Patch "powerpc/eeh: Fix invalid cached PE primary bus" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/eeh: Fix invalid cached PE primary bus

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-eeh-fix-invalid-cached-pe-primary-bus.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Gavin Shan <[email protected]>
Date: Fri, 17 Jun 2016 13:05:11 +1000
Subject: powerpc/eeh: Fix invalid cached PE primary bus

From: Gavin Shan <[email protected]>

commit a3aa256b7258b3d19f8b44557cc64525a993b941 upstream.

The PE primary bus cannot be got from its child devices when having full hotplug in error recovery. The PE primary bus is cached, which is done in commit <05ba75f84864> ("powerpc/eeh: Fix stale cached primary bus"). In eeh_reset_device(), the flag (EEH_PE_PRI_BUS) is cleared before the PCI hot remove. eeh_pe_bus_get() then returns NULL as the PE primary bus in pnv_eeh_reset() and it crashes the kernel eventually.

This fixes the issue by clearing the flag (EEH_PE_PRI_BUS) before the PCI hot add. With it, the PowerNV EEH reset backend (pnv_eeh_reset()) can get valid PE primary bus through eeh_pe_bus_get().

---
 arch/powerpc/kernel/eeh_driver.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

@@ -648,7 +648,6 @@ static int eeh_reset_device(struct eeh_p
 		if (pe->type & EEH_PE_VF) {
 			eeh_pe_dev_traverse(pe, eeh_rmv_device, NULL);
 		} else {
-			eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);
 			pci_lock_rescan_remove();
 			pcibios_remove_pci_devices(bus);
 			pci_unlock_rescan_remove();

@@ -698,10 +697,12 @@ static int eeh_reset_device(struct eeh_p
 		 */
 		edev = list_first_entry(&pe->edevs, struct eeh_dev, list);
 		eeh_pe_traverse(pe, eeh_pe_detach_dev, NULL);
-		if (pe->type & EEH_PE_VF)
+		if (pe->type & EEH_PE_VF) {
 			eeh_add_virt_device(edev, NULL);
-		else
+		} else {
+			eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);
 			pcibios_add_pci_devices(bus);
+		}
 	} else if (frozen_bus && rmv_data->removed) {
 		pr_info("EEH: Sleep 5s ahead of partial hotplug\n");
 		ssleep(5);

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/powerpc-eeh-fix-invalid-cached-pe-primary-bus.patch