Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
Thank you. That fixed the alpha allmodconfig case for me. I am currently
rebuilding all the arm defconfig files and will resubmit -v10 when that
is done.
Robin
On Sat, May 11, 2013 at 02:43:20PM +0530, Srivatsa S. Bhat wrote:
> On 05/11/2013 09:46 AM, Robin Holt wrote:
> > On Fri, May 10, 2013 at 10:03:24AM -0700, Andrew Morton wrote:
> >> On Fri, 10 May 2013 13:11:51 +0200 "Rafael J. Wysocki"
> >> wrote:
> >>
> >>> ...
> >>>
> cpu_hotplug_disable() doesn't get compiled unless we've defined
> CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
> behind that!
> >>>
> >>> I suppose it was only used by suspend/hibernate code paths when this was
> >>> introduced.
> >>
> >> OK, well I suspect that what I have now is simply wrong for Robin's
> >> application. Robin, can you please check this? We probably want to
> >> make the does-something version of cpu_hotplug_disable/enable available
> >> if CONFIG_HOTPLUG_CPU.
> >
> > This patch came from "Srivatsa S. Bhat" ,
> > I think I need to defer.
>
> Here is a revised patch, which should address all the problems, IMHO.
> Let me know if you face any issues. (And thanks a lot for fixing up the
> !SMP case in the previous version.)
>
> ->
>
> From: Srivatsa S. Bhat
> Subject: [PATCH] CPU hotplug: Provide a generic helper to disable/enable CPU
> hotplug
>
> There are instances in the kernel where we would like to disable
> CPU hotplug (from sysfs) during some important operation. Today
> the freezer code depends on this and the code to do it was kinda
> tailor-made for that.
>
> Restructure the code and make it generic enough to be useful for
> other usecases too.
>
> Signed-off-by: Srivatsa S. Bhat
> ---
>
> include/linux/cpu.h |4
> kernel/cpu.c| 55
> +--
> 2 files changed, 27 insertions(+), 32 deletions(-)
>
> diff --git a/include/linux/cpu.h b/include/linux/cpu.h
> index c6f6e08..9f3c7e8 100644
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -175,6 +175,8 @@ extern struct bus_type cpu_subsys;
>
> extern void get_online_cpus(void);
> extern void put_online_cpus(void);
> +extern void cpu_hotplug_disable(void);
> +extern void cpu_hotplug_enable(void);
> #define hotcpu_notifier(fn, pri) cpu_notifier(fn, pri)
> #define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
> #define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
> @@ -198,6 +200,8 @@ static inline void cpu_hotplug_driver_unlock(void)
>
> #define get_online_cpus()do { } while (0)
> #define put_online_cpus()do { } while (0)
> +#define cpu_hotplug_disable()do { } while (0)
> +#define cpu_hotplug_enable() do { } while (0)
> #define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
> /* These aren't inline functions due to a GCC bug. */
> #define register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index b5e4ab2..198a388 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -133,6 +133,27 @@ static void cpu_hotplug_done(void)
> mutex_unlock(_hotplug.lock);
> }
>
> +/*
> + * Wait for currently running CPU hotplug operations to complete (if any) and
> + * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock'
> protects
> + * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
> + * hotplug path before performing hotplug operations. So acquiring that lock
> + * guarantees mutual exclusion from any currently running hotplug operations.
> + */
> +void cpu_hotplug_disable(void)
> +{
> + cpu_maps_update_begin();
> + cpu_hotplug_disabled = 1;
> + cpu_maps_update_done();
> +}
> +
> +void cpu_hotplug_enable(void)
> +{
> + cpu_maps_update_begin();
> + cpu_hotplug_disabled = 0;
> + cpu_maps_update_done();
> +}
> +
> #else /* #if CONFIG_HOTPLUG_CPU */
> static void cpu_hotplug_begin(void) {}
> static void cpu_hotplug_done(void) {}
> @@ -541,36 +562,6 @@ static int __init alloc_frozen_cpus(void)
> core_initcall(alloc_frozen_cpus);
>
> /*
> - * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
> - * hotplug when tasks are about to be frozen. Also, don't allow the freezer
> - * to continue until any currently running CPU hotplug operation gets
> - * completed.
> - * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
> - * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
> - * CPU hotplug path and released only after it is complete. Thus, we
> - * (and hence the freezer) will block here until any currently running CPU
> - * hotplug operation gets completed.
> - */
> -void cpu_hotplug_disable_before_freeze(void)
> -{
> - cpu_maps_update_begin();
> - cpu_hotplug_disabled = 1;
> - cpu_maps_update_done();
> -}
> -
> -
> -/*
> - * When tasks have been thawed, re-enable regular CPU hotplug
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On 05/11/2013 09:46 AM, Robin Holt wrote:
> On Fri, May 10, 2013 at 10:03:24AM -0700, Andrew Morton wrote:
>> On Fri, 10 May 2013 13:11:51 +0200 "Rafael J. Wysocki" wrote:
>>
>>> ...
>>>
cpu_hotplug_disable() doesn't get compiled unless we've defined
CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
behind that!
>>>
>>> I suppose it was only used by suspend/hibernate code paths when this was
>>> introduced.
>>
>> OK, well I suspect that what I have now is simply wrong for Robin's
>> application. Robin, can you please check this? We probably want to
>> make the does-something version of cpu_hotplug_disable/enable available
>> if CONFIG_HOTPLUG_CPU.
>
> This patch came from "Srivatsa S. Bhat" ,
> I think I need to defer.
Here is a revised patch, which should address all the problems, IMHO.
Let me know if you face any issues. (And thanks a lot for fixing up the
!SMP case in the previous version.)
->
From: Srivatsa S. Bhat
Subject: [PATCH] CPU hotplug: Provide a generic helper to disable/enable CPU
hotplug
There are instances in the kernel where we would like to disable
CPU hotplug (from sysfs) during some important operation. Today
the freezer code depends on this and the code to do it was kinda
tailor-made for that.
Restructure the code and make it generic enough to be useful for
other usecases too.
Signed-off-by: Srivatsa S. Bhat
---
include/linux/cpu.h |4
kernel/cpu.c| 55 +--
2 files changed, 27 insertions(+), 32 deletions(-)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index c6f6e08..9f3c7e8 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -175,6 +175,8 @@ extern struct bus_type cpu_subsys;
extern void get_online_cpus(void);
extern void put_online_cpus(void);
+extern void cpu_hotplug_disable(void);
+extern void cpu_hotplug_enable(void);
#define hotcpu_notifier(fn, pri) cpu_notifier(fn, pri)
#define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
#define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
@@ -198,6 +200,8 @@ static inline void cpu_hotplug_driver_unlock(void)
#define get_online_cpus() do { } while (0)
#define put_online_cpus() do { } while (0)
+#define cpu_hotplug_disable() do { } while (0)
+#define cpu_hotplug_enable() do { } while (0)
#define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
/* These aren't inline functions due to a GCC bug. */
#define register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
diff --git a/kernel/cpu.c b/kernel/cpu.c
index b5e4ab2..198a388 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -133,6 +133,27 @@ static void cpu_hotplug_done(void)
mutex_unlock(_hotplug.lock);
}
+/*
+ * Wait for currently running CPU hotplug operations to complete (if any) and
+ * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
+ * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
+ * hotplug path before performing hotplug operations. So acquiring that lock
+ * guarantees mutual exclusion from any currently running hotplug operations.
+ */
+void cpu_hotplug_disable(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 1;
+ cpu_maps_update_done();
+}
+
+void cpu_hotplug_enable(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 0;
+ cpu_maps_update_done();
+}
+
#else /* #if CONFIG_HOTPLUG_CPU */
static void cpu_hotplug_begin(void) {}
static void cpu_hotplug_done(void) {}
@@ -541,36 +562,6 @@ static int __init alloc_frozen_cpus(void)
core_initcall(alloc_frozen_cpus);
/*
- * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
- * hotplug when tasks are about to be frozen. Also, don't allow the freezer
- * to continue until any currently running CPU hotplug operation gets
- * completed.
- * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
- * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
- * CPU hotplug path and released only after it is complete. Thus, we
- * (and hence the freezer) will block here until any currently running CPU
- * hotplug operation gets completed.
