From: Sam Bobroff sbobroff@linux.ibm.com
commit d4f194ed9eb9841a8f978710e4d24296f791a85b upstream.
Recovering a dead PHB can currently cause a deadlock as the PCI rescan/remove lock is taken twice.
This is caused as part of an existing bug in eeh_handle_special_event(). The pe is processed while traversing the PHBs even though the pe is unrelated to the loop. This causes the pe to be, incorrectly, processed more than once.
Untangling this section can move the pe processing out of the loop and also outside the locked section, correcting both problems.
Fixes: 2e25505147b8 ("powerpc/eeh: Fix crash when edev->pdev changes") Cc: stable@vger.kernel.org # 5.4+ Signed-off-by: Sam Bobroff sbobroff@linux.ibm.com Reviewed-by: Frederic Barrat fbarrat@linux.ibm.com Tested-by: Frederic Barrat fbarrat@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/0547e82dbf90ee0729a2979a8cac5c91665c621f.158105144... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/kernel/eeh_driver.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
--- a/arch/powerpc/kernel/eeh_driver.c +++ b/arch/powerpc/kernel/eeh_driver.c @@ -1200,6 +1200,17 @@ void eeh_handle_special_event(void) eeh_pe_state_mark(pe, EEH_PE_RECOVERING); eeh_handle_normal_event(pe); } else { + eeh_for_each_pe(pe, tmp_pe) + eeh_pe_for_each_dev(tmp_pe, edev, tmp_edev) + edev->mode &= ~EEH_DEV_NO_HANDLER; + + /* Notify all devices to be down */ + eeh_pe_state_clear(pe, EEH_PE_PRI_BUS, true); + eeh_set_channel_state(pe, pci_channel_io_perm_failure); + eeh_pe_report( + "error_detected(permanent failure)", pe, + eeh_report_failure, NULL); + pci_lock_rescan_remove(); list_for_each_entry(hose, &hose_list, list_node) { phb_pe = eeh_phb_pe_get(hose); @@ -1208,16 +1219,6 @@ void eeh_handle_special_event(void) (phb_pe->state & EEH_PE_RECOVERING)) continue;
- eeh_for_each_pe(pe, tmp_pe) - eeh_pe_for_each_dev(tmp_pe, edev, tmp_edev) - edev->mode &= ~EEH_DEV_NO_HANDLER; - - /* Notify all devices to be down */ - eeh_pe_state_clear(pe, EEH_PE_PRI_BUS, true); - eeh_set_channel_state(pe, pci_channel_io_perm_failure); - eeh_pe_report( - "error_detected(permanent failure)", pe, - eeh_report_failure, NULL); bus = eeh_pe_bus_get(phb_pe); if (!bus) { pr_err("%s: Cannot find PCI bus for "