Patchwork [3.5.yuz,extended,stable] Patch "powerpc/eeh: Lock module while handling EEH event" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Nov. 15, 2012, 5:47 a.m.
Message ID <1352958455-15002-1-git-send-email-herton.krzesinski@canonical.com>
Download mbox | patch
Permalink /patch/199141/
State New
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Comments

Herton Ronaldo Krzesinski - Nov. 15, 2012, 5:47 a.m.
This is a note to let you know that I have just added a patch titled

    powerpc/eeh: Lock module while handling EEH event

to the linux-3.5.y-queue branch of the 3.5.yuz extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.yuz tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

From b56418eb75ad82e1d8599928ab27e9136e39703c Mon Sep 17 00:00:00 2001
From: Gavin Shan <shangw@linux.vnet.ibm.com>
Date: Mon, 17 Sep 2012 04:34:27 +0000
Subject: [PATCH] powerpc/eeh: Lock module while handling EEH event

commit feadf7c0a1a7c08c74bebb4a13b755f8c40e3bbc upstream.

The EEH core is talking with the PCI device driver to determine the
action (purely reset, or PCI device removal). During the period, the
driver might be unloaded and in turn causes kernel crash as follows:

EEH: Detected PCI bus error on PHB#4-PE#10000
EEH: This PCI device has failed 3 times in the last hour
lpfc 0004:01:00.0: 0:2710 PCI channel disable preparing for reset
Unable to handle kernel paging request for data at address 0x00000490
Faulting instruction address: 0xd00000000e682c90
cpu 0x1: Vector: 300 (Data Access) at [c000000fc75ffa20]
    pc: d00000000e682c90: .lpfc_io_error_detected+0x30/0x240 [lpfc]
    lr: d00000000e682c8c: .lpfc_io_error_detected+0x2c/0x240 [lpfc]
    sp: c000000fc75ffca0
   msr: 8000000000009032
   dar: 490
 dsisr: 40000000
  current = 0xc000000fc79b88b0
  paca    = 0xc00000000edb0380	 softe: 0	 irq_happened: 0x00
    pid   = 3386, comm = eehd
enter ? for help
[c000000fc75ffca0] c000000fc75ffd30 (unreliable)
[c000000fc75ffd30] c00000000004fd3c .eeh_report_error+0x7c/0xf0
[c000000fc75ffdc0] c00000000004ee00 .eeh_pe_dev_traverse+0xa0/0x180
[c000000fc75ffe70] c00000000004ffd8 .eeh_handle_event+0x68/0x300
[c000000fc75fff00] c0000000000503a0 .eeh_event_handler+0x130/0x1a0
[c000000fc75fff90] c000000000020138 .kernel_thread+0x54/0x70
1:mon>

The patch increases the reference of the corresponding driver modules
while EEH core does the negotiation with PCI device driver so that the
corresponding driver modules can't be unloaded during the period and
we're safe to refer the callbacks.

Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[ herton: backported for 3.5, adjusted driver assignments, return 0
  instead of NULL, assume dev is not NULL ]
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
 arch/powerpc/platforms/pseries/eeh_driver.c |   95 +++++++++++++++++++++------
 1 file changed, 74 insertions(+), 21 deletions(-)

--
1.7.9.5

Patch

diff --git a/arch/powerpc/platforms/pseries/eeh_driver.c b/arch/powerpc/platforms/pseries/eeh_driver.c
index baf92cd..041e28d 100644
--- a/arch/powerpc/platforms/pseries/eeh_driver.c
+++ b/arch/powerpc/platforms/pseries/eeh_driver.c
@@ -25,6 +25,7 @@ 
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/module.h>
 #include <linux/pci.h>
 #include <asm/eeh.h>
 #include <asm/eeh_event.h>
@@ -47,6 +48,41 @@  static inline const char *eeh_pcid_name(struct pci_dev *pdev)
 	return "";
 }

+/**
+ * eeh_pcid_get - Get the PCI device driver
+ * @pdev: PCI device
+ *
+ * The function is used to retrieve the PCI device driver for
+ * the indicated PCI device. Besides, we will increase the reference
+ * of the PCI device driver to prevent that being unloaded on
+ * the fly. Otherwise, kernel crash would be seen.
+ */
+static inline struct pci_driver *eeh_pcid_get(struct pci_dev *pdev)
+{
+	if (!pdev || !pdev->driver)
+		return NULL;
+
+	if (!try_module_get(pdev->driver->driver.owner))
+		return NULL;
+
+	return pdev->driver;
+}
+
+/**
+ * eeh_pcid_put - Dereference on the PCI device driver
+ * @pdev: PCI device
+ *
+ * The function is called to do dereference on the PCI device
+ * driver of the indicated PCI device.
+ */
+static inline void eeh_pcid_put(struct pci_dev *pdev)
+{
+	if (!pdev || !pdev->driver)
+		return;
+
+	module_put(pdev->driver->driver.owner);
+}
+
 #if 0
 static void print_device_node_tree(struct pci_dn *pdn, int dent)
 {
@@ -126,18 +162,20 @@  static void eeh_enable_irq(struct pci_dev *dev)
 static int eeh_report_error(struct pci_dev *dev, void *userdata)
 {
 	enum pci_ers_result rc, *res = userdata;
-	struct pci_driver *driver = dev->driver;
+	struct pci_driver *driver;

 	dev->error_state = pci_channel_io_frozen;

