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Date: Fri, 27 Apr 2012 23:16:44 +0800
From: Jiang Liu <liuj97@...il.com>
To: Yinghai Lu <yinghai@...nel.org>,
Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Don Dutile <ddutile@...hat.com>,
Greg KH <gregkh@...uxfoundation.org>
Cc: Jiang Liu <jiang.liu@...wei.com>,
Keping Chen <chenkeping@...wei.com>,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
Jiang Liu <liuj97@...il.com>
Subject: [PATCH v2 03/19] PCI: replace pci_remove_rescan_mutex with the PCI hotplug lock
From: Jiang Liu <jiang.liu@...wei.com>
Replace pci_remove_rescan_mutex with the PCI hotplug lock, which is used to
globally serialize all PCI hotplug operations.
Signed-off-by: Jiang Liu <liuj97@...il.com>
---
drivers/pci/pci-sysfs.c | 100 +++++++++++++++++++++++++++--------------------
drivers/pci/remove.c | 1 +
2 files changed, 58 insertions(+), 43 deletions(-)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index a55e248..ecf197d 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -283,7 +283,31 @@ msi_bus_store(struct device *dev, struct device_attribute *attr,
}
#ifdef CONFIG_HOTPLUG
-static DEFINE_MUTEX(pci_remove_rescan_mutex);
+/*
+ * Schedule a device callback to avoid deadlock in case of
+ * 1) An attribute method tries to deregister the sysfs file itself
+ * 2) Another thread is trying to remove the sysfs file, which have
+ * already held the PCI hotplug lock by invoking pci_hotplug_enter().
+ */
+static int schedule_hp_callback(struct device *dev,
+ const char *buf, size_t count,
+ void (*func)(struct device *))
+{
+ int ret = 0;
+ unsigned long val;
+
+ if (kstrtoul(buf, 0, &val) < 0)
+ return -EINVAL;
+
+ if (val) {
+ ret = device_schedule_callback(dev, func);
+ if (ret)
+ count = ret;
+ }
+
+ return count;
+}
+
static ssize_t bus_rescan_store(struct bus_type *bus, const char *buf,
size_t count)
{
@@ -294,10 +318,10 @@ static ssize_t bus_rescan_store(struct bus_type *bus, const char *buf,
return -EINVAL;
if (val) {
- mutex_lock(&pci_remove_rescan_mutex);
+ pci_hotplug_enter();
while ((b = pci_find_next_bus(b)) != NULL)
pci_rescan_bus(b);
- mutex_unlock(&pci_remove_rescan_mutex);
+ pci_hotplug_exit();
}
return count;
}
@@ -307,72 +331,62 @@ struct bus_attribute pci_bus_attrs[] = {
__ATTR_NULL
};
-static ssize_t
-dev_rescan_store(struct device *dev, struct device_attribute *attr,
- const char *buf, size_t count)
+static void dev_rescan_callback(struct device *dev)
{
- unsigned long val;
struct pci_dev *pdev = to_pci_dev(dev);
- if (strict_strtoul(buf, 0, &val) < 0)
- return -EINVAL;
-
- if (val) {
- mutex_lock(&pci_remove_rescan_mutex);
+ pci_hotplug_enter();
+ /* Skip if the device has been stopped. */
+ if (pdev->is_added && pdev->bus)
pci_rescan_bus(pdev->bus);
- mutex_unlock(&pci_remove_rescan_mutex);
- }
- return count;
+ pci_hotplug_exit();
+}
+
+static ssize_t
+dev_rescan_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ return schedule_hp_callback(dev, buf, count, dev_rescan_callback);
}
static void remove_callback(struct device *dev)
{
struct pci_dev *pdev = to_pci_dev(dev);
- mutex_lock(&pci_remove_rescan_mutex);
- pci_stop_and_remove_bus_device(pdev);
- mutex_unlock(&pci_remove_rescan_mutex);
+ pci_hotplug_enter();
+ /* Skip if the bus has been removed. */
+ if (pdev->bus_list.next)
+ pci_stop_and_remove_bus_device(pdev);
+ pci_hotplug_exit();
}
static ssize_t
remove_store(struct device *dev, struct device_attribute *dummy,
const char *buf, size_t count)
{
- int ret = 0;
- unsigned long val;
-
- if (strict_strtoul(buf, 0, &val) < 0)
- return -EINVAL;
-
- /* An attribute cannot be unregistered by one of its own methods,
- * so we have to use this roundabout approach.
- */
- if (val)
- ret = device_schedule_callback(dev, remove_callback);
- if (ret)
- count = ret;
- return count;
+ return schedule_hp_callback(dev, buf, count, remove_callback);
}
-static ssize_t
-dev_bus_rescan_store(struct device *dev, struct device_attribute *attr,
- const char *buf, size_t count)
+static void dev_bus_rescan_callback(struct device *dev)
{
- unsigned long val;
struct pci_bus *bus = to_pci_bus(dev);
- if (strict_strtoul(buf, 0, &val) < 0)
- return -EINVAL;
-
- if (val) {
- mutex_lock(&pci_remove_rescan_mutex);
+ pci_hotplug_enter();
+ /* Skip if the bus has been stopped. */
+ if (bus->is_added) {
if (!pci_is_root_bus(bus) && list_empty(&bus->devices))
pci_rescan_bus_bridge_resize(bus->self);
else
pci_rescan_bus(bus);
- mutex_unlock(&pci_remove_rescan_mutex);
}
- return count;
+ pci_hotplug_exit();
+}
+
+static ssize_t
+dev_bus_rescan_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ return schedule_hp_callback(dev, buf, count, dev_bus_rescan_callback);
}
#endif
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index fd77e2b..0b4342b 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -72,6 +72,7 @@ void pci_remove_bus(struct pci_bus *pci_bus)
if (!pci_bus->is_added)
return;
+ pci_bus->is_added = 0;
pci_remove_legacy_files(pci_bus);
device_unregister(&pci_bus->dev);
}
--
1.7.5.4
--
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