linux-kernel - [PATCH v1 1/1] PCI/ERR: don't clobber status after reset

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Message-Id: <20201009025251.2360659-1-hedi.berriche@hpe.com>
Date:   Fri,  9 Oct 2020 03:52:51 +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>,
        Keith Busch <keith.busch@...el.com>,
        Joerg Roedel <jroedel@...e.com>, stable@...nel.org
Subject: [PATCH v1 1/1] PCI/ERR: don't clobber status after reset_link()

Commit 6d2c89441571 ("PCI/ERR: Update error status after reset_link()")
changed pcie_do_recovery() so that status is updated with the return
value from reset_link(); this was to fix the problem where we would
wrongly report recovery failure, despite a successful reset_link(),
whenever the initial error status is PCI_ERS_RESULT_DISCONNECT or
PCI_ERS_RESULT_NO_AER_DRIVER.

Unfortunately this breaks the flow of pcie_do_recovery() as it prevents
the actions needed when the initial error is PCI_ERS_RESULT_CAN_RECOVER
or PCI_ERS_RESULT_NEED_RESET from taking place which causes error
recovery to fail.

Don't clobber status after reset_link() to restore the intended flow in
pcie_do_recovery().

Fix the original problem by saving the return value from reset_link()
and use it later on to decide whether error recovery should be deemed
successful in the scenarios where the initial error status is
PCI_ERS_RESULT_{DISCONNECT,NO_AER_DRIVER}.

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: Keith Busch <keith.busch@...el.com>
Cc: Joerg Roedel <jroedel@...e.com>

Cc: stable@...nel.org # v5.7+
---
 drivers/pci/pcie/err.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index c543f419d8f9..dbd0b56bd6c1 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -150,7 +150,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
 			pci_channel_state_t state,
 			pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
 {
-	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
+	pci_ers_result_t post_reset_status, status = PCI_ERS_RESULT_CAN_RECOVER;
 	struct pci_bus *bus;
 
 	/*
@@ -165,8 +165,8 @@ 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) {
+		post_reset_status = reset_link(dev);
+		if (post_reset_status != PCI_ERS_RESULT_RECOVERED) {
 			pci_warn(dev, "link reset failed\n");
 			goto failed;
 		}
@@ -174,6 +174,13 @@ 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) &&
+	     post_reset_status == PCI_ERS_RESULT_RECOVERED) {
+		/* error recovery succeeded thanks to reset_link() */
+		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