linux-kernel - RE: [PATCH v2 1/2] mce: acpi/apei: Honour Firmware First for MCA banks listed in APEI HEST CMC

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Message-ID: <3908561D78D1C84285E8C5FCA982C28F31C54AF9@ORSMSX106.amr.corp.intel.com>
Date:	Tue, 25 Jun 2013 17:55:27 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
	"bp@...en8.de" <bp@...en8.de>
CC:	"ananth@...ibm.com" <ananth@...ibm.com>,
	"masbock@...ux.vnet.ibm.com" <masbock@...ux.vnet.ibm.com>,
	"lcm@...ux.vnet.ibm.com" <lcm@...ux.vnet.ibm.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>
Subject: RE: [PATCH v2 1/2] mce: acpi/apei: Honour Firmware First for MCA
 banks listed in APEI HEST CMC

+/*
+ * Indicates MCA banks controlled by the current cpu for CMCI. Note that this
+ * can change when a cpu is offlined or brought online since some MCA banks
+ * are shared across cpus. When a cpu is offlined, cmci_clear() disables CMCI
+ * on all banks owned by the cpu and clears this bitfield. At this point,
+ * cmci_rediscover() kicks in and a different cpu may end up taking
+ * ownership of some of the shared MCA banks that were previously owned
+ * by the offlined cpu.
+ */
 static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned);

Maybe an extra sentence or two at the beginning to say *why* we need this.
E.g.

/*
 * CMCI can be delivered to multiple cpus that share a machine check bank
 * so we need to designate a single cpu to process errors logged in each bank
 * in the interrupt handler (otherwise we would have many races and potential
 * double reporting of the same error.
 */
...

-Tony