[PATCH] powerpc/eeh: Fix recursive locking on devices without EEH sensitive driver

[Shivaprasad G Bhat]

The commit 1010b4c012b0 ("powerpc/eeh: Make EEH driver device hotplug
safe") refactored the EEH code such that the pci_rescan_remove_lock is
held at the beginning of eeh_handle_normal_event() and the
eeh_reset_device() is called with that lock being held. Looks like the
commit missed to remove the existing lock/unlock inside eeh_rmv_device()
which is no longer necessary. This is causing the eehd to hang on the
lock which it actually holds when that code path is taken.

[<0>] 0xc00000011c78f870
[<0>] __switch_to+0xfc/0x1a0
[<0>] pci_lock_rescan_remove+0x30/0x44
[<0>] eeh_rmv_device+0x290/0x2e0
[<0>] eeh_pe_dev_traverse+0x80/0x130
[<0>] eeh_reset_device+0xcc/0x23c
[<0>] eeh_handle_normal_event+0x830/0xa80
[<0>] eeh_event_handler+0xf8/0x190
[<0>] kthread+0x194/0x1b0
[<0>] start_kernel_thread+0x14/0x18

The issue is seen for cases where the errors are detected on the PHB
directly AND|OR for devices where the driver error_detected() returns
PCI_ERS_RESULT_NEED_RESET, and driver being not EEH sensitive(i.e no
error handlers like slot_reset(), resume() etc defined).

Fixes: 1010b4c012b0 ("powerpc/eeh: Make EEH driver device hotplug safe")
Signed-off-by: Shivaprasad G Bhat <sbhat at linux.ibm.com>
---
 arch/powerpc/kernel/eeh_driver.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index 028f69158532..d64cce17a4e0 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -533,9 +533,7 @@ static void eeh_rmv_device(struct eeh_dev *edev, void *userdata)
 		if (rmv_data)
 			list_add(&edev->rmv_entry, &rmv_data->removed_vf_list);
 	} else {
-		pci_lock_rescan_remove();
 		pci_stop_and_remove_bus_device(dev);
-		pci_unlock_rescan_remove();
 	}
 }