* [PATCH v4 1/3] acpi : cpu hot-remove returns error when cpu_down() fails
@ 2012-07-13 8:48 ` Yasuaki Ishimatsu
0 siblings, 0 replies; 9+ messages in thread
From: Yasuaki Ishimatsu @ 2012-07-13 8:48 UTC (permalink / raw)
To: srivatsa.bhat, toshi.kani, lenb, linux-acpi, linux-kernel
Even if cpu_down() fails, acpi_processor_remove() continues to remove the cpu.
But in this case, it should return error number since some process may run on
the cpu. If the cpu has a running process and the cpu is turned the power off,
the system may not work well.
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
drivers/acpi/processor_driver.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
Index: linux-3.5-rc6/drivers/acpi/processor_driver.c
===================================================================
--- linux-3.5-rc6.orig/drivers/acpi/processor_driver.c 2012-07-08 09:23:56.000000000 +0900
+++ linux-3.5-rc6/drivers/acpi/processor_driver.c 2012-07-13 15:11:06.135541317 +0900
@@ -610,7 +610,7 @@ err_free_pr:
static int acpi_processor_remove(struct acpi_device *device, int type)
{
struct acpi_processor *pr = NULL;
-
+ int ret;
if (!device || !acpi_driver_data(device))
return -EINVAL;
@@ -621,8 +621,9 @@ static int acpi_processor_remove(struct
goto free;
if (type == ACPI_BUS_REMOVAL_EJECT) {
- if (acpi_processor_handle_eject(pr))
- return -EINVAL;
+ ret = acpi_processor_handle_eject(pr);
+ if (ret)
+ return ret;
}
acpi_processor_power_exit(pr, device);
@@ -841,12 +842,17 @@ static acpi_status acpi_processor_hotadd
static int acpi_processor_handle_eject(struct acpi_processor *pr)
{
- if (cpu_online(pr->id))
- cpu_down(pr->id);
+ int ret = 0;
+
+ if (cpu_online(pr->id)) {
+ ret = cpu_down(pr->id);
+ if (ret)
+ return ret;
+ }
arch_unregister_cpu(pr->id);
acpi_unmap_lsapic(pr->id);
- return (0);
+ return ret;
}
#else
static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
^ permalink raw reply [flat|nested] 9+ messages in thread* [PATCH v4 2/3] acpi : prevent cpu from becoming online
2012-07-13 8:48 ` Yasuaki Ishimatsu
@ 2012-07-13 8:51 ` Yasuaki Ishimatsu
-1 siblings, 0 replies; 9+ messages in thread
From: Yasuaki Ishimatsu @ 2012-07-13 8:51 UTC (permalink / raw)
To: srivatsa.bhat, toshi.kani, lenb, linux-acpi, linux-kernel
Even if acpi_processor_handle_eject() offlines cpu, there is a chance
to online the cpu after that. So the patch closes the window by using
get/put_online_cpus().
Why does the patch change _cpu_up() logic?
The patch cares the race of hot-remove cpu and _cpu_up(). If the patch
does not change it, there is the following race.
hot-remove cpu | _cpu_up()
------------------------------------- ------------------------------------
call acpi_processor_handle_eject() |
call cpu_down() |
call get_online_cpus() |
| call cpu_hotplug_begin() and stop here
call arch_unregister_cpu() |
call acpi_unmap_lsapic() |
call put_online_cpus() |
| start and continue _cpu_up()
return acpi_processor_remove() |
continue hot-remove the cpu |
So _cpu_up() can continue to itself. And hot-remove cpu can also continue
itself. If the patch changes _cpu_up() logic, the race disappears as below:
hot-remove cpu | _cpu_up()
-----------------------------------------------------------------------
call acpi_processor_handle_eject() |
call cpu_down() |
call get_online_cpus() |
| call cpu_hotplug_begin() and stop here
call arch_unregister_cpu() |
call acpi_unmap_lsapic() |
cpu's cpu_present is set |
to false by set_cpu_present()|
call put_online_cpus() |
| start _cpu_up()
| check cpu_present() and return -EINVAL
return acpi_processor_remove() |
continue hot-remove the cpu |
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
drivers/acpi/processor_driver.c | 14 ++++++++++++++
kernel/cpu.c | 8 +++++---
2 files changed, 19 insertions(+), 3 deletions(-)
Index: linux-3.5-rc6/drivers/acpi/processor_driver.c
===================================================================
--- linux-3.5-rc6.orig/drivers/acpi/processor_driver.c 2012-07-13 17:31:37.799130100 +0900
+++ linux-3.5-rc6/drivers/acpi/processor_driver.c 2012-07-13 17:39:47.727006338 +0900
@@ -850,8 +850,22 @@ static int acpi_processor_handle_eject(s
return ret;
}
+ get_online_cpus();
+ /*
+ * The cpu might become online again at this point. So we check whether
+ * the cpu has been onlined or not. If the cpu became online, it means
+ * that someone wants to use the cpu. So acpi_processor_handle_eject()
+ * returns -EAGAIN.
