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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: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Naveen N. Rao 2013-06-25 23:58:59 +05:30 committed by Tony Luck
parent 9e895ace5d
commit 0644414e62
2 changed files with 16 additions and 1 deletions
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5
arch/x86/kernel/cpu/mcheck/mce.c
View File

@ -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
};

12
arch/x86/kernel/cpu/mcheck/mce_intel.c
View File

@ -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);
/*