- */
-void cpu_hotplug_disable_before_freeze(void)
-{
- cpu_maps_update_begin();
- cpu_hotplug_disabled = 1;
- cpu_maps_update_done();
-}
-
-
-/*
- * When tasks have been thawed, re-enable regular CPU hotplug (which had been
- * disabled while beginning to freeze tasks).
- */
-void cpu_hotplug_enable_after_thaw(void)
-{
- cpu_maps_update_begin();
- cpu_hotplug_disabled = 0;
- cpu_maps_update_done();
-}
-
-/*
* When callbacks for CPU hotplug notifications are being executed, we must
* ensure that the state of the system with respect to the tasks being frozen
* or not, as reported by the notification, remains unchanged *throughout the
@@ -589,12
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On 05/11/2013 09:46 AM, Robin Holt wrote:
On Fri, May 10, 2013 at 10:03:24AM -0700, Andrew Morton wrote:
On Fri, 10 May 2013 13:11:51 +0200 Rafael J. Wysocki r...@sisk.pl wrote:
...
cpu_hotplug_disable() doesn't get compiled unless we've defined
CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
behind that!
I suppose it was only used by suspend/hibernate code paths when this was
introduced.
OK, well I suspect that what I have now is simply wrong for Robin's
application. Robin, can you please check this? We probably want to
make the does-something version of cpu_hotplug_disable/enable available
if CONFIG_HOTPLUG_CPU.
This patch came from Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com,
I think I need to defer.
Here is a revised patch, which should address all the problems, IMHO.
Let me know if you face any issues. (And thanks a lot for fixing up the
!SMP case in the previous version.)
-
From: Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com
Subject: [PATCH] CPU hotplug: Provide a generic helper to disable/enable CPU
hotplug
There are instances in the kernel where we would like to disable
CPU hotplug (from sysfs) during some important operation. Today
the freezer code depends on this and the code to do it was kinda
tailor-made for that.
Restructure the code and make it generic enough to be useful for
other usecases too.
Signed-off-by: Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com
---
include/linux/cpu.h |4
kernel/cpu.c| 55 +--
2 files changed, 27 insertions(+), 32 deletions(-)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index c6f6e08..9f3c7e8 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -175,6 +175,8 @@ extern struct bus_type cpu_subsys;
extern void get_online_cpus(void);
extern void put_online_cpus(void);
+extern void cpu_hotplug_disable(void);
+extern void cpu_hotplug_enable(void);
#define hotcpu_notifier(fn, pri) cpu_notifier(fn, pri)
#define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
#define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
@@ -198,6 +200,8 @@ static inline void cpu_hotplug_driver_unlock(void)
#define get_online_cpus() do { } while (0)
#define put_online_cpus() do { } while (0)
+#define cpu_hotplug_disable() do { } while (0)
+#define cpu_hotplug_enable() do { } while (0)
#define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
/* These aren't inline functions due to a GCC bug. */
#define register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
diff --git a/kernel/cpu.c b/kernel/cpu.c
index b5e4ab2..198a388 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -133,6 +133,27 @@ static void cpu_hotplug_done(void)
mutex_unlock(cpu_hotplug.lock);
}
+/*
+ * Wait for currently running CPU hotplug operations to complete (if any) and
+ * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
+ * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
+ * hotplug path before performing hotplug operations. So acquiring that lock
+ * guarantees mutual exclusion from any currently running hotplug operations.
+ */
+void cpu_hotplug_disable(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 1;
+ cpu_maps_update_done();
+}
+
+void cpu_hotplug_enable(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 0;
+ cpu_maps_update_done();
+}
+
#else /* #if CONFIG_HOTPLUG_CPU */
static void cpu_hotplug_begin(void) {}
static void cpu_hotplug_done(void) {}
@@ -541,36 +562,6 @@ static int __init alloc_frozen_cpus(void)
core_initcall(alloc_frozen_cpus);
/*
- * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
- * hotplug when tasks are about to be frozen. Also, don't allow the freezer
- * to continue until any currently running CPU hotplug operation gets
- * completed.
- * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
- * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
- * CPU hotplug path and released only after it is complete. Thus, we
- * (and hence the freezer) will block here until any currently running CPU
- * hotplug operation gets completed.