+ */
+ if (unlikely(cpu_online(pr->id))) {
+ put_online_cpus();
+ pr_warn("Failed to remove CPU %d, ", pr->id);
+ pr_warn("because other task brought the CPU back online\n");
+ return -EAGAIN;
+ }
arch_unregister_cpu(pr->id);
acpi_unmap_lsapic(pr->id);
+ put_online_cpus();
return ret;
}
#else
Index: linux-3.5-rc6/kernel/cpu.c
===================================================================
--- linux-3.5-rc6.orig/kernel/cpu.c 2012-07-13 17:31:37.800130087 +0900
+++ linux-3.5-rc6/kernel/cpu.c 2012-07-13 17:31:39.661106874 +0900
@@ -343,11 +343,13 @@ static int __cpuinit _cpu_up(unsigned in
unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
struct task_struct *idle;
- if (cpu_online(cpu) || !cpu_present(cpu))
- return -EINVAL;
-
cpu_hotplug_begin();
+ if (cpu_online(cpu) || !cpu_present(cpu)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
idle = idle_thread_get(cpu);
if (IS_ERR(idle)) {
ret = PTR_ERR(idle);
^ permalink raw reply [flat|nested] 9+ messages in thread* [PATCH v4 2/3] acpi : prevent cpu from becoming online
@ 2012-07-13 8:51 ` Yasuaki Ishimatsu
0 siblings, 0 replies; 9+ messages in thread
From: Yasuaki Ishimatsu @ 2012-07-13 8:51 UTC (permalink / raw)
To: srivatsa.bhat, toshi.kani, lenb, linux-acpi, linux-kernel
Even if acpi_processor_handle_eject() offlines cpu, there is a chance
to online the cpu after that. So the patch closes the window by using
get/put_online_cpus().
Why does the patch change _cpu_up() logic?
The patch cares the race of hot-remove cpu and _cpu_up(). If the patch
does not change it, there is the following race.
hot-remove cpu | _cpu_up()
------------------------------------- ------------------------------------
call acpi_processor_handle_eject() |
call cpu_down() |
call get_online_cpus() |
| call cpu_hotplug_begin() and stop here
call arch_unregister_cpu() |
call acpi_unmap_lsapic() |
call put_online_cpus() |
| start and continue _cpu_up()
return acpi_processor_remove() |
continue hot-remove the cpu |
So _cpu_up() can continue to itself. And hot-remove cpu can also continue
itself. If the patch changes _cpu_up() logic, the race disappears as below:
hot-remove cpu | _cpu_up()
-----------------------------------------------------------------------
call acpi_processor_handle_eject() |
call cpu_down() |
call get_online_cpus() |
| call cpu_hotplug_begin() and stop here
call arch_unregister_cpu() |
call acpi_unmap_lsapic() |
cpu's cpu_present is set |
to false by set_cpu_present()|
call put_online_cpus() |
| start _cpu_up()
| check cpu_present() and return -EINVAL
return acpi_processor_remove() |
continue hot-remove the cpu |
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
drivers/acpi/processor_driver.c | 14 ++++++++++++++
kernel/cpu.c | 8 +++++---
2 files changed, 19 insertions(+), 3 deletions(-)
Index: linux-3.5-rc6/drivers/acpi/processor_driver.c
===================================================================
--- linux-3.5-rc6.orig/drivers/acpi/processor_driver.c 2012-07-13 17:31:37.799130100 +0900
+++ linux-3.5-rc6/drivers/acpi/processor_driver.c 2012-07-13 17:39:47.727006338 +0900
@@ -850,8 +850,22 @@ static int acpi_processor_handle_eject(s
return ret;
}
+ get_online_cpus();
+ /*
+ * The cpu might become online again at this point. So we check whether
+ * the cpu has been onlined or not. If the cpu became online, it means
+ * that someone wants to use the cpu. So acpi_processor_handle_eject()
+ * returns -EAGAIN.
