powerpc/eeh: Clear stale EEH_DEV_NO_HANDLER flag

The EEH_DEV_NO_HANDLER flag is used by the EEH system to prevent the
use of driver callbacks in drivers that have been bound part way
through the recovery process. This is necessary to prevent later stage
handlers from being called when the earlier stage handlers haven't,
which can be confusing for drivers.

However, the flag is set for all devices that are added after boot
time and only cleared at the end of the EEH recovery process. This
results in hot plugged devices erroneously having the flag set during
the first recovery after they are added (causing their driver's
handlers to be incorrectly ignored).

To remedy this, clear the flag at the beginning of recovery
processing. The flag is still cleared at the end of recovery
processing, although it is no longer really necessary.

Also clear the flag during eeh_handle_special_event(), for the same
reasons.
Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b8ca5629d27de74c957d4f4b250177d1b6fc4bbd.1565930772.git.sbobroff@linux.ibm.com

arch/powerpc/kernel/eeh_driver.c

@@ -793,6 +793,10 @@ void eeh_handle_normal_event(struct eeh_pe *pe)
 		result = PCI_ERS_RESULT_DISCONNECT;
 	}
 
+	eeh_for_each_pe(pe, tmp_pe)
+		eeh_pe_for_each_dev(tmp_pe, edev, tmp)
+			edev->mode &= ~EEH_DEV_NO_HANDLER;
+
 	/* Walk the various device drivers attached to this slot through
 	 * a reset sequence, giving each an opportunity to do what it needs
 	 * to accomplish the reset.  Each child gets a report of the
@@ -981,7 +985,8 @@ void eeh_handle_normal_event(struct eeh_pe *pe)
  */
 void eeh_handle_special_event(void)
 {
-	struct eeh_pe *pe, *phb_pe;
+	struct eeh_pe *pe, *phb_pe, *tmp_pe;
+	struct eeh_dev *edev, *tmp_edev;
 	struct pci_bus *bus;
 	struct pci_controller *hose;
 	unsigned long flags;
@@ -1050,6 +1055,10 @@ 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);