- */
-void cpu_hotplug_disable_before_freeze(void)
-{
- cpu_maps_update_begin();
- cpu_hotplug_disabled = 1;
- cpu_maps_update_done();
-}
-
-
-/*
- * When tasks have been thawed, re-enable regular CPU hotplug (which had been
- * disabled while beginning to freeze tasks).
- */
-void cpu_hotplug_enable_after_thaw(void)
-{
- cpu_maps_update_begin();
- cpu_hotplug_disabled = 0;
- cpu_maps_update_done();
-}
-
-/*
* When callbacks for CPU hotplug notifications are being executed, we must
* ensure that the state of the system with respect to the tasks being frozen
* or not, as reported by the
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
Thank you. That fixed the alpha allmodconfig case for me. I am currently
rebuilding all the arm defconfig files and will resubmit -v10 when that
is done.
Robin
On Sat, May 11, 2013 at 02:43:20PM +0530, Srivatsa S. Bhat wrote:
On 05/11/2013 09:46 AM, Robin Holt wrote:
On Fri, May 10, 2013 at 10:03:24AM -0700, Andrew Morton wrote:
On Fri, 10 May 2013 13:11:51 +0200 Rafael J. Wysocki r...@sisk.pl
wrote:
...
cpu_hotplug_disable() doesn't get compiled unless we've defined
CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
behind that!
I suppose it was only used by suspend/hibernate code paths when this was
introduced.
OK, well I suspect that what I have now is simply wrong for Robin's
application. Robin, can you please check this? We probably want to
make the does-something version of cpu_hotplug_disable/enable available
if CONFIG_HOTPLUG_CPU.
This patch came from Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com,
I think I need to defer.
Here is a revised patch, which should address all the problems, IMHO.
Let me know if you face any issues. (And thanks a lot for fixing up the
!SMP case in the previous version.)
-
From: Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com
Subject: [PATCH] CPU hotplug: Provide a generic helper to disable/enable CPU
hotplug
There are instances in the kernel where we would like to disable
CPU hotplug (from sysfs) during some important operation. Today
the freezer code depends on this and the code to do it was kinda
tailor-made for that.
Restructure the code and make it generic enough to be useful for
other usecases too.
Signed-off-by: Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com
---
include/linux/cpu.h |4
kernel/cpu.c| 55
+--
2 files changed, 27 insertions(+), 32 deletions(-)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index c6f6e08..9f3c7e8 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -175,6 +175,8 @@ extern struct bus_type cpu_subsys;
extern void get_online_cpus(void);
extern void put_online_cpus(void);
+extern void cpu_hotplug_disable(void);
+extern void cpu_hotplug_enable(void);
#define hotcpu_notifier(fn, pri) cpu_notifier(fn, pri)
#define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
#define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
@@ -198,6 +200,8 @@ static inline void cpu_hotplug_driver_unlock(void)
#define get_online_cpus()do { } while (0)
#define put_online_cpus()do { } while (0)
+#define cpu_hotplug_disable()do { } while (0)
+#define cpu_hotplug_enable() do { } while (0)
#define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
/* These aren't inline functions due to a GCC bug. */
#define register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
diff --git a/kernel/cpu.c b/kernel/cpu.c
index b5e4ab2..198a388 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -133,6 +133,27 @@ static void cpu_hotplug_done(void)
mutex_unlock(cpu_hotplug.lock);
}
+/*
+ * Wait for currently running CPU hotplug operations to complete (if any) and
+ * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock'
protects
+ * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
+ * hotplug path before performing hotplug operations. So acquiring that lock
+ * guarantees mutual exclusion from any currently running hotplug operations.
+ */
+void cpu_hotplug_disable(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 1;
+ cpu_maps_update_done();
+}
+
+void cpu_hotplug_enable(void)
+{
+ cpu_maps_update_begin();
+ cpu_hotplug_disabled = 0;
+ cpu_maps_update_done();
+}
+
#else /* #if CONFIG_HOTPLUG_CPU */
static void cpu_hotplug_begin(void) {}
static void cpu_hotplug_done(void) {}
@@ -541,36 +562,6 @@ static int __init alloc_frozen_cpus(void)
core_initcall(alloc_frozen_cpus);
/*
- * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
- * hotplug when tasks are about to be frozen. Also, don't allow the freezer
- * to continue until any currently running CPU hotplug operation gets
- * completed.
- * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
- * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
- * CPU hotplug path and released only after it is complete. Thus, we
- * (and hence the freezer) will block here until any currently running CPU
- * hotplug operation gets completed.
- */
-void cpu_hotplug_disable_before_freeze(void)
-{
- cpu_maps_update_begin();
- cpu_hotplug_disabled = 1;
- cpu_maps_update_done();
-}
-
-
-/*
- * When tasks have been thawed, re-enable regular CPU hotplug (which had been
- * disabled while beginning to freeze tasks).
-
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Fri, May 10, 2013 at 10:03:24AM -0700, Andrew Morton wrote: > On Fri, 10 May 2013 13:11:51 +0200 "Rafael J. Wysocki" wrote: > > > ... > > > > > cpu_hotplug_disable() doesn't get compiled unless we've defined > > > CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is > > > behind that! > > > > I suppose it was only used by suspend/hibernate code paths when this was > > introduced. > > OK, well I suspect that what I have now is simply wrong for Robin's > application. Robin, can you please check this? We probably want to > make the does-something version of cpu_hotplug_disable/enable available > if CONFIG_HOTPLUG_CPU. This patch came from "Srivatsa S. Bhat" , I think I need to defer. I spent all day trying to get an alpha cross compiler to build an unmodified kernel and modules, only to find I didn't need to go that far and could reproduce the failure with just building vmlinux. Sorry for my slow response, Robin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Fri, 10 May 2013 13:11:51 +0200 "Rafael J. Wysocki" wrote: > ... > > > cpu_hotplug_disable() doesn't get compiled unless we've defined > > CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is > > behind that! > > I suppose it was only used by suspend/hibernate code paths when this was > introduced. OK, well I suspect that what I have now is simply wrong for Robin's application. Robin, can you please check this? We probably want to make the does-something version of cpu_hotplug_disable/enable available if CONFIG_HOTPLUG_CPU. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Thursday, May 09, 2013 03:01:21 PM Andrew Morton wrote:
> On Tue, 7 May 2013 09:39:45 -0500 Robin Holt wrote:
>
> > From: "Srivatsa S. Bhat"
> >
> > There are instances in the kernel where we would like to disable
> > CPU hotplug (from sysfs) during some important operation. Today
> > the freezer code depends on this and the code to do it was kinda
> > tailor-made for that.
> >
> > Restructure the code and make it generic enough to be useful for
> > other usecases too.
> >
> > ...
> >
> > --- a/include/linux/cpu.h
> > +++ b/include/linux/cpu.h
> > @@ -141,6 +141,8 @@ static inline void unregister_cpu_notifier(struct
> > notifier_block *nb)
> > }
> > #endif
> >
> > +extern void cpu_hotplug_disable(void);
> > +extern void cpu_hotplug_enable(void);
> > int cpu_up(unsigned int cpu);
> > void notify_cpu_starting(unsigned int cpu);
> > extern void cpu_maps_update_begin(void);
> > @@ -148,6 +150,7 @@ extern void cpu_maps_update_done(void);
> >
> > #else /* CONFIG_SMP */
> >
> > +#define cpu_hotplug_disable() do { } while (0)
> > #define cpu_notifier(fn, pri) do { (void)(fn); } while (0)
> >
>
> Breaks alpha allmodconfig because cpu_hotplug_disable() is absent from
> vmlinux.
>
> cpu_hotplug_disable() doesn't get compiled unless we've defined
> CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
> behind that!
I suppose it was only used by suspend/hibernate code paths when this was
introduced.
Thanks,
Rafael
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Thursday, May 09, 2013 03:01:21 PM Andrew Morton wrote:
On Tue, 7 May 2013 09:39:45 -0500 Robin Holt h...@sgi.com wrote:
From: Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com
There are instances in the kernel where we would like to disable
CPU hotplug (from sysfs) during some important operation. Today
the freezer code depends on this and the code to do it was kinda
tailor-made for that.
Restructure the code and make it generic enough to be useful for
other usecases too.
...
