[PATCH part5 3/7] ACPI, PCI: Protect global lists in drivers/acpi/pci_root.c

Yinghai Lu
2012-09-02T21:56:32Z

From: Jiang Liu <jiang.liu@huawei.com>

There are two global lists inf file drivers/acpi/pci_root.c.
One is for registered acpi_pci_drivers, the other is for
enumerated ACPI PCI root bridge objects. These two global
lists may change dynamically when registering/deregistering
acpi_pci_drivers or adding/removing ACPI PCI root bridge
objects. So protect them by mutex lock and RCU list.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
drivers/acpi/pci_root.c | 87 ++++++++++++++++++++++++++++------------------
1 files changed, 53 insertions(+), 34 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 9ba516b..f3402df 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -27,7 +27,8 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/rculist.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/pci.h>
@@ -71,6 +72,8 @@ static struct acpi_driver acpi_pci_root_driver = {
},
};

+/* Lock to protect both acpi_pci_roots and acpi_pci_drivers lists */
+static DEFINE_MUTEX(acpi_pci_root_lock);
static LIST_HEAD(acpi_pci_roots);
static LIST_HEAD(acpi_pci_drivers);

@@ -81,47 +84,48 @@ int acpi_pci_register_driver(struct acpi_pci_driver *driver)
int n = 0;
struct acpi_pci_root *root;

+ mutex_lock(&acpi_pci_root_lock);
list_add_tail(&driver->node, &acpi_pci_drivers);
-
- if (!driver->add)
- return 0;
-
- list_for_each_entry(root, &acpi_pci_roots, node) {
- driver->add(root->device->handle);
- n++;
- }
+ if (driver->add)
+ list_for_each_entry_rcu(root, &acpi_pci_roots, node) {
+ driver->add(root->device->handle);
+ n++;
+ }
+ mutex_unlock(&acpi_pci_root_lock);

return n;
}
-
EXPORT_SYMBOL(acpi_pci_register_driver);

void acpi_pci_unregister_driver(struct acpi_pci_driver *driver)
{
struct acpi_pci_root *root;

+ mutex_lock(&acpi_pci_root_lock);
list_del(&driver->node);
-
- if (!driver->remove)
- return;
-
- list_for_each_entry(root, &acpi_pci_roots, node)
- driver->remove(root->device->handle);
+ if (driver->remove)
+ list_for_each_entry_rcu(root, &acpi_pci_roots, node)
+ driver->remove(root->device->handle);
+ mutex_unlock(&acpi_pci_root_lock);
}
-
EXPORT_SYMBOL(acpi_pci_unregister_driver);

acpi_handle acpi_get_pci_rootbridge_handle(unsigned int seg, unsigned int bus)
{
struct acpi_pci_root *root;
+ struct acpi_handle *handle = NULL;

- list_for_each_entry(root, &acpi_pci_roots, node)
+ rcu_read_lock();
+ list_for_each_entry_rcu(root, &acpi_pci_roots, node)
if ((root->segment == (u16) seg) &&
- (root->secondary.start == (u16) bus))
- return root->device->handle;
- return NULL;
-}
+ (root->secondary.start == (u16) bus)) {
+ handle = root->device->handle;
+ break;
+ }
+ rcu_read_unlock();

+ return handle;
+}
EXPORT_SYMBOL_GPL(acpi_get_pci_rootbridge_handle);

/**
@@ -268,10 +272,15 @@ struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
{
struct acpi_pci_root *root;

- list_for_each_entry(root, &acpi_pci_roots, node) {
- if (root->device->handle == handle)
+ rcu_read_lock();
+ list_for_each_entry_rcu(root, &acpi_pci_roots, node) {
+ if (root->device->handle == handle) {
+ rcu_read_unlock();
return root;
+ }
}
+ rcu_read_unlock();
+
return NULL;
}
EXPORT_SYMBOL_GPL(acpi_pci_find_root);
@@ -459,7 +468,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
printk(KERN_ERR PREFIX "can't evaluate _SEG\n");
result = -ENODEV;
- goto end;
+ goto out_free;
}

/* Check _CRS first, then _BBN. If no _BBN, default to zero. */
@@ -484,7 +493,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
else {
printk(KERN_ERR PREFIX "can't evaluate _BBN\n");
result = -ENODEV;
- goto end;
+ goto out_free;
}
}

@@ -508,8 +517,8 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
* TBD: Need PCI interface for enumeration/configuration of roots.
*/

- /* TBD: Locking */
- list_add_tail(&root->node, &acpi_pci_roots);
+ mutex_lock(&acpi_pci_root_lock);
+ list_add_tail_rcu(&root->node, &acpi_pci_roots);

printk(KERN_INFO PREFIX "%s [%s] (domain %04x %pR)\n",
acpi_device_name(device), acpi_device_bid(device),
@@ -528,7 +537,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
"Bus %04x:%02x not present in PCI namespace\n",
root->segment, (unsigned int)root->secondary.start);
result = -ENODEV;
- goto end;
+ goto out_del_root;
}

/*
@@ -538,7 +547,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
*/
result = acpi_pci_bind_root(device);
if (result)
- goto end;
+ goto out_del_root;

/*
* PCI Routing Table
@@ -614,11 +623,15 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
if (device->wakeup.flags.run_wake)
device_set_run_wake(root->bus->bridge, true);

+ mutex_unlock(&acpi_pci_root_lock);
+
return 0;

-end:
- if (!list_empty(&root->node))
- list_del(&root->node);
+out_del_root:
+ list_del_rcu(&root->node);
+ mutex_unlock(&acpi_pci_root_lock);
+ synchronize_rcu();
+out_free:
kfree(root);
return result;
}
@@ -628,11 +641,13 @@ static int acpi_pci_root_start(struct acpi_device *device)
struct acpi_pci_root *root = acpi_driver_data(device);
struct acpi_pci_driver *driver;

+ mutex_lock(&acpi_pci_root_lock);
list_for_each_entry(driver, &acpi_pci_drivers, node)
if (driver->add)
driver->add(device->handle);

pci_bus_add_devices(root->bus);
+ mutex_unlock(&acpi_pci_root_lock);

return 0;
}
@@ -642,6 +657,8 @@ static int acpi_pci_root_remove(struct acpi_device *device, int type)
struct acpi_pci_root *root = acpi_driver_data(device);
struct acpi_pci_driver *driver;

+ mutex_lock(&acpi_pci_root_lock);
+
list_for_each_entry(driver, &acpi_pci_drivers, node)
if (driver->remove)
driver->remove(root->device->handle);
@@ -661,7 +678,9 @@ static int acpi_pci_root_remove(struct acpi_device *device, int type)
pci_stop_and_remove_bus(root->bus);

out:
- list_del(&root->node);
+ list_del_rcu(&root->node);
+ mutex_unlock(&acpi_pci_root_lock);
+ synchronize_rcu();
kfree(root);

return 0;
--
1.7.7