linux-kernel - [PATCH 5.8 034/148] s390/pci: ignore stale configuration request event

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Date:   Mon, 24 Aug 2020 10:28:52 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Shalini Chellathurai Saroja <shalini@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>
Subject: [PATCH 5.8 034/148] s390/pci: ignore stale configuration request event

From: Niklas Schnelle <schnelle@...ux.ibm.com>

commit b76fee1bc56c31a9d2a49592810eba30cc06d61a upstream.

A configuration request event may be stale, that is the event
may reference a zdev which was already configured.
This can happen when a hotplug happens during boot such that
the device is discovered and configured in the initial clp_list_pci(),
then after initialization we enable events and process
the original configuration request which additionally still contains
the old disabled function handle leading to a failure during device
enablement and subsequent I/O lockout.

Fix this by restoring the check that the device to be configured is in
standby which was removed in commit f606b3ef47c9 ("s390/pci: adapt events
for zbus").

This check does not need serialization as we only enable the events after
zPCI has fully initialized, which includes the initial clp_list_pci(),
rescan only does updates and events are serialized with respect to each
other.

Fixes: f606b3ef47c9 ("s390/pci: adapt events for zbus")
Cc: <stable@...r.kernel.org> # 5.8
Reported-by: Shalini Chellathurai Saroja <shalini@...ux.ibm.com>
Tested-by: Shalini Chellathurai Saroja <shalini@...ux.ibm.com>
Acked-by: Pierre Morel <pmorel@...ux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/s390/pci/pci_event.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/s390/pci/pci_event.c
+++ b/arch/s390/pci/pci_event.c
@@ -92,6 +92,9 @@ static void __zpci_event_availability(st
 			ret = clp_add_pci_device(ccdf->fid, ccdf->fh, 1);
 			break;
 		}
+		/* the configuration request may be stale */
+		if (zdev->state != ZPCI_FN_STATE_STANDBY)
+			break;
 		zdev->fh = ccdf->fh;
 		zdev->state = ZPCI_FN_STATE_CONFIGURED;
 		ret = zpci_enable_device(zdev);