[PATCH 0/3] Enhance pci_root.c to better support PCI root bus hotplug

[PATCH 0/3] Enhance pci_root.c to better support PCI root bus hotplug

[Jiang Liu]

This series of patches is based on Yinghai's work on PCI root bus hotplug,
which enhance the pci_root.c to better support PCI root bus hotplug.
It applies to
	93c6c6b PCI: Add /sys/bus/pci/rescan_root
at
	git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-pci-root-bus-hotplug

Jiang Liu (3):
  ACPI,PCI: Notify acpi_pci_drivers when hot-plugging PCI root bridges
  ACPI,PCI: protect global lists in drivers/acpi/pci_root.c
  ACPI,PCI: Use normal list for struct acpi_pci_driver

 drivers/acpi/pci_root.c |  111 +++++++++++++++++++++++++++--------------------
 include/linux/acpi.h    |    2 +-
 2 files changed, 65 insertions(+), 48 deletions(-)

-- 
1.7.5.4

[PATCH 1/3] ACPI,PCI: Use normal list for struct acpi_pci_driver

[Jiang Liu]

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

Use normal list for struct acpi_pci_driver to simplify code.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 drivers/acpi/pci_root.c |   16 +++-------------
 include/linux/acpi.h    |    2 +-
 2 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index b38e347..c2d2b7b 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -72,8 +72,8 @@ static struct acpi_driver acpi_pci_root_driver = {
 };
 
 static LIST_HEAD(acpi_pci_roots);
+static LIST_HEAD(acpi_pci_drivers);
 
-static struct acpi_pci_driver *sub_driver;
 static DEFINE_MUTEX(osc_lock);
 
 int acpi_pci_register_driver(struct acpi_pci_driver *driver)
@@ -81,10 +81,7 @@ int acpi_pci_register_driver(struct acpi_pci_driver *driver)
 	int n = 0;
 	struct acpi_pci_root *root;
 
-	struct acpi_pci_driver **pptr = &sub_driver;
-	while (*pptr)
-		pptr = &(*pptr)->next;
-	*pptr = driver;
+	list_add_tail(&driver->node, &acpi_pci_drivers);
 
 	if (!driver->add)
 		return 0;
@@ -103,14 +100,7 @@ void acpi_pci_unregister_driver(struct acpi_pci_driver *driver)
 {
 	struct acpi_pci_root *root;
 
-	struct acpi_pci_driver **pptr = &sub_driver;
-	while (*pptr) {
-		if (*pptr == driver)
-			break;
-		pptr = &(*pptr)->next;
-	}
-	BUG_ON(!*pptr);
-	*pptr = (*pptr)->next;
+	list_del(&driver->node);
 
 	if (!driver->remove)
 		return;
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 3f96866..efcc6c4 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -138,7 +138,7 @@ void acpi_penalize_isa_irq(int irq, int active);
 void acpi_pci_irq_disable (struct pci_dev *dev);
 
 struct acpi_pci_driver {
-	struct acpi_pci_driver *next;
+	struct list_head node;
 	int (*add)(acpi_handle handle);
 	void (*remove)(acpi_handle handle);
 };
-- 
1.7.5.4

[PATCH 2/3] ACPI,PCI: Notify acpi_pci_drivers when hot-plugging PCI root bridges

[Jiang Liu]

From: Jiang Liu <liuj97@gmail.com>

When hot-plugging PCI root bridge, acpi_pci_drivers' add()/remove()
methods should be invoked to notify registered drivers.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 drivers/acpi/pci_root.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index c2d2b7b..ff73357 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -445,6 +445,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	acpi_status status;
 	int result;
 	struct acpi_pci_root *root;
+	struct acpi_pci_driver *driver;
 	acpi_handle handle;
 	struct acpi_device *child;
 	u32 flags, base_flags;
@@ -612,6 +613,10 @@ 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);
 
+	list_for_each_entry(driver, &acpi_pci_drivers, node)
+		if (driver->add)
+			driver->add(device->handle);
+
 	return 0;
 
 end:
@@ -632,6 +637,11 @@ static int acpi_pci_root_start(struct acpi_device *device)
 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;
+
+	list_for_each_entry(driver, &acpi_pci_drivers, node)
+		if (driver->remove)
+			driver->remove(root->device->handle);
 
 	/* that root bus could be removed already */
 	if (!pci_find_bus(root->segment, root->secondary.start)) {
-- 
1.7.5.4

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

[Jiang Liu]

From: Jiang Liu <liuj97@gmail.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>
---
 drivers/acpi/pci_root.c |   85 ++++++++++++++++++++++++++++-------------------
 1 files changed, 51 insertions(+), 34 deletions(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index ff73357..24afd66 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);
@@ -460,7 +469,7 @@ 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. */
@@ -485,7 +494,7 @@ 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;
 		}
 	}
 
