linux-kernel - [PATCH v18 03/11] PCI/DPC: Fix DPC recovery issue in non hotplug case

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Message-Id: <0e6f89cd6b9e4a72293cc90fafe93487d7c2d295.1585000084.git.sathyanarayanan.kuppuswamy@linux.intel.com>
Date:   Mon, 23 Mar 2020 17:26:00 -0700
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, sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: [PATCH v18 03/11] PCI/DPC: Fix DPC recovery issue in non hotplug case

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

If hotplug is supported, during DPC event, hotplug
driver would remove the affected devices and detach
the drivers on DLLSC link down event and will
re-enumerate it once the DPC recovery is handled
and link comes back online (on DLLSC LINK up event).
Hence we don't depend on .mmio_enabled or .slot_reset
callbacks in error recovery handler to restore the
device.

But if hotplug is not supported/enabled, then we need
to let the error recovery handler attempt
the recovery of the devices using slot reset.

So if hotplug is not supported, then instead of
returning PCI_ERS_RESULT_RECOVERED, return
PCI_ERS_RESULT_NEED_RESET.

Also modify the way error recovery handler processes
the recovery value.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
---
 drivers/pci/pcie/dpc.c | 8 ++++++++
 drivers/pci/pcie/err.c | 5 +++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index e06f42f58d3d..0e356ed0d73f 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -13,6 +13,7 @@
 #include <linux/interrupt.h>
 #include <linux/init.h>
 #include <linux/pci.h>
+#include <linux/pci_hotplug.h>
 
 #include "portdrv.h"
 #include "../pci.h"
@@ -144,6 +145,13 @@ static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
 	if (!pcie_wait_for_link(pdev, true))
 		return PCI_ERS_RESULT_DISCONNECT;
 
+	/*
+	 * If hotplug is not supported/enabled then let the device
+	 * recover using slot reset.
+	 */
+	if (!hotplug_is_native(pdev))
+		return PCI_ERS_RESULT_NEED_RESET;
+
 	return PCI_ERS_RESULT_RECOVERED;
 }
 
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 1ac57e9e1e71..6e52591a4722 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -178,7 +178,8 @@ static pci_ers_result_t reset_link(struct pci_dev *dev, u32 service)
 		return PCI_ERS_RESULT_DISCONNECT;
 	}
 
-	if (status != PCI_ERS_RESULT_RECOVERED) {
+	if ((status != PCI_ERS_RESULT_RECOVERED) &&
+	    (status != PCI_ERS_RESULT_NEED_RESET)) {
 		pci_printk(KERN_DEBUG, dev, "link reset at upstream device %s failed\n",
 			pci_name(dev));
 		return PCI_ERS_RESULT_DISCONNECT;
@@ -206,7 +207,7 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state,
 	if (state == pci_channel_io_frozen) {
 		pci_walk_bus(bus, report_frozen_detected, &status);
 		status = reset_link(dev, service);
-		if (status != PCI_ERS_RESULT_RECOVERED)
+		if (status == PCI_ERS_RESULT_DISCONNECT)
 			goto failed;
 	} else {
 		pci_walk_bus(bus, report_normal_detected, &status);
-- 
2.17.1