; nd <nd@arm.com>; > kernel test robot <lkp@intel.com> > Subject: Re: [PATCH v8 6/7] apei/ghes: Use unrcu_pointer for cmpxchg > > On Tue, Oct 11, 2022 at 02:32:48PM +0000, Justin He wrote: > > My original purpose is to make it pass the sparse checking. > > Then do this pls. > > This is a combined diff - do a second patch which does only remove the > smp_wmb(). The smp_wmb() there is not needed as the cmpxchg() already > implies a smp_mb() so there's no need for that separate, explicit one. > I have a concern about what if cmpxchg failed? Do we have to still guarantee the ordering since cmpxchg will not imply a smp_mb if it failed.
Besides, I didn't find the paired smp_mb or smp_rmb for this smp_wmb. Do you have any ideas?
-- Cheers, Justin (Jia He)
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