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Commit 05ba75f8 authored by Gavin Shan's avatar Gavin Shan Committed by Michael Ellerman
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powerpc/eeh: Fix stale cached primary bus 



When PE is created, its primary bus is cached to pe->bus. At later
point, the cached primary bus is returned from eeh_pe_bus_get().
However, we could get stale cached primary bus and run into kernel
crash in one case: full hotplug as part of fenced PHB error recovery
releases all PCI busses under the PHB at unplugging time and recreate
them at plugging time. pe->bus is still dereferencing the PCI bus
that was released.

This adds another PE flag (EEH_PE_PRI_BUS) to represent the validity
of pe->bus. pe->bus is updated when its first child EEH device is
online and the flag is set. Before unplugging in full hotplug for
error recovery, the flag is cleared.

Fixes: 8cdb2833 ("powerpc/eeh: Trace PCI bus from PE")
Cc: stable@vger.kernel.org #v3.11+
Reported-by: default avatarAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Reported-by: default avatarPradipta Ghosh <pradghos@in.ibm.com>
Signed-off-by: default avatarGavin Shan <gwshan@linux.vnet.ibm.com>
Tested-by: default avatarAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 126df08c

arch/powerpc/include/asm/eeh.h

+1 −0
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ struct pci_dn; 
#define EEH_PE_KEEP		(1 << 8)	/* Keep PE on hotplug	*/

#define EEH_PE_CFG_RESTRICTED	(1 << 9)	/* Block config on error */

#define EEH_PE_REMOVED		(1 << 10)	/* Removed permanently	*/

#define EEH_PE_PRI_BUS		(1 << 11)	/* Cached primary bus   */



struct eeh_pe {

	int type;			/* PE type: PHB/Bus/Device	*/

arch/powerpc/kernel/eeh_driver.c

+3 −0
Original line number Diff line number Diff line
@@ -564,6 +564,7 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus) 
	 */

	eeh_pe_state_mark(pe, EEH_PE_KEEP);

	if (bus) {

		eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);

		pci_lock_rescan_remove();

		pcibios_remove_pci_devices(bus);

		pci_unlock_rescan_remove();
@@ -803,6 +804,7 @@ static void eeh_handle_normal_event(struct eeh_pe *pe) 
	 * the their PCI config any more.

	 */

	if (frozen_bus) {

		eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);

		eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);



		pci_lock_rescan_remove();
@@ -886,6 +888,7 @@ static void eeh_handle_special_event(void) 
					continue;



				/* Notify all devices to be down */

				eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);

				bus = eeh_pe_bus_get(phb_pe);

				eeh_pe_dev_traverse(pe,

					eeh_report_failure, NULL);

arch/powerpc/kernel/eeh_pe.c

+1 −1
Original line number Diff line number Diff line
@@ -928,7 +928,7 @@ struct pci_bus *eeh_pe_bus_get(struct eeh_pe *pe) 
		bus = pe->phb->bus;

	} else if (pe->type & EEH_PE_BUS ||

		   pe->type & EEH_PE_DEVICE) {

		if (pe->bus) {

		if (pe->state & EEH_PE_PRI_BUS) {

			bus = pe->bus;

			goto out;

		}

arch/powerpc/platforms/powernv/eeh-powernv.c

+4 −1
Original line number Diff line number Diff line
@@ -444,9 +444,12 @@ static void *pnv_eeh_probe(struct pci_dn *pdn, void *data) 
	 * PCI devices of the PE are expected to be removed prior

	 * to PE reset.

	 */

	if (!edev->pe->bus)

	if (!(edev->pe->state & EEH_PE_PRI_BUS)) {

		edev->pe->bus = pci_find_bus(hose->global_number,

					     pdn->busno);

		if (edev->pe->bus)

			edev->pe->state |= EEH_PE_PRI_BUS;

	}



	/*

	 * Enable EEH explicitly so that we will do EEH check