-	if (!driver)
-		return 0;
+	driver = eeh_pcid_get(dev);
+	if (!driver) return 0;

 	eeh_disable_irq(dev);

 	if (!driver->err_handler ||
-	    !driver->err_handler->error_detected)
+	    !driver->err_handler->error_detected) {
+		eeh_pcid_put(dev);
 		return 0;
+	}

 	rc = driver->err_handler->error_detected(dev, pci_channel_io_frozen);

@@ -145,6 +183,7 @@  static int eeh_report_error(struct pci_dev *dev, void *userdata)
 	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
 	if (*res == PCI_ERS_RESULT_NONE) *res = rc;

+	eeh_pcid_put(dev);
 	return 0;
 }

@@ -160,12 +199,16 @@  static int eeh_report_error(struct pci_dev *dev, void *userdata)
 static int eeh_report_mmio_enabled(struct pci_dev *dev, void *userdata)
 {
 	enum pci_ers_result rc, *res = userdata;
-	struct pci_driver *driver = dev->driver;
+	struct pci_driver *driver;
+
+	driver = eeh_pcid_get(dev);
+	if (!driver) return 0;

-	if (!driver ||
-	    !driver->err_handler ||
-	    !driver->err_handler->mmio_enabled)
+	if (!driver->err_handler ||
+	    !driver->err_handler->mmio_enabled) {
+		eeh_pcid_put(dev);
 		return 0;
+	}

 	rc = driver->err_handler->mmio_enabled(dev);

@@ -173,6 +216,7 @@  static int eeh_report_mmio_enabled(struct pci_dev *dev, void *userdata)
 	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
 	if (*res == PCI_ERS_RESULT_NONE) *res = rc;

+	eeh_pcid_put(dev);
 	return 0;
 }

@@ -189,18 +233,20 @@  static int eeh_report_mmio_enabled(struct pci_dev *dev, void *userdata)
 static int eeh_report_reset(struct pci_dev *dev, void *userdata)
 {
 	enum pci_ers_result rc, *res = userdata;
-	struct pci_driver *driver = dev->driver;
-
-	if (!driver)
-		return 0;
+	struct pci_driver *driver;

 	dev->error_state = pci_channel_io_normal;

+	driver = eeh_pcid_get(dev);
+	if (!driver) return 0;
+
 	eeh_enable_irq(dev);

 	if (!driver->err_handler ||
-	    !driver->err_handler->slot_reset)
+	    !driver->err_handler->slot_reset) {
+		eeh_pcid_put(dev);
 		return 0;
+	}

 	rc = driver->err_handler->slot_reset(dev);
 	if ((*res == PCI_ERS_RESULT_NONE) ||
@@ -208,6 +254,7 @@  static int eeh_report_reset(struct pci_dev *dev, void *userdata)
 	if (*res == PCI_ERS_RESULT_DISCONNECT &&
 	     rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;

+	eeh_pcid_put(dev);
 	return 0;
 }

@@ -222,21 +269,24 @@  static int eeh_report_reset(struct pci_dev *dev, void *userdata)
  */
 static int eeh_report_resume(struct pci_dev *dev, void *userdata)
 {
-	struct pci_driver *driver = dev->driver;
+	struct pci_driver *driver;

 	dev->error_state = pci_channel_io_normal;

-	if (!driver)
-		return 0;
+	driver = eeh_pcid_get(dev);
+	if (!driver) return 0;

 	eeh_enable_irq(dev);

 	if (!driver->err_handler ||
-	    !driver->err_handler->resume)
+	    !driver->err_handler->resume) {
+		eeh_pcid_put(dev);
 		return 0;
+	}

 	driver->err_handler->resume(dev);

+	eeh_pcid_put(dev);
 	return 0;
 }

@@ -250,21 +300,24 @@  static int eeh_report_resume(struct pci_dev *dev, void *userdata)
  */
 static int eeh_report_failure(struct pci_dev *dev, void *userdata)
 {
-	struct pci_driver *driver = dev->driver;
+	struct pci_driver *driver;

 	dev->error_state = pci_channel_io_perm_failure;

-	if (!driver)
-		return 0;
+	driver = eeh_pcid_get(dev);
+	if (!driver) return 0;

 	eeh_disable_irq(dev);

 	if (!driver->err_handler ||
-	    !driver->err_handler->error_detected)
+	    !driver->err_handler->error_detected) {
+		eeh_pcid_put(dev);
 		return 0;
+	}

 	driver->err_handler->error_detected(dev, pci_channel_io_perm_failure);

+	eeh_pcid_put(dev);
 	return 0;
 }