+ */
+ if (unlikely(cpu_online(pr->id))) {
+ put_online_cpus();
+ pr_warn("Failed to remove CPU %d, ", pr->id);
+ pr_warn("because other task brought the CPU back online\n");
+ return -EAGAIN;
+ }
arch_unregister_cpu(pr->id);
acpi_unmap_lsapic(pr->id);
+ put_online_cpus();
return ret;
}
#else
Index: linux-3.5-rc6/kernel/cpu.c
===================================================================
--- linux-3.5-rc6.orig/kernel/cpu.c 2012-07-13 17:31:37.800130087 +0900
+++ linux-3.5-rc6/kernel/cpu.c 2012-07-13 17:31:39.661106874 +0900
@@ -343,11 +343,13 @@ static int __cpuinit _cpu_up(unsigned in
unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
struct task_struct *idle;
- if (cpu_online(cpu) || !cpu_present(cpu))
- return -EINVAL;
-
cpu_hotplug_begin();
+ if (cpu_online(cpu) || !cpu_present(cpu)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
idle = idle_thread_get(cpu);
if (IS_ERR(idle)) {
ret = PTR_ERR(idle);
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH v4 2/3] acpi : prevent cpu from becoming online
2012-07-13 8:51 ` Yasuaki Ishimatsu
(?)
@ 2012-07-13 15:25 ` Toshi Kani
-1 siblings, 0 replies; 9+ messages in thread
From: Toshi Kani @ 2012-07-13 15:25 UTC (permalink / raw)
To: Yasuaki Ishimatsu; +Cc: srivatsa.bhat, lenb, linux-acpi, linux-kernel
On Fri, 2012-07-13 at 17:51 +0900, Yasuaki Ishimatsu wrote:
> Even if acpi_processor_handle_eject() offlines cpu, there is a chance
> to online the cpu after that. So the patch closes the window by using
> get/put_online_cpus().
>
> Why does the patch change _cpu_up() logic?
>
> The patch cares the race of hot-remove cpu and _cpu_up(). If the patch
> does not change it, there is the following race.
>
> hot-remove cpu | _cpu_up()
> ------------------------------------- ------------------------------------
> call acpi_processor_handle_eject() |
> call cpu_down() |
> call get_online_cpus() |
> | call cpu_hotplug_begin() and stop here
> call arch_unregister_cpu() |
> call acpi_unmap_lsapic() |
> call put_online_cpus() |
> | start and continue _cpu_up()
> return acpi_processor_remove() |
> continue hot-remove the cpu |
>
> So _cpu_up() can continue to itself. And hot-remove cpu can also continue
> itself. If the patch changes _cpu_up() logic, the race disappears as below:
>
> hot-remove cpu | _cpu_up()
> -----------------------------------------------------------------------
> call acpi_processor_handle_eject() |
> call cpu_down() |
> call get_online_cpus() |
> | call cpu_hotplug_begin() and stop here
> call arch_unregister_cpu() |
> call acpi_unmap_lsapic() |
> cpu's cpu_present is set |
> to false by set_cpu_present()|
> call put_online_cpus() |
> | start _cpu_up()
> | check cpu_present() and return -EINVAL
> return acpi_processor_remove() |
> continue hot-remove the cpu |
>
> Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>
> ---
> drivers/acpi/processor_driver.c | 14 ++++++++++++++
> kernel/cpu.c | 8 +++++---
> 2 files changed, 19 insertions(+), 3 deletions(-)
>
> Index: linux-3.5-rc6/drivers/acpi/processor_driver.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/acpi/processor_driver.c 2012-07-13 17:31:37.799130100 +0900
> +++ linux-3.5-rc6/drivers/acpi/processor_driver.c 2012-07-13 17:39:47.727006338 +0900
> @@ -850,8 +850,22 @@ static int acpi_processor_handle_eject(s
> return ret;
> }
>
> + get_online_cpus();
> + /*
> + * The cpu might become online again at this point. So we check whether
> + * the cpu has been onlined or not. If the cpu became online, it means
> + * that someone wants to use the cpu. So acpi_processor_handle_eject()
> + * returns -EAGAIN.
