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authorHari Vyas <hari.vyas@broadcom.com>2018-07-03 14:35:41 +0530
committerBjorn Helgaas <bhelgaas@google.com>2018-07-31 11:27:54 -0500
commit44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76 (patch)
tree46ed284871234e825bc3211dd5bf0d960b7c3cda /drivers/pci
parenta54e43f993f8ec2f063b616a0e4d2b09e08d78a5 (diff)
PCI: Fix is_added/is_busmaster race condition
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>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/bus.c6
-rw-r--r--drivers/pci/hotplug/acpiphp_glue.c2
-rw-r--r--drivers/pci/pci.h11
-rw-r--r--drivers/pci/probe.c4
-rw-r--r--drivers/pci/remove.c5
5 files changed, 20 insertions, 8 deletions
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 35b7fc87eac5..5cb40b2518f9 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -330,7 +330,7 @@ void pci_bus_add_device(struct pci_dev *dev)
return;
}
- dev->is_added = 1;
+ pci_dev_assign_added(dev, true);
}
EXPORT_SYMBOL_GPL(pci_bus_add_device);
@@ -347,14 +347,14 @@ void pci_bus_add_devices(const struct pci_bus *bus)
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)
diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 3a17b290df5d..ef0b1b6ba86f 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -509,7 +509,7 @@ static void enable_slot(struct acpiphp_slot *slot)
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;
}
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 882f1f9596df..08817253c8a2 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -288,6 +288,7 @@ 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)
{
@@ -300,6 +301,16 @@ static inline bool pci_dev_is_disconnected(const struct pci_dev *dev)
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
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index ac876e32de4b..611adcd9c169 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2433,13 +2433,13 @@ int pci_scan_slot(struct pci_bus *bus, int devfn)
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;
}
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 6f072eae4f7a..5e3d0dced2b8 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -19,11 +19,12 @@ static void pci_stop_dev(struct pci_dev *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)