linux-kernel - RE: [PATCH v8 6/7] apei/ghes: Use unrcu

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Message-ID: <DBBPR08MB4538A9F831FA96545BA35D9FF7239@DBBPR08MB4538.eurprd08.prod.outlook.com>
Date:   Tue, 11 Oct 2022 14:32:48 +0000
From:   Justin He <Justin.He@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     Len Brown <lenb@...nel.org>, James Morse <James.Morse@....com>,
        Tony Luck <tony.luck@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Richter <rric@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Qiuxu Zhuo <qiuxu.zhuo@...el.com>,
        Yazen Ghannam <yazen.ghannam@....com>,
        Jan Luebbe <jlu@...gutronix.de>,
        Khuong Dinh <khuong@...amperecomputing.com>,
        Kani Toshi <toshi.kani@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "devel@...ica.org" <devel@...ica.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Shuai Xue <xueshuai@...ux.alibaba.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        nd <nd@....com>, kernel test robot <lkp@...el.com>
Subject: RE: [PATCH v8 6/7] apei/ghes: Use unrcu_pointer for cmpxchg

Hi Borislav

> -----Original Message-----
> From: Borislav Petkov <bp@...en8.de>
> Sent: Tuesday, October 11, 2022 6:34 PM
> To: Justin He <Justin.He@....com>
> Cc: Len Brown <lenb@...nel.org>; James Morse <James.Morse@....com>;
> Tony Luck <tony.luck@...el.com>; Mauro Carvalho Chehab
> <mchehab@...nel.org>; Robert Richter <rric@...nel.org>; Robert Moore
> <robert.moore@...el.com>; Qiuxu Zhuo <qiuxu.zhuo@...el.com>; Yazen
> Ghannam <yazen.ghannam@....com>; Jan Luebbe <jlu@...gutronix.de>;
> Khuong Dinh <khuong@...amperecomputing.com>; Kani Toshi
> <toshi.kani@....com>; Ard Biesheuvel <ardb@...nel.org>;
> linux-acpi@...r.kernel.org; linux-kernel@...r.kernel.org;
> linux-edac@...r.kernel.org; devel@...ica.org; Rafael J . Wysocki
> <rafael@...nel.org>; Shuai Xue <xueshuai@...ux.alibaba.com>; Jarkko
> Sakkinen <jarkko@...nel.org>; linux-efi@...r.kernel.org; nd <nd@....com>;
> kernel test robot <lkp@...el.com>
> Subject: Re: [PATCH v8 6/7] apei/ghes: Use unrcu_pointer for cmpxchg
> 
> On Mon, Oct 10, 2022 at 02:35:58AM +0000, Jia He wrote:
> > ghes_estatus_caches should be add rcu annotation to avoid sparse warnings.
> >    drivers/acpi/apei/ghes.c:733:25: sparse: sparse: incompatible types in
> comparison expression (different address spaces):
> >    drivers/acpi/apei/ghes.c:733:25: sparse:    struct ghes_estatus_cache
> [noderef] __rcu *
> >    drivers/acpi/apei/ghes.c:733:25: sparse:    struct ghes_estatus_cache *
> >    drivers/acpi/apei/ghes.c:813:25: sparse: sparse: incompatible types in
> comparison expression (different address spaces):
> >    drivers/acpi/apei/ghes.c:813:25: sparse:    struct ghes_estatus_cache
> [noderef] __rcu *
> >    drivers/acpi/apei/ghes.c:813:25: sparse:    struct ghes_estatus_cache *
> >
> > unrcu_pointer is to strip the __rcu in cmpxchg.
> 
> Is this only to shut up sparse or actually fixing anything?

My original purpose is to make it pass the sparse checking. 

--
Cheers,
Justin (Jia He)