> + */
> + if (unlikely(cpu_online(pr->id))) {
> + put_online_cpus();
> + pr_warn("Failed to remove CPU %d, ", pr->id);
> + pr_warn("because other task brought the CPU back online\n");
Just a nit-pick, but you can simply do it like:
pr_warn("Failed to remove CPU %d, because other task "
"brought the CPU back online\n", pr->id);
Other than that,
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Thanks,
-Toshi
> + return -EAGAIN;
> + }
> arch_unregister_cpu(pr->id);
> acpi_unmap_lsapic(pr->id);
> + put_online_cpus();
> return ret;
> }
> #else
> Index: linux-3.5-rc6/kernel/cpu.c
> ===================================================================
> --- linux-3.5-rc6.orig/kernel/cpu.c 2012-07-13 17:31:37.800130087 +0900
> +++ linux-3.5-rc6/kernel/cpu.c 2012-07-13 17:31:39.661106874 +0900
> @@ -343,11 +343,13 @@ static int __cpuinit _cpu_up(unsigned in
> unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
> struct task_struct *idle;
>
> - if (cpu_online(cpu) || !cpu_present(cpu))
> - return -EINVAL;
> -
> cpu_hotplug_begin();
>
> + if (cpu_online(cpu) || !cpu_present(cpu)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> idle = idle_thread_get(cpu);
> if (IS_ERR(idle)) {
> ret = PTR_ERR(idle);
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v4 3/3] acpi : acpi_bus_trim() stops removing devices when failing to remove the device
2012-07-13 8:48 ` Yasuaki Ishimatsu
@ 2012-07-13 8:53 ` Yasuaki Ishimatsu
-1 siblings, 0 replies; 9+ messages in thread
From: Yasuaki Ishimatsu @ 2012-07-13 8:53 UTC (permalink / raw)
To: srivatsa.bhat, toshi.kani, lenb, linux-acpi, linux-kernel
acpi_bus_trim() stops removing devices, when acpi_bus_remove() return error
number. But acpi_bus_remove() cannot return error number correctly.
acpi_bus_remove() only return -EINVAL, when dev argument is NULL. Thus even if
device cannot be removed correctly, acpi_bus_trim() ignores and continues to
remove devices. acpi_bus_hot_remove_device() uses acpi_bus_trim() for removing
devices. Therefore acpi_bus_hot_remove_device() can send "_EJ0" to firmware,
even if the device is running on the system. In this case, the system cannot
work well. So acpi_bus_trim() should check whether device was removed or not
correctly. The patch adds error check into some functions to remove the device.
device_release_driver() can return error value by the patch. But the change
does not impact other caller function excluding acpi_bus_trim(), since all
of them does not check return value of device_releae_driver().
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
drivers/acpi/scan.c | 15 ++++++++++++---
drivers/base/dd.c | 22 +++++++++++++++++-----
include/linux/device.h | 2 +-
3 files changed, 30 insertions(+), 9 deletions(-)
Index: linux-3.5-rc6/drivers/acpi/scan.c
===================================================================
--- linux-3.5-rc6.orig/drivers/acpi/scan.c 2012-07-13 15:10:46.136790418 +0900
+++ linux-3.5-rc6/drivers/acpi/scan.c 2012-07-13 15:12:41.364349387 +0900
@@ -425,12 +425,17 @@ static int acpi_device_remove(struct dev
{
struct acpi_device *acpi_dev = to_acpi_device(dev);
struct acpi_driver *acpi_drv = acpi_dev->driver;
+ int ret;
if (acpi_drv) {
if (acpi_drv->ops.notify)
acpi_device_remove_notify_handler(acpi_dev);
- if (acpi_drv->ops.remove)
- acpi_drv->ops.remove(acpi_dev, acpi_dev->removal_type);
+ if (acpi_drv->ops.remove) {
+ ret = acpi_drv->ops.remove(acpi_dev,
+ acpi_dev->removal_type);
+ if (ret)
+ return ret;
+ }
}
acpi_dev->driver = NULL;
acpi_dev->driver_data = NULL;
@@ -1208,11 +1213,15 @@ static int acpi_device_set_context(struc
static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
{
+ int ret;
+
if (!dev)
return -EINVAL;
dev->removal_type = ACPI_BUS_REMOVAL_EJECT;
- device_release_driver(&dev->dev);
+ ret = device_release_driver(&dev->dev);
+ if (ret)
+ return ret;
if (!rmdevice)
return 0;
Index: linux-3.5-rc6/drivers/base/dd.c
===================================================================
--- linux-3.5-rc6.orig/drivers/base/dd.c 2012-07-13 15:10:46.136790418 +0900
+++ linux-3.5-rc6/drivers/base/dd.c 2012-07-13 15:14:13.895193383 +0900
@@ -464,9 +464,10 @@ EXPORT_SYMBOL_GPL(driver_attach);
* __device_release_driver() must be called with @dev lock held.
