linux-kernel - RE: [PATCH v13 1/2] ACPI / APEI: Add a notifier chain for unknown (vendor) CPER records

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Date:   Fri, 24 Jul 2020 13:32:52 +0000
From:   Shiju Jose <shiju.jose@...wei.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
CC:     "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "bp@...en8.de" <bp@...en8.de>,
        "james.morse@....com" <james.morse@....com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "dan.carpenter@...cle.com" <dan.carpenter@...cle.com>,
        "zhangliguang@...ux.alibaba.com" <zhangliguang@...ux.alibaba.com>,
        "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        "Wangkefeng (OS Kernel Lab)" <wangkefeng.wang@...wei.com>,
        "jroedel@...e.de" <jroedel@...e.de>,
        Linuxarm <linuxarm@...wei.com>,
        yangyicong <yangyicong@...wei.com>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        tanxiaofei <tanxiaofei@...wei.com>
Subject: RE: [PATCH v13 1/2] ACPI / APEI: Add a notifier chain for unknown
 (vendor) CPER records

>-----Original Message-----
>From: Bjorn Helgaas [mailto:helgaas@...nel.org]
>Sent: 24 July 2020 13:54
>To: Shiju Jose <shiju.jose@...wei.com>
>Cc: linux-acpi@...r.kernel.org; linux-pci@...r.kernel.org; linux-
>kernel@...r.kernel.org; rjw@...ysocki.net; bp@...en8.de;
>james.morse@....com; lenb@...nel.org; tony.luck@...el.com;
>dan.carpenter@...cle.com; zhangliguang@...ux.alibaba.com;
>andriy.shevchenko@...ux.intel.com; Wangkefeng (OS Kernel Lab)
><wangkefeng.wang@...wei.com>; jroedel@...e.de; Linuxarm
><linuxarm@...wei.com>; yangyicong <yangyicong@...wei.com>; Jonathan
>Cameron <jonathan.cameron@...wei.com>; tanxiaofei
><tanxiaofei@...wei.com>
>Subject: Re: [PATCH v13 1/2] ACPI / APEI: Add a notifier chain for unknown
>(vendor) CPER records
>
>On Fri, Jul 24, 2020 at 09:00:41AM +0000, Shiju Jose wrote:
>> >-----Original Message-----
>> >From: Bjorn Helgaas [mailto:helgaas@...nel.org]
>> >Sent: 24 July 2020 00:21
>> >To: Shiju Jose <shiju.jose@...wei.com>
>> >Cc: linux-acpi@...r.kernel.org; linux-pci@...r.kernel.org; linux-
>> >kernel@...r.kernel.org; rjw@...ysocki.net; bp@...en8.de;
>> >james.morse@....com; lenb@...nel.org; tony.luck@...el.com;
>> >dan.carpenter@...cle.com; zhangliguang@...ux.alibaba.com;
>> >andriy.shevchenko@...ux.intel.com; Wangkefeng (OS Kernel Lab)
>> ><wangkefeng.wang@...wei.com>; jroedel@...e.de; Linuxarm
>> ><linuxarm@...wei.com>; yangyicong <yangyicong@...wei.com>;
>Jonathan
>> >Cameron <jonathan.cameron@...wei.com>; tanxiaofei
>> ><tanxiaofei@...wei.com>
>> >Subject: Re: [PATCH v13 1/2] ACPI / APEI: Add a notifier chain for
>> >unknown
>> >(vendor) CPER records
>> >
>> >On Wed, Jul 22, 2020 at 11:39:51AM +0100, Shiju Jose wrote:
>> >> CPER records describing a firmware-first error are identified by GUID.
>> >> The ghes driver currently logs, but ignores any unknown CPER records.
>> >> This prevents describing errors that can't be represented by a
>> >> standard entry, that would otherwise allow a driver to recover from
>> >> an
>> >error.
>> >> The UEFI spec calls these 'Non-standard Section Body' (N.2.3 of
>> >> version 2.8).
>> >
>> >> +#ifdef CONFIG_ACPI_APEI_GHES
>> >> +/**
>> >> + * ghes_register_vendor_record_notifier - register a notifier for
>> >> +vendor
>> >> + * records that the kernel would otherwise ignore.
>> >> + * @nb: pointer to the notifier_block structure of the event handler.
>> >> + *
>> >> + * return 0 : SUCCESS, non-zero : FAIL  */ int
>> >> +ghes_register_vendor_record_notifier(struct notifier_block *nb);
>> >> +
>> >> +/**
>> >> + * ghes_unregister_vendor_record_notifier - unregister the
>> >> +previously
>> >> + * registered vendor record notifier.
>> >> + * @nb: pointer to the notifier_block structure of the vendor
>> >> +record
>> >handler.
>> >> + */
>> >> +void ghes_unregister_vendor_record_notifier(struct notifier_block
>> >> +*nb); #else static inline int
>> >> +ghes_register_vendor_record_notifier(struct notifier_block *nb) {
>> >> +	return -ENODEV;
>> >> +}
>> >> +
>> >> +static inline void ghes_unregister_vendor_record_notifier(struct
>> >> +notifier_block *nb) { }
>> >
>> >If you made CONFIG_PCIE_HISI_ERR depend on CONFIG_ACPI_APEI_GHES,
>> >you'd be able to get rid of these stubs, wouldn't you?  It doesn't
>> >look like there's any point in building pcie-hisi-error.c at all
>> >unless CONFIG_ACPI_APEI_GHES is enabled.
>>
>> The stub is added because this interface is expected to use by the
>> other drivers as well.  Some drivers may not want add the build depend
>> on the CONFIG_ACPI_APEI_GHES if the error reporting has less priority
>> in the driver.  However we can add dependency on
>CONFIG_ACPI_APEI_GHES
>> for building pcie-hisi-error.c.
>
>The usual route is to add stubs when they're needed, not just in anticipation
>of some need that may never materialize.
ok. I will change in the next version.

Thanks,
Shiju