linux-kernel - RE: [PATCH v4 1/2] acpi/ghes: Process CXL Component Events

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Message-ID: <SJ1PR11MB6083E2C92E326D3CF41479DBFC1A2@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Tue, 30 Apr 2024 19:33:50 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: "Weiny, Ira" <ira.weiny@...el.com>
CC: "Jiang, Dave" <dave.jiang@...el.com>, "Williams, Dan J"
	<dan.j.williams@...el.com>, Jonathan Cameron <jonathan.cameron@...wei.com>,
	Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>, Shiju Jose
	<shiju.jose@...wei.com>, Dan Carpenter <dan.carpenter@...aro.org>, "Yazen
 Ghannam" <yazen.ghannam@....com>, Davidlohr Bueso <dave@...olabs.net>,
	"Schofield, Alison" <alison.schofield@...el.com>, "Verma, Vishal L"
	<vishal.l.verma@...el.com>, Ard Biesheuvel <ardb@...nel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-cxl@...r.kernel.org" <linux-cxl@...r.kernel.org>, "Rafael J. Wysocki"
	<rafael@...nel.org>, Borislav Petkov <bp@...en8.de>
Subject: RE: [PATCH v4 1/2] acpi/ghes: Process CXL Component Events

>> What's the lifetime of that record?
>>
>
> The lifetime is contained to the cxl_cper_post_envent() which does not
> block.  The kfifo_put() copies the data to a cxl specific record to be
> used by the CXL thread for processing.
>
>>
>> Can it be re-used/overwritten
>> before that other kernel thread gets around to looking at it?
>
> Yes because the CXL kernel thread has its own copy in the kfifo.

Ira,

Tracking down the call chain, doubly safe. You first copy that record to
a local variable in cxl_cper_post_event() and then kfifo_put() will copy
that copy into another place for processing.

That was my only concern.

Reviewed-by: Tony Luck <tony.luck@...el.com>

-Tony