* When called for a USB interface, @dev->parent lock must be held as well.
*/
-static void __device_release_driver(struct device *dev)
+static int __device_release_driver(struct device *dev)
{
struct device_driver *drv;
+ int ret = 0;
drv = dev->driver;
if (drv) {
@@ -482,9 +483,11 @@ static void __device_release_driver(stru
pm_runtime_put_sync(dev);
if (dev->bus && dev->bus->remove)
- dev->bus->remove(dev);
+ ret = dev->bus->remove(dev);
else if (drv->remove)
- drv->remove(dev);
+ ret = drv->remove(dev);
+ if (ret)
+ goto rollback;
devres_release_all(dev);
dev->driver = NULL;
klist_remove(&dev->p->knode_driver);
@@ -494,6 +497,12 @@ static void __device_release_driver(stru
dev);
}
+
+ return ret;
+
+rollback:
+ driver_sysfs_add(dev);
+ return ret;
}
/**
@@ -503,16 +512,19 @@ static void __device_release_driver(stru
* Manually detach device from driver.
* When called for a USB interface, @dev->parent lock must be held.
*/
-void device_release_driver(struct device *dev)
+int device_release_driver(struct device *dev)
{
+ int ret;
/*
* If anyone calls device_release_driver() recursively from
* within their ->remove callback for the same device, they
* will deadlock right here.
*/
device_lock(dev);
- __device_release_driver(dev);
+ ret = __device_release_driver(dev);
device_unlock(dev);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(device_release_driver);
Index: linux-3.5-rc6/include/linux/device.h
===================================================================
--- linux-3.5-rc6.orig/include/linux/device.h 2012-07-13 15:10:46.137790406 +0900
+++ linux-3.5-rc6/include/linux/device.h 2012-07-13 15:12:41.371349562 +0900
@@ -827,7 +827,7 @@ static inline void *dev_get_platdata(con
* for information on use.
*/
extern int __must_check device_bind_driver(struct device *dev);
-extern void device_release_driver(struct device *dev);
+extern int device_release_driver(struct device *dev);
extern int __must_check device_attach(struct device *dev);
extern int __must_check driver_attach(struct device_driver *drv);
extern int __must_check device_reprobe(struct device *dev);
^ permalink raw reply [flat|nested] 9+ messages in thread* [PATCH v4 3/3] acpi : acpi_bus_trim() stops removing devices when failing to remove the device
@ 2012-07-13 8:53 ` Yasuaki Ishimatsu
0 siblings, 0 replies; 9+ messages in thread
From: Yasuaki Ishimatsu @ 2012-07-13 8:53 UTC (permalink / raw)
To: srivatsa.bhat, toshi.kani, lenb, linux-acpi, linux-kernel
acpi_bus_trim() stops removing devices, when acpi_bus_remove() return error
number. But acpi_bus_remove() cannot return error number correctly.
acpi_bus_remove() only return -EINVAL, when dev argument is NULL. Thus even if
device cannot be removed correctly, acpi_bus_trim() ignores and continues to
remove devices. acpi_bus_hot_remove_device() uses acpi_bus_trim() for removing
devices. Therefore acpi_bus_hot_remove_device() can send "_EJ0" to firmware,
even if the device is running on the system. In this case, the system cannot
work well. So acpi_bus_trim() should check whether device was removed or not
correctly. The patch adds error check into some functions to remove the device.
device_release_driver() can return error value by the patch. But the change
does not impact other caller function excluding acpi_bus_trim(), since all
of them does not check return value of device_releae_driver().
