Re: [PATCH 4/4] x86/mce/AMD: Add comments for easier understanding

From: Aravind Gopalakrishnan
Date: Wed Feb 24 2016 - 13:26:58 EST

On 2/23/2016 6:35 AM, Borislav Petkov wrote:
On Tue, Feb 16, 2016 at 03:45:11PM -0600, Aravind Gopalakrishnan wrote:
+ * Set the error_count and interrupt_enable sysfs attributes here.
+ * This function gets called during the init phase and when someone
+ * makes changes to either of the sysfs attributes.
+ * During init phase, we also program Interrupt type as 'APIC' and
+ * verify if LVT offset obtained from MCx_MISC is valid.
* Called via smp_call_function_single(), must be called with correct
* cpu affinity.
I don't think that's what threshold_restart_bank() does...

Hmm, we call this from mce_threshold_block_init() with set_lvt_off = 1 to write LVT offset value to MCi_MISC.
And we call this from store_interrupt_enable() to program APIC INT TYPE-
if (tr->b->interrupt_enable)

and from store_threshold_limit() to re-set the "error count"-
hi = (hi & ~MASK_ERR_COUNT_HI) |
(new_count & THRESHOLD_MAX);

So I thought it fit the description as to "what" it does..

Also, that comment is too much - it shouldn't explain "what" but "why".

How about-

"This function provides user with capabilities to re-program the 'thresold_limit' and 'interrupt_enable' sysfs attributes"

@@ -262,6 +267,11 @@ static int setup_APIC_deferred_error(int reserved, int new)
return reserved;
+ * Obtain LVT offset from MSR_CU_DEF_ERR and call
+ * setup_APIC_deferred_error() to program relevant APIC register.
+ * Also, register a deferred error interrupt handler
+ */
No, that's basically spelling what the code does.

Ok, I'll remove this.

static void deferred_error_interrupt_enable(struct cpuinfo_x86 *c)
u32 low = 0, high = 0;
@@ -338,6 +348,14 @@ nextaddr_out:
return addr;
+ * struct threshold_block descriptor tracks useful info regarding the
+ * banks' MISC register. Among other things, it tracks whether interrupt
+ * is possible for the given bank, the threshold limit and the sysfs object
+ * that outputs these info.
That should be in form of comments explaining what the members of struct
threshold_block are, where that struct is defined.

Ok, I'll remove comments here and add it to arch/x86/include/asm/amd_nb.h

Initializing the struct here, programming
+ * LVT offset for threshold interrupts and registering a interrupt handler
+ * if we haven't already done so
Also spelling the code.

Will remove this