linux-kernel - [PATCH v16 1/9] PCI/ERR: Update error status after reset

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Message-Id: <15e702a33cc27314f9d43a06ccb408086a229cef.1582850766.git.sathyanarayanan.kuppuswamy@linux.intel.com>
Date:   Thu, 27 Feb 2020 16:59:43 -0800
From:   sathyanarayanan.kuppuswamy@...ux.intel.com
To:     bhelgaas@...gle.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        ashok.raj@...el.com,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Keith Busch <keith.busch@...el.com>
Subject: [PATCH v16 1/9] PCI/ERR: Update error status after reset_link()

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>

Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") uses
reset_link() to recover from fatal errors. But during fatal error
recovery, if the initial value of error status is
PCI_ERS_RESULT_DISCONNECT or PCI_ERS_RESULT_NO_AER_DRIVER then
even after successful recovery (using reset_link()) pcie_do_recovery()
will report the recovery result as failure. So update the status of
error after reset_link().

You can reproduce this issue by triggering a SW DPC using "DPC
Software Trigger" bit in "DPC Control Register". You should see recovery
failed dmesg log as below.

[  164.659982] pcieport 0000:00:16.0: DPC: containment event,
status:0x1f27 source:0x0000
[  164.659989] pcieport 0000:00:16.0: DPC: software trigger detected
[  164.659994] pci 0000:04:00.0: AER: can't recover (no error_detected
callback)
[  164.794300] pcieport 0000:00:16.0: AER: device recovery failed

Fixes: bdb5ac85777d ("PCI/ERR: Handle fatal error recovery")
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: Keith Busch <keith.busch@...el.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Acked-by: Keith Busch <keith.busch@...el.com>
---
 drivers/pci/pcie/err.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 01dfc8bb7ca0..eefefe03857a 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -208,9 +208,11 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state,
 	else
 		pci_walk_bus(bus, report_normal_detected, &status);
 
-	if (state == pci_channel_io_frozen &&
-	    reset_link(dev, service) != PCI_ERS_RESULT_RECOVERED)
-		goto failed;
+	if (state == pci_channel_io_frozen) {
+		status = reset_link(dev, service);
+		if (status != PCI_ERS_RESULT_RECOVERED)
+			goto failed;
+	}
 
 	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
 		status = PCI_ERS_RESULT_RECOVERED;
-- 
2.21.0