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
drivers/acpi/scan.c | 15 ++++++++++++---
drivers/base/dd.c | 22 +++++++++++++++++-----
include/linux/device.h | 2 +-
3 files changed, 30 insertions(+), 9 deletions(-)
Index: linux-3.5-rc6/drivers/acpi/scan.c
===================================================================
--- linux-3.5-rc6.orig/drivers/acpi/scan.c 2012-07-13 15:10:46.136790418 +0900
+++ linux-3.5-rc6/drivers/acpi/scan.c 2012-07-13 15:12:41.364349387 +0900
@@ -425,12 +425,17 @@ static int acpi_device_remove(struct dev
{
struct acpi_device *acpi_dev = to_acpi_device(dev);
struct acpi_driver *acpi_drv = acpi_dev->driver;
+ int ret;
if (acpi_drv) {
if (acpi_drv->ops.notify)
acpi_device_remove_notify_handler(acpi_dev);
- if (acpi_drv->ops.remove)
- acpi_drv->ops.remove(acpi_dev, acpi_dev->removal_type);
+ if (acpi_drv->ops.remove) {
+ ret = acpi_drv->ops.remove(acpi_dev,
+ acpi_dev->removal_type);
+ if (ret)
+ return ret;
+ }
}
acpi_dev->driver = NULL;
acpi_dev->driver_data = NULL;
@@ -1208,11 +1213,15 @@ static int acpi_device_set_context(struc
static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
{
+ int ret;
+
if (!dev)
return -EINVAL;
dev->removal_type = ACPI_BUS_REMOVAL_EJECT;
- device_release_driver(&dev->dev);
+ ret = device_release_driver(&dev->dev);
+ if (ret)
+ return ret;
if (!rmdevice)
return 0;
Index: linux-3.5-rc6/drivers/base/dd.c
===================================================================
--- linux-3.5-rc6.orig/drivers/base/dd.c 2012-07-13 15:10:46.136790418 +0900
+++ linux-3.5-rc6/drivers/base/dd.c 2012-07-13 15:14:13.895193383 +0900
@@ -464,9 +464,10 @@ EXPORT_SYMBOL_GPL(driver_attach);
* __device_release_driver() must be called with @dev lock held.
* When called for a USB interface, @dev->parent lock must be held as well.
*/
-static void __device_release_driver(struct device *dev)
+static int __device_release_driver(struct device *dev)
{
struct device_driver *drv;
+ int ret = 0;
drv = dev->driver;
if (drv) {
@@ -482,9 +483,11 @@ static void __device_release_driver(stru
pm_runtime_put_sync(dev);
if (dev->bus && dev->bus->remove)
- dev->bus->remove(dev);
+ ret = dev->bus->remove(dev);
else if (drv->remove)
- drv->remove(dev);
+ ret = drv->remove(dev);
+ if (ret)
+ goto rollback;
devres_release_all(dev);
dev->driver = NULL;
klist_remove(&dev->p->knode_driver);
@@ -494,6 +497,12 @@ static void __device_release_driver(stru
dev);
}
+
+ return ret;
+
+rollback:
+ driver_sysfs_add(dev);
+ return ret;
}
/**
@@ -503,16 +512,19 @@ static void __device_release_driver(stru
* Manually detach device from driver.
* When called for a USB interface, @dev->parent lock must be held.
*/
-void device_release_driver(struct device *dev)
+int device_release_driver(struct device *dev)
{
+ int ret;
/*
* If anyone calls device_release_driver() recursively from
* within their ->remove callback for the same device, they
* will deadlock right here.
*/
device_lock(dev);
- __device_release_driver(dev);
+ ret = __device_release_driver(dev);
device_unlock(dev);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(device_release_driver);
Index: linux-3.5-rc6/include/linux/device.h
===================================================================
--- linux-3.5-rc6.orig/include/linux/device.h 2012-07-13 15:10:46.137790406 +0900
+++ linux-3.5-rc6/include/linux/device.h 2012-07-13 15:12:41.371349562 +0900
@@ -827,7 +827,7 @@ static inline void *dev_get_platdata(con
* for information on use.
*/
extern int __must_check device_bind_driver(struct device *dev);
-extern void device_release_driver(struct device *dev);
+extern int device_release_driver(struct device *dev);
extern int __must_check device_attach(struct device *dev);
extern int __must_check driver_attach(struct device_driver *drv);
extern int __must_check device_reprobe(struct device *dev);
^ permalink raw reply [flat|nested] 9+ messages in thread* Re: [PATCH v4 3/3] acpi : acpi_bus_trim() stops removing devices when failing to remove the device
2012-07-13 8:53 ` Yasuaki Ishimatsu
(?)
