4 files changed, 64 insertions, 26 deletions

diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
index c13119a5e69b..9d0e1694a94d 100644
--- a/arch/powerpc/include/asm/eeh.h
+++ b/arch/powerpc/include/asm/eeh.h
@@ -88,6 +88,17 @@ struct eeh_pe {
 	struct list_head child_list;	/* List of PEs below this PE	*/
 	struct list_head child;		/* Memb. child_list/eeh_phb_pe	*/
 	struct list_head edevs;		/* List of eeh_dev in this PE	*/
+
+	/*
+	 * Saved stack trace. When we find a PE freeze in eeh_dev_check_failure
+	 * the stack trace is saved here so we can print it in the recovery
+	 * thread if it turns out to due to a real problem rather than
+	 * a hot-remove.
+	 *
+	 * A max of 64 entries might be overkill, but it also might not be.
+	 */
+	unsigned long stack_trace[64];
+	int trace_entries;
 };
 
 #define eeh_pe_for_each_dev(pe, edev, tmp) \
diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 7b2755f5c6fd..398def61f8a6 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -420,11 +420,9 @@ static int eeh_phb_check_failure(struct eeh_pe *pe)
 	eeh_pe_mark_isolated(phb_pe);
 	eeh_serialize_unlock(flags);
 
-	pr_err("EEH: PHB#%x failure detected, location: %s\n",
+	pr_debug("EEH: PHB#%x failure detected, location: %s\n",
 		phb_pe->phb->global_number, eeh_pe_loc_get(phb_pe));
-	dump_stack();
 	eeh_send_failure_event(phb_pe);
-
 	return 1;
 out:
 	eeh_serialize_unlock(flags);
@@ -451,7 +449,7 @@ int eeh_dev_check_failure(struct eeh_dev *edev)
 	unsigned long flags;
 	struct device_node *dn;
 	struct pci_dev *dev;
-	struct eeh_pe *pe, *parent_pe, *phb_pe;
+	struct eeh_pe *pe, *parent_pe;
 	int rc = 0;
 	const char *location = NULL;
 
@@ -581,13 +579,8 @@ int eeh_dev_check_failure(struct eeh_dev *edev)
 	 * a stack trace will help the device-driver authors figure
 	 * out what happened.  So print that out.
 	 */
-	phb_pe = eeh_phb_pe_get(pe->phb);
-	pr_err("EEH: Frozen PHB#%x-PE#%x detected\n",
-	       pe->phb->global_number, pe->addr);
-	pr_err("EEH: PE location: %s, PHB location: %s\n",
-	       eeh_pe_loc_get(pe), eeh_pe_loc_get(phb_pe));
-	dump_stack();
-
+	pr_debug("EEH: %s: Frozen PHB#%x-PE#%x detected\n",
+		__func__, pe->phb->global_number, pe->addr);
 	eeh_send_failure_event(pe);
 
 	return 1;
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index 52ce7584af43..0d34cc12c529 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -863,8 +863,44 @@ void eeh_handle_normal_event(struct eeh_pe *pe)
 			if (eeh_slot_presence_check(edev->pdev))
 				devices++;
 
-	if (!devices)
+	if (!devices) {
+		pr_debug("EEH: Frozen PHB#%x-PE#%x is empty!\n",
+			pe->phb->global_number, pe->addr);
 		goto out; /* nothing to recover */
+	}
+
+	/* Log the event */
+	if (pe->type & EEH_PE_PHB) {
+		pr_err("EEH: PHB#%x failure detected, location: %s\n",
+			pe->phb->global_number, eeh_pe_loc_get(pe));
+	} else {
+		struct eeh_pe *phb_pe = eeh_phb_pe_get(pe->phb);
+
+		pr_err("EEH: Frozen PHB#%x-PE#%x detected\n",
+		       pe->phb->global_number, pe->addr);
+		pr_err("EEH: PE location: %s, PHB location: %s\n",
+		       eeh_pe_loc_get(pe), eeh_pe_loc_get(phb_pe));
+	}
+
+	/*
+	 * Print the saved stack trace now that we've verified there's
+	 * something to recover.
+	 */
+	if (pe->trace_entries) {
+		void **ptrs = (void **) pe->stack_trace;
+		int i;
+
+		pr_err("EEH: Frozen PHB#%x-PE#%x detected\n",
+		       pe->phb->global_number, pe->addr);
+
+		/* FIXME: Use the same format as dump_stack() */
+		pr_err("EEH: Call Trace:\n");
+		for (i = 0; i < pe->trace_entries; i++)
+			pr_err("EEH: [%pK] %pS\n", ptrs[i], ptrs[i]);
+
+		pe->trace_entries = 0;
+	}
+
 
 	eeh_pe_update_time_stamp(pe);
 	pe->freeze_count++;
diff --git a/arch/powerpc/kernel/eeh_event.c b/arch/powerpc/kernel/eeh_event.c
index e36653e5f76b..1d55486adb0f 100644
--- a/arch/powerpc/kernel/eeh_event.c
+++ b/arch/powerpc/kernel/eeh_event.c
@@ -40,7 +40,6 @@ static int eeh_event_handler(void * dummy)
 {
 	unsigned long flags;
 	struct eeh_event *event;
-	struct eeh_pe *pe;
 
 	while (!kthread_should_stop()) {
 		if (wait_for_completion_interruptible(&eeh_eventlist_event))
@@ -59,19 +58,10 @@ static int eeh_event_handler(void * dummy)
 			continue;
 
 		/* We might have event without binding PE */
-		pe = event->pe;
-		if (pe) {
-			if (pe->type & EEH_PE_PHB)
-				pr_info("EEH: Detected error on PHB#%x\n",
-					 pe->phb->global_number);
-			else
-				pr_info("EEH: Detected PCI bus error on "
-					"PHB#%x-PE#%x\n",
-					pe->phb->global_number, pe->addr);
-			eeh_handle_normal_event(pe);
-		} else {
+		if (event->pe)
+			eeh_handle_normal_event(event->pe);
+		else
 			eeh_handle_special_event();
-		}
 
 		kfree(event);
 	}
@@ -126,8 +116,16 @@ int __eeh_send_failure_event(struct eeh_pe *pe)
 	 * This prevents the PE from being free()ed by a hotplug driver
 	 * while the PE is sitting in the event queue.
 	 */
-	if (pe)
+	if (pe) {
+		/*
+		 * Save the current stack trace so we can dump it from the
+		 * event handler thread.
+		 */
+		pe->trace_entries = stack_trace_save(pe->stack_trace,
+					 ARRAY_SIZE(pe->stack_trace), 0);
+
 		eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
+	}
 
 	/* We may or may not be called in an interrupt context */
 	spin_lock_irqsave(&eeh_eventlist_lock, flags);