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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: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reported-by: Pradipta Ghosh <pradghos@in.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Gavin Shan 2016-02-09 15:50:21 +11:00 committed by Michael Ellerman
parent 126df08c52
commit 05ba75f848
4 changed files with 9 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/powerpc/include/asm/eeh.h
View File

@ -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 */

3
arch/powerpc/kernel/eeh_driver.c
View File

@ -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 @@ perm_error:
* 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);

2
arch/powerpc/kernel/eeh_pe.c
View File

@ -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;
}

5
arch/powerpc/platforms/powernv/eeh-powernv.c
View File

@ -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