@ 2012-07-13 15:54 ` Toshi Kani
-1 siblings, 0 replies; 9+ messages in thread
From: Toshi Kani @ 2012-07-13 15:54 UTC (permalink / raw)
To: Yasuaki Ishimatsu; +Cc: srivatsa.bhat, lenb, linux-acpi, linux-kernel
On Fri, 2012-07-13 at 17:53 +0900, Yasuaki Ishimatsu wrote:
> acpi_bus_trim() stops removing devices, when acpi_bus_remove() return error
> number. But acpi_bus_remove() cannot return error number correctly.
> acpi_bus_remove() only return -EINVAL, when dev argument is NULL. Thus even if
> device cannot be removed correctly, acpi_bus_trim() ignores and continues to
> remove devices. acpi_bus_hot_remove_device() uses acpi_bus_trim() for removing
> devices. Therefore acpi_bus_hot_remove_device() can send "_EJ0" to firmware,
> even if the device is running on the system. In this case, the system cannot
> work well. So acpi_bus_trim() should check whether device was removed or not
> correctly. The patch adds error check into some functions to remove the device.
>
> device_release_driver() can return error value by the patch. But the change
> does not impact other caller function excluding acpi_bus_trim(), since all
> of them does not check return value of device_releae_driver().
I think potential risk here is that __device_release_driver() now
performs rollback in case of error from driver's remove interface. I
agree with doing the rollback, but this leads to a different situation
if the caller does not check error from device_release_driver() and
proceeds the operation. So, we will need to make sure that:
- Other driver's remove interfaces do not fail (or very unlikely to
fail), or
- If other driver's remove interfaces failed, their end results are no
worse than today.
Thanks,
-Toshi
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>
> ---
> drivers/acpi/scan.c | 15 ++++++++++++---
> drivers/base/dd.c | 22 +++++++++++++++++-----
> include/linux/device.h | 2 +-
> 3 files changed, 30 insertions(+), 9 deletions(-)
>
> Index: linux-3.5-rc6/drivers/acpi/scan.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/acpi/scan.c 2012-07-13 15:10:46.136790418 +0900
> +++ linux-3.5-rc6/drivers/acpi/scan.c 2012-07-13 15:12:41.364349387 +0900
> @@ -425,12 +425,17 @@ static int acpi_device_remove(struct dev
> {
> struct acpi_device *acpi_dev = to_acpi_device(dev);
> struct acpi_driver *acpi_drv = acpi_dev->driver;
> + int ret;
>
> if (acpi_drv) {
> if (acpi_drv->ops.notify)
> acpi_device_remove_notify_handler(acpi_dev);
> - if (acpi_drv->ops.remove)
> - acpi_drv->ops.remove(acpi_dev, acpi_dev->removal_type);
> + if (acpi_drv->ops.remove) {
> + ret = acpi_drv->ops.remove(acpi_dev,
> + acpi_dev->removal_type);
> + if (ret)
> + return ret;
> + }
> }
> acpi_dev->driver = NULL;
> acpi_dev->driver_data = NULL;
> @@ -1208,11 +1213,15 @@ static int acpi_device_set_context(struc
>
> static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
> {
> + int ret;
> +
> if (!dev)
> return -EINVAL;
>
> dev->removal_type = ACPI_BUS_REMOVAL_EJECT;
> - device_release_driver(&dev->dev);
> + ret = device_release_driver(&dev->dev);
> + if (ret)
> + return ret;
>
> if (!rmdevice)
> return 0;
> Index: linux-3.5-rc6/drivers/base/dd.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/base/dd.c 2012-07-13 15:10:46.136790418 +0900
> +++ linux-3.5-rc6/drivers/base/dd.c 2012-07-13 15:14:13.895193383 +0900
> @@ -464,9 +464,10 @@ EXPORT_SYMBOL_GPL(driver_attach);
> * __device_release_driver() must be called with @dev lock held.
> * When called for a USB interface, @dev->parent lock must be held as well.
> */
> -static void __device_release_driver(struct device *dev)
> +static int __device_release_driver(struct device *dev)
> {
> struct device_driver *drv;
> + int ret = 0;
>
> drv = dev->driver;
> if (drv) {
> @@ -482,9 +483,11 @@ static void __device_release_driver(stru
> pm_runtime_put_sync(dev);
>
> if (dev->bus && dev->bus->remove)
> - dev->bus->remove(dev);
> + ret = dev->bus->remove(dev);
> else if (drv->remove)
> - drv->remove(dev);
> + ret = drv->remove(dev);
> + if (ret)
> + goto rollback;
> devres_release_all(dev);
> dev->driver = NULL;
> klist_remove(&dev->p->knode_driver);
> @@ -494,6 +497,12 @@ static void __device_release_driver(stru
> dev);
>
> }
> +
> + return ret;
> +
> +rollback:
> + driver_sysfs_add(dev);
> + return ret;
> }
>
> /**
> @@ -503,16 +512,19 @@ static void __device_release_driver(stru
> * Manually detach device from driver.
