Re: [PATCH v3 2/2] powerpc/eeh: Clean up and document event handling functions

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Wed, Apr 19, 2017 at 05:39:27PM +1000, Russell Currey wrote:
>Remove unnecessary tags in eeh_handle_normal_event(), and add function
>comments for eeh_handle_normal_event() and eeh_handle_special_event().
>
>The only functional difference is that in the case of a PE reaching the
>maximum number of failures, rather than one message telling you of this
>and suggesting you reseat the device, there are two separate messages.
>
>Suggested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>Signed-off-by: Russell Currey <ruscur@russell.cc>
>---
>V3: new.  Thanks to Alexey for the suggestions.
>---
> arch/powerpc/kernel/eeh_driver.c | 36 ++++++++++++++++++++++++------------
> 1 file changed, 24 insertions(+), 12 deletions(-)
>
>diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
>index e50d1470714f..c405c79e50cd 100644
>--- a/arch/powerpc/kernel/eeh_driver.c
>+++ b/arch/powerpc/kernel/eeh_driver.c
>@@ -724,6 +724,15 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus,
>  */
> #define MAX_WAIT_FOR_RECOVERY 300
>
>+/**
>+ * eeh_handle_normal_event - Handle EEH events on a specific PE
>+ * @pe: EEH PE
>+ *
>+ * Attempts to recover the given PE.  If recovery fails or the PE has failed
>+ * too many times, remove the PE.
>+ *
>+ * Returns true if @pe should no longer be used, else false.
>+ */

I think this bit of comments would be part of PATCH[1/2]? Also, the
comments needn't to be in any document as it's static one. I guess
you might not want it to show in stable branches as PATCH[1/2] has
been tagged as stable. It's fine if that's the case.

> static bool eeh_handle_normal_event(struct eeh_pe *pe)
> {
> 	struct pci_bus *frozen_bus;
>@@ -741,8 +750,13 @@ static bool eeh_handle_normal_event(struct eeh_pe *pe)
>
> 	eeh_pe_update_time_stamp(pe);
> 	pe->freeze_count++;
>-	if (pe->freeze_count > eeh_max_freezes)
>-		goto excess_failures;
>+	if (pe->freeze_count > eeh_max_freezes) {
>+		pr_err("EEH: PHB#%x-PE#%x has failed %d times in the\n"
>+		       "last hour and has been permanently disabled.\n",
>+		       pe->phb->global_number, pe->addr,
>+		       pe->freeze_count);
>+		goto hard_fail;
>+	}
> 	pr_warn("EEH: This PCI device has failed %d times in the last hour\n",
> 		pe->freeze_count);
>
>@@ -872,25 +886,16 @@ static bool eeh_handle_normal_event(struct eeh_pe *pe)
>
> 	return false;
>
>-excess_failures:
>+hard_fail:
> 	/*
> 	 * About 90% of all real-life EEH failures in the field
> 	 * are due to poorly seated PCI cards. Only 10% or so are
> 	 * due to actual, failed cards.
> 	 */

This bit of comments apply to "excess_failures" only, so it would
be moved together with the pr_err(). Frankly speaking, I don't see
the benebit of the cleanup. "excess_failure" in the original code
indicates the case (excessive failures) explicitly, which is nice.
However, it's not a big deal.

>-	pr_err("EEH: PHB#%x-PE#%x has failed %d times in the\n"
>-	       "last hour and has been permanently disabled.\n"
>-	       "Please try reseating or replacing it.\n",
>-		pe->phb->global_number, pe->addr,
>-		pe->freeze_count);
>-	goto perm_error;
>-
>-hard_fail:
> 	pr_err("EEH: Unable to recover from failure from PHB#%x-PE#%x.\n"
> 	       "Please try reseating or replacing it\n",
> 		pe->phb->global_number, pe->addr);
>
>-perm_error:

We will have the message from above pr_err() for "perm_error" case, but
we don't have that in original code.

> 	eeh_slot_error_detail(pe, EEH_LOG_PERM);
>
> 	/* Notify all devices that they're about to go down. */
>@@ -923,6 +928,13 @@ static bool eeh_handle_normal_event(struct eeh_pe *pe)
> 	return false;
> }
>
>+/**
>+ * eeh_handle_special_event - Handle EEH events without a specific failing PE
>+ *
>+ * Called when an EEH event is detected but can't be narrowed down to a
>+ * specific PE.  Iterates through possible failures and handles them as
>+ * necessary.
>+ */
> static void eeh_handle_special_event(void)
> {
> 	struct eeh_pe *pe, *phb_pe;

Thanks,
Gavin