linux-kernel - [PATCH v2 1/1] PCI/ERR: don't clobber status after reset

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Date:   Sat, 10 Oct 2020 01:09:16 +0100
From:   Hedi Berriche <hedi.berriche@....com>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hedi Berriche <hedi.berriche@....com>,
        Russ Anderson <rja@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Joerg Roedel <jroedel@...e.com>, stable@...nel.org
Subject: [PATCH v2 1/1] PCI/ERR: don't clobber status after reset_link()

Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
broke pcie_do_recovery(): updating status after reset_link() has the ill
side effect of causing recovery to fail if the error status is
PCI_ERS_RESULT_CAN_RECOVER or PCI_ERS_RESULT_NEED_RESET as the following
code will *never* run in the case of a successful reset_link()

   177         if (status == PCI_ERS_RESULT_CAN_RECOVER) {
   ...
   181         }

   183         if (status == PCI_ERS_RESULT_NEED_RESET) {
   ...
   192         }

For instance in the case of PCI_ERS_RESULT_NEED_RESET we end up not
calling ->slot_reset() (because we skip report_slot_reset()) thus
breaking driver (re)initialisation.

Don't clobber status after reset_link(), use a boolean instead to track
the outcome of reset_link().

Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
Signed-off-by: Hedi Berriche <hedi.berriche@....com>
Cc: Russ Anderson <rja@....com>
Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: Joerg Roedel <jroedel@...e.com>

Cc: stable@...nel.org # v5.7+
---
 drivers/pci/pcie/err.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index c543f419d8f9..b4bfa87fc49d 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -152,6 +152,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 {
 	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
 	struct pci_bus *bus;
+	bool reset_failed = false;
 
 	/*
 	 * Error recovery runs on all subordinates of the first downstream port.
@@ -165,8 +166,8 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 	pci_dbg(dev, "broadcast error_detected message\n");
 	if (state == pci_channel_io_frozen) {
 		pci_walk_bus(bus, report_frozen_detected, &status);
-		status = reset_link(dev);
-		if (status != PCI_ERS_RESULT_RECOVERED) {
+		reset_failed = (reset_link(dev) != PCI_ERS_RESULT_RECOVERED);
+		if (reset_failed) {
 			pci_warn(dev, "link reset failed\n");
 			goto failed;
 		}
@@ -174,6 +175,12 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 		pci_walk_bus(bus, report_normal_detected, &status);
 	}
 
+	if ((status == PCI_ERS_RESULT_DISCONNECT ||
+	     status == PCI_ERS_RESULT_NO_AER_DRIVER) &&
+	     !reset_failed) {
+		status = PCI_ERS_RESULT_RECOVERED;
+	}
+
 	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
 		status = PCI_ERS_RESULT_RECOVERED;
 		pci_dbg(dev, "broadcast mmio_enabled message\n");
-- 
2.28.0