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Commit 0644414e authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Tony Luck
Browse files

mce: acpi/apei: Add comments to clarify usage of the various bitfields in the MCA subsystem 



There is some confusion about the 'mce_poll_banks' and 'mce_banks_owned'
per-cpu bitmaps.  Provide comments so that we all know exactly what these
are used for, and why.

Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 9e895ace

arch/x86/kernel/cpu/mcheck/mce.c

+4 −1
Original line number Diff line number Diff line
@@ -89,7 +89,10 @@ static DECLARE_WAIT_QUEUE_HEAD(mce_chrdev_wait); 
static DEFINE_PER_CPU(struct mce, mces_seen);

static int			cpu_missing;



/* MCA banks polled by the period polling timer for corrected events */

/*

 * MCA banks polled by the period polling timer for corrected events.

 * With Intel CMCI, this only has MCA banks which do not support CMCI (if any).

 */

DEFINE_PER_CPU(mce_banks_t, mce_poll_banks) = {

	[0 ... BITS_TO_LONGS(MAX_NR_BANKS)-1] = ~0UL

};

arch/x86/kernel/cpu/mcheck/mce_intel.c

+12 −0
Original line number Diff line number Diff line
@@ -24,6 +24,18 @@ 
 * Also supports reliable discovery of shared banks.

 */



/*

 * 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).

 * 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);



/*