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powerpc/eeh: Fix deadlock handling dead PHB 

commit d4f194ed9e 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: 2e25505147 ("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.1581051445.git.sbobroff@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Sam Bobroff 2020-02-07 15:57:31 +11:00 committed by Greg Kroah-Hartman
parent 9e1fab4450
commit a03b3cea86
1 changed files with 11 additions and 10 deletions
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21
arch/powerpc/kernel/eeh_driver.c
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@ -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 "