From 44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76 Mon Sep 17 00:00:00 2001
From: Hari Vyas <hari.vyas@broadcom.com>
Date: Tue, 3 Jul 2018 14:35:41 +0530
Subject: [PATCH] PCI: Fix is_added/is_busmaster race condition
Git-commit: 44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76
Patch-mainline: v4.18
References: FATE#326303
When a PCI device is detected, pdev->is_added is set to 1 and proc and
sysfs entries are created.
When the device is removed, pdev->is_added is checked for one and then
device is detached with clearing of proc and sys entries and at end,
pdev->is_added is set to 0.
is_added and is_busmaster are bit fields in pci_dev structure sharing same
memory location.
A strange issue was observed with multiple removal and rescan of a PCIe
NVMe device using sysfs commands where is_added flag was observed as zero
instead of one while removing device and proc,sys entries are not cleared.
This causes issue in later device addition with warning message
"proc_dir_entry" already registered.
Debugging revealed a race condition between the PCI core setting the
is_added bit in pci_bus_add_device() and the NVMe driver reset work-queue
setting the is_busmaster bit in pci_set_master(). As these fields are not
handled atomically, that clears the is_added bit.
Move the is_added bit to a separate private flag variable and use atomic
functions to set and retrieve the device addition state. This avoids the
race because is_added no longer shares a memory location with is_busmaster.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=200283
Signed-off-by: Hari Vyas <hari.vyas@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
arch/powerpc/kernel/pci-common.c | 4 +++-
arch/powerpc/platforms/powernv/pci-ioda.c | 3 ++-
arch/powerpc/platforms/pseries/setup.c | 3 ++-
drivers/pci/bus.c | 6 +++---
drivers/pci/hotplug/acpiphp_glue.c | 2 +-
drivers/pci/pci.h | 11 +++++++++++
drivers/pci/probe.c | 4 ++--
drivers/pci/remove.c | 5 +++--
include/linux/pci.h | 1 -
9 files changed, 27 insertions(+), 12 deletions(-)
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -42,6 +42,8 @@
#include <asm/ppc-pci.h>
#include <asm/eeh.h>
+#include "../../../drivers/pci/pci.h"
+
/* hose_spinlock protects accesses to the the phb_bitmap. */
static DEFINE_SPINLOCK(hose_spinlock);
LIST_HEAD(hose_list);
@@ -1106,7 +1108,7 @@ void pcibios_setup_bus_devices(struct pc
/* Cardbus can call us to add new devices to a bus, so ignore
* those who are already fully discovered
*/
- if (dev->is_added)
+ if (pci_dev_is_added(dev))
continue;
pcibios_setup_device(dev);
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -46,6 +46,7 @@
#include "powernv.h"
#include "pci.h"
+#include "../../../../drivers/pci/pci.h"
#define PNV_IODA1_M64_NUM 16 /* Number of M64 BARs */
#define PNV_IODA1_M64_SEGS 8 /* Segments per M64 BAR */
@@ -2934,7 +2935,7 @@ static void pnv_pci_ioda_fixup_iov_resou
struct pci_dn *pdn;
int mul, total_vfs;
- if (!pdev->is_physfn || pdev->is_added)
+ if (!pdev->is_physfn || pci_dev_is_added(pdev))
return;
pdn = pci_get_pdn(pdev);
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -71,6 +71,7 @@
#include <asm/security_features.h>
#include "pseries.h"
+#include "../../../../drivers/pci/pci.h"
int CMO_PrPSP = -1;
int CMO_SecPSP = -1;
@@ -664,7 +665,7 @@ static void pseries_pci_fixup_iov_resour
const int *indexes;
struct device_node *dn = pci_device_to_OF_node(pdev);
- if (!pdev->is_physfn || pdev->is_added)
+ if (!pdev->is_physfn || pci_dev_is_added(pdev))
return;
/*Firmware must support open sriov otherwise dont configure*/
indexes = of_get_property(dn, "ibm,open-sriov-vf-bar-info", NULL);
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -331,7 +331,7 @@ void pci_bus_add_device(struct pci_dev *
return;
}
- dev->is_added = 1;
+ pci_dev_assign_added(dev, true);
}
EXPORT_SYMBOL_GPL(pci_bus_add_device);
@@ -348,14 +348,14 @@ void pci_bus_add_devices(const struct pc
list_for_each_entry(dev, &bus->devices, bus_list) {
/* Skip already-added devices */
- if (dev->is_added)
+ if (pci_dev_is_added(dev))
continue;
pci_bus_add_device(dev);
}
list_for_each_entry(dev, &bus->devices, bus_list) {
/* Skip if device attach failed */
- if (!dev->is_added)
+ if (!pci_dev_is_added(dev))
continue;
child = dev->subordinate;
if (child)
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -523,7 +523,7 @@ static void enable_slot(struct acpiphp_s
list_for_each_entry(dev, &bus->devices, bus_list) {
/* Assume that newly added devices are powered on already. */
- if (!dev->is_added)
+ if (!pci_dev_is_added(dev))
dev->current_state = PCI_D0;
}
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -280,6 +280,7 @@ struct pci_sriov {
/* pci_dev priv_flags */
#define PCI_DEV_DISCONNECTED 0
+#define PCI_DEV_ADDED 1
static inline int pci_dev_set_disconnected(struct pci_dev *dev, void *unused)
{
@@ -292,6 +293,16 @@ static inline bool pci_dev_is_disconnect
return test_bit(PCI_DEV_DISCONNECTED, &dev->priv_flags);
}
+static inline void pci_dev_assign_added(struct pci_dev *dev, bool added)
+{
+ assign_bit(PCI_DEV_ADDED, &dev->priv_flags, added);
+}
+
+static inline bool pci_dev_is_added(const struct pci_dev *dev)
+{
+ return test_bit(PCI_DEV_ADDED, &dev->priv_flags);
+}
+
#ifdef CONFIG_PCI_ATS
void pci_restore_ats_state(struct pci_dev *dev);
#else
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2186,13 +2186,13 @@ int pci_scan_slot(struct pci_bus *bus, i
dev = pci_scan_single_device(bus, devfn);
if (!dev)
return 0;
- if (!dev->is_added)
+ if (!pci_dev_is_added(dev))
nr++;
for (fn = next_fn(bus, dev, 0); fn > 0; fn = next_fn(bus, dev, fn)) {
dev = pci_scan_single_device(bus, devfn + fn);
if (dev) {
- if (!dev->is_added)
+ if (!pci_dev_is_added(dev))
nr++;
dev->multifunction = 1;
}
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -18,11 +18,12 @@ static void pci_stop_dev(struct pci_dev
{
pci_pme_active(dev, false);
- if (dev->is_added) {
+ if (pci_dev_is_added(dev)) {
device_release_driver(&dev->dev);
pci_proc_detach_device(dev);
pci_remove_sysfs_dev_files(dev);
- dev->is_added = 0;
+
+ pci_dev_assign_added(dev, false);
}
if (dev->bus->self)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -352,7 +352,6 @@ struct pci_dev {
unsigned int transparent:1; /* Subtractive decode PCI bridge */
unsigned int multifunction:1;/* Part of multi-function device */
/* keep track of device state */
- unsigned int is_added:1;
unsigned int is_busmaster:1; /* device is busmaster */
unsigned int no_msi:1; /* device may not use msi */
unsigned int no_64bit_msi:1; /* device may only use 32-bit MSIs */