@@ -507,8 +516,8 @@ 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),
@@ -527,7 +536,7 @@ 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;
 	}
 
 	/*
@@ -537,7 +546,7 @@ 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
@@ -617,11 +626,15 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 		if (driver->add)
 			driver->add(device->handle);
 
+	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;
 }
@@ -639,6 +652,8 @@ 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);
@@ -658,7 +673,9 @@ 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;
-- 
1.7.5.4

Re: [PATCH 2/3] ACPI,PCI: Notify acpi_pci_drivers when hot-plugging PCI root bridges

[Yinghai Lu]

On Wed, Mar 21, 2012 at 9:22 AM, Jiang Liu <liuj97@gmail.com> wrote:
> From: Jiang Liu <liuj97@gmail.com>
>
> When hot-plugging PCI root bridge, acpi_pci_drivers' add()/remove()
> methods should be invoked to notify registered drivers.
>
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> ---
>  drivers/acpi/pci_root.c |   10 ++++++++++
>  1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index c2d2b7b..ff73357 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -445,6 +445,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
>        acpi_status status;
>        int result;
>        struct acpi_pci_root *root;
> +       struct acpi_pci_driver *driver;
>        acpi_handle handle;
>        struct acpi_device *child;
>        u32 flags, base_flags;
> @@ -612,6 +613,10 @@ 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);
>
> +       list_for_each_entry(driver, &acpi_pci_drivers, node)
> +               if (driver->add)
> +                       driver->add(device->handle);
> +
>        return 0;

if those calling is with acpi_pci_root_start() instead of acpi_pci_root_add()

Do you still need patches 3?

Yinghai

Re: [PATCH 2/3] ACPI,PCI: Notify acpi_pci_drivers when hot-plugging PCI root bridges

[Yinghai Lu]

On Wed, Mar 21, 2012 at 10:04 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Wed, Mar 21, 2012 at 9:22 AM, Jiang Liu <liuj97@gmail.com> wrote:
>> From: Jiang Liu <liuj97@gmail.com>
>>
>> When hot-plugging PCI root bridge, acpi_pci_drivers' add()/remove()
>> methods should be invoked to notify registered drivers.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
>> ---
>>  drivers/acpi/pci_root.c |   10 ++++++++++
>>  1 files changed, 10 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index c2d2b7b..ff73357 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -445,6 +445,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
>>        acpi_status status;
>>        int result;
>>        struct acpi_pci_root *root;
>> +       struct acpi_pci_driver *driver;
>>        acpi_handle handle;
>>        struct acpi_device *child;
>>        u32 flags, base_flags;
>> @@ -612,6 +613,10 @@ 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);
>>
>> +       list_for_each_entry(driver, &acpi_pci_drivers, node)
>> +               if (driver->add)
>> +                       driver->add(device->handle);
>> +
>>        return 0;
>
> if those calling is with acpi_pci_root_start() instead of acpi_pci_root_add()
>

ok, i put those three in my patcheset.

only change is moving that ->add calling to acpi_pci_root_start.

Yinghai

Re: [PATCH 2/3] ACPI,PCI: Notify acpi_pci_drivers when hot-plugging PCI root bridges

[Jiang Liu]

On 2012-3-22 1:04, Yinghai Lu wrote:
> On Wed, Mar 21, 2012 at 9:22 AM, Jiang Liu<liuj97@gmail.com>  wrote:
>> From: Jiang Liu<liuj97@gmail.com>
>>
>> When hot-plugging PCI root bridge, acpi_pci_drivers' add()/remove()
>> methods should be invoked to notify registered drivers.
>>
>> Signed-off-by: Jiang Liu<jiang.liu@huawei.com>
>> ---
>>   drivers/acpi/pci_root.c |   10 ++++++++++
>>   1 files changed, 10 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index c2d2b7b..ff73357 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -445,6 +445,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
>>         acpi_status status;
>>         int result;
>>         struct acpi_pci_root *root;
>> +       struct acpi_pci_driver *driver;
>>         acpi_handle handle;
>>         struct acpi_device *child;
>>         u32 flags, base_flags;
>> @@ -612,6 +613,10 @@ 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);
>>
>> +       list_for_each_entry(driver,&acpi_pci_drivers, node)
>> +               if (driver->add)
>> +                       driver->add(device->handle);
>> +
>>         return 0;
>
> if those calling is with acpi_pci_root_start() instead of acpi_pci_root_add()
>
> Do you still need patches 3?
I think it's still needed. If driver->add is called by
acpi_pci_root_add(), then acpi_pci_root_add() needs to
acquire the lock too.

>
> Yinghai
>
> .
>