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -141,6 +141,8 @@ static inline void unregister_cpu_notifier(struct
notifier_block *nb)
}
#endif
+extern void cpu_hotplug_disable(void);
+extern void cpu_hotplug_enable(void);
int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
@@ -148,6 +150,7 @@ extern void cpu_maps_update_done(void);
#else /* CONFIG_SMP */
+#define cpu_hotplug_disable() do { } while (0)
#define cpu_notifier(fn, pri) do { (void)(fn); } while (0)
Breaks alpha allmodconfig because cpu_hotplug_disable() is absent from
vmlinux.
cpu_hotplug_disable() doesn't get compiled unless we've defined
CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
behind that!
I suppose it was only used by suspend/hibernate code paths when this was
introduced.
Thanks,
Rafael
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Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Fri, 10 May 2013 13:11:51 +0200 Rafael J. Wysocki r...@sisk.pl wrote: ... cpu_hotplug_disable() doesn't get compiled unless we've defined CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is behind that! I suppose it was only used by suspend/hibernate code paths when this was introduced. OK, well I suspect that what I have now is simply wrong for Robin's application. Robin, can you please check this? We probably want to make the does-something version of cpu_hotplug_disable/enable available if CONFIG_HOTPLUG_CPU. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Fri, May 10, 2013 at 10:03:24AM -0700, Andrew Morton wrote: On Fri, 10 May 2013 13:11:51 +0200 Rafael J. Wysocki r...@sisk.pl wrote: ... cpu_hotplug_disable() doesn't get compiled unless we've defined CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is behind that! I suppose it was only used by suspend/hibernate code paths when this was introduced. OK, well I suspect that what I have now is simply wrong for Robin's application. Robin, can you please check this? We probably want to make the does-something version of cpu_hotplug_disable/enable available if CONFIG_HOTPLUG_CPU. This patch came from Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com, I think I need to defer. I spent all day trying to get an alpha cross compiler to build an unmodified kernel and modules, only to find I didn't need to go that far and could reproduce the failure with just building vmlinux. Sorry for my slow response, Robin -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Tue, 7 May 2013 09:39:45 -0500 Robin Holt wrote:
> From: "Srivatsa S. Bhat"
>
> There are instances in the kernel where we would like to disable
> CPU hotplug (from sysfs) during some important operation. Today
> the freezer code depends on this and the code to do it was kinda
> tailor-made for that.
>
> Restructure the code and make it generic enough to be useful for
> other usecases too.
>
> ...
>
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -141,6 +141,8 @@ static inline void unregister_cpu_notifier(struct
> notifier_block *nb)
> }
> #endif
>
> +extern void cpu_hotplug_disable(void);
> +extern void cpu_hotplug_enable(void);
> int cpu_up(unsigned int cpu);
> void notify_cpu_starting(unsigned int cpu);
> extern void cpu_maps_update_begin(void);
> @@ -148,6 +150,7 @@ extern void cpu_maps_update_done(void);
>
> #else/* CONFIG_SMP */
>
> +#define cpu_hotplug_disable()do { } while (0)
> #define cpu_notifier(fn, pri)do { (void)(fn); } while (0)
>
Breaks alpha allmodconfig because cpu_hotplug_disable() is absent from
vmlinux.
cpu_hotplug_disable() doesn't get compiled unless we've defined
CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
behind that!
I'll stick this in there and see what happens.
---
a/include/linux/cpu.h~cpu-hotplug-provide-a-generic-helper-to-disable-enable-cpu-hotplug-fix
+++ a/include/linux/cpu.h
@@ -141,8 +141,6 @@ static inline void unregister_cpu_notifi
}
#endif
-extern void cpu_hotplug_disable(void);
-extern void cpu_hotplug_enable(void);
int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
@@ -150,7 +148,6 @@ extern void cpu_maps_update_done(void);
#else /* CONFIG_SMP */
-#define cpu_hotplug_disable() do { } while (0)
#define cpu_notifier(fn, pri) do { (void)(fn); } while (0)
static inline int register_cpu_notifier(struct notifier_block *nb)
@@ -171,6 +168,15 @@ static inline void cpu_maps_update_done(
}
#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_PM_SLEEP_SMP
+extern void cpu_hotplug_enable(void);
+extern void cpu_hotplug_disable(void);
+#else
+#define cpu_hotplug_enable() do { } while (0)
+#define cpu_hotplug_disable() do { } while (0)
+#endif
+
extern struct bus_type cpu_subsys;
#ifdef CONFIG_HOTPLUG_CPU
--
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Re: [PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
On Tue, 7 May 2013 09:39:45 -0500 Robin Holt h...@sgi.com wrote:
From: Srivatsa S. Bhat srivatsa.b...@linux.vnet.ibm.com
There are instances in the kernel where we would like to disable
CPU hotplug (from sysfs) during some important operation. Today
the freezer code depends on this and the code to do it was kinda
tailor-made for that.