> * When called for a USB interface, @dev->parent lock must be held.
> */
> -void device_release_driver(struct device *dev)
> +int device_release_driver(struct device *dev)
> {
> + int ret;
> /*
> * If anyone calls device_release_driver() recursively from
> * within their ->remove callback for the same device, they
> * will deadlock right here.
> */
> device_lock(dev);
> - __device_release_driver(dev);
> + ret = __device_release_driver(dev);
> device_unlock(dev);
> +
> + return ret;
> }
> EXPORT_SYMBOL_GPL(device_release_driver);
>
> Index: linux-3.5-rc6/include/linux/device.h
> ===================================================================
> --- linux-3.5-rc6.orig/include/linux/device.h 2012-07-13 15:10:46.137790406 +0900
> +++ linux-3.5-rc6/include/linux/device.h 2012-07-13 15:12:41.371349562 +0900
> @@ -827,7 +827,7 @@ static inline void *dev_get_platdata(con
> * for information on use.
> */
> extern int __must_check device_bind_driver(struct device *dev);
> -extern void device_release_driver(struct device *dev);
> +extern int device_release_driver(struct device *dev);
> extern int __must_check device_attach(struct device *dev);
> extern int __must_check driver_attach(struct device_driver *drv);
> extern int __must_check device_reprobe(struct device *dev);
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4 1/3] acpi : cpu hot-remove returns error when cpu_down() fails
2012-07-13 8:48 ` Yasuaki Ishimatsu
` (2 preceding siblings ...)
(?)
@ 2012-07-13 15:20 ` Toshi Kani
-1 siblings, 0 replies; 9+ messages in thread
From: Toshi Kani @ 2012-07-13 15:20 UTC (permalink / raw)
To: Yasuaki Ishimatsu; +Cc: srivatsa.bhat, lenb, linux-acpi, linux-kernel
On Fri, 2012-07-13 at 17:48 +0900, Yasuaki Ishimatsu wrote:
> Even if cpu_down() fails, acpi_processor_remove() continues to remove the cpu.
> But in this case, it should return error number since some process may run on
> the cpu. If the cpu has a running process and the cpu is turned the power off,
> the system may not work well.
>
> Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Thanks for the update. It looks good.
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
>
> ---
> drivers/acpi/processor_driver.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> Index: linux-3.5-rc6/drivers/acpi/processor_driver.c
> ===================================================================
> --- linux-3.5-rc6.orig/drivers/acpi/processor_driver.c 2012-07-08 09:23:56.000000000 +0900
> +++ linux-3.5-rc6/drivers/acpi/processor_driver.c 2012-07-13 15:11:06.135541317 +0900
> @@ -610,7 +610,7 @@ err_free_pr:
> static int acpi_processor_remove(struct acpi_device *device, int type)
> {
> struct acpi_processor *pr = NULL;
> -
> + int ret;
>
> if (!device || !acpi_driver_data(device))
> return -EINVAL;
> @@ -621,8 +621,9 @@ static int acpi_processor_remove(struct
> goto free;
>
> if (type == ACPI_BUS_REMOVAL_EJECT) {
> - if (acpi_processor_handle_eject(pr))
> - return -EINVAL;
> + ret = acpi_processor_handle_eject(pr);
> + if (ret)
> + return ret;
> }
>
> acpi_processor_power_exit(pr, device);
> @@ -841,12 +842,17 @@ static acpi_status acpi_processor_hotadd
>
> static int acpi_processor_handle_eject(struct acpi_processor *pr)
> {
> - if (cpu_online(pr->id))
> - cpu_down(pr->id);
> + int ret = 0;
> +
> + if (cpu_online(pr->id)) {
> + ret = cpu_down(pr->id);
> + if (ret)
> + return ret;
> + }
>
> arch_unregister_cpu(pr->id);
> acpi_unmap_lsapic(pr->id);
> - return (0);
> + return ret;
> }
> #else
> static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
>
^ permalink raw reply [flat|nested] 9+ messages in thread