Hi Borislav > -----Original Message----- > From: Borislav Petkov <bp@xxxxxxxxx> > Sent: Tuesday, October 11, 2022 10:46 PM > To: Justin He <Justin.He@xxxxxxx> > Cc: Len Brown <lenb@xxxxxxxxxx>; James Morse <James.Morse@xxxxxxx>; > Tony Luck <tony.luck@xxxxxxxxx>; Mauro Carvalho Chehab > <mchehab@xxxxxxxxxx>; Robert Richter <rric@xxxxxxxxxx>; Robert Moore > <robert.moore@xxxxxxxxx>; Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>; Yazen > Ghannam <yazen.ghannam@xxxxxxx>; Jan Luebbe <jlu@xxxxxxxxxxxxxx>; > Khuong Dinh <khuong@xxxxxxxxxxxxxxxxxxxxxx>; Kani Toshi > <toshi.kani@xxxxxxx>; Ard Biesheuvel <ardb@xxxxxxxxxx>; > linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-edac@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; Rafael J . Wysocki > <rafael@xxxxxxxxxx>; Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>; Jarkko > Sakkinen <jarkko@xxxxxxxxxx>; linux-efi@xxxxxxxxxxxxxxx; nd <nd@xxxxxxx>; > kernel test robot <lkp@xxxxxxxxx> > 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)