Restructure the code and make it generic enough to be useful for
other usecases too.
...
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -141,6 +141,8 @@ static inline void unregister_cpu_notifier(struct
notifier_block *nb)
}
#endif
+extern void cpu_hotplug_disable(void);
+extern void cpu_hotplug_enable(void);
int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
@@ -148,6 +150,7 @@ extern void cpu_maps_update_done(void);
#else/* CONFIG_SMP */
+#define cpu_hotplug_disable()do { } while (0)
#define cpu_notifier(fn, pri)do { (void)(fn); } while (0)
Breaks alpha allmodconfig because cpu_hotplug_disable() is absent from
vmlinux.
cpu_hotplug_disable() doesn't get compiled unless we've defined
CONFIG_PM_SLEEP_SMP. I cannot begin to imagine what the logic is
behind that!
I'll stick this in there and see what happens.
---
a/include/linux/cpu.h~cpu-hotplug-provide-a-generic-helper-to-disable-enable-cpu-hotplug-fix
+++ a/include/linux/cpu.h
@@ -141,8 +141,6 @@ static inline void unregister_cpu_notifi
}
#endif
-extern void cpu_hotplug_disable(void);
-extern void cpu_hotplug_enable(void);
int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
@@ -150,7 +148,6 @@ extern void cpu_maps_update_done(void);
#else /* CONFIG_SMP */
-#define cpu_hotplug_disable() do { } while (0)
#define cpu_notifier(fn, pri) do { (void)(fn); } while (0)
static inline int register_cpu_notifier(struct notifier_block *nb)
@@ -171,6 +168,15 @@ static inline void cpu_maps_update_done(
}
#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_PM_SLEEP_SMP
+extern void cpu_hotplug_enable(void);
+extern void cpu_hotplug_disable(void);
+#else
+#define cpu_hotplug_enable() do { } while (0)
+#define cpu_hotplug_disable() do { } while (0)
+#endif
+
extern struct bus_type cpu_subsys;
#ifdef CONFIG_HOTPLUG_CPU
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[PATCH -v8 01/11] CPU hotplug: Provide a generic helper to disable/enable CPU hotplug
From: "Srivatsa S. Bhat"
There are instances in the kernel where we would like to disable
CPU hotplug (from sysfs) during some important operation. Today
the freezer code depends on this and the code to do it was kinda
tailor-made for that.
Restructure the code and make it generic enough to be useful for
other usecases too.
Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Robin Holt
To: Andrew Morton
Cc: H. Peter Anvin
Cc: Russ Anderson
Cc: Robin Holt
Cc: Russell King
Cc: Guan Xuetao
Cc: Linux Kernel Mailing List
Cc: the arch/x86 maintainers
Cc: Arm Mailing List
Cc:
---
Changes since -v6:
- Added a #define for non-hotplug case.
---
include/linux/cpu.h | 3 +++
kernel/cpu.c| 27 +--
2 files changed, 12 insertions(+), 18 deletions(-)
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index c6f6e08..3e450c0 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -141,6 +141,8 @@ static inline void unregister_cpu_notifier(struct
notifier_block *nb)
}
#endif
+extern void cpu_hotplug_disable(void);
+extern void cpu_hotplug_enable(void);
int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
@@ -148,6 +150,7 @@ extern void cpu_maps_update_done(void);
#else /* CONFIG_SMP */
+#define cpu_hotplug_disable() do { } while (0)
#define cpu_notifier(fn, pri) do { (void)(fn); } while (0)
static inline int register_cpu_notifier(struct notifier_block *nb)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index b5e4ab2..28769f5 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -541,29 +541,20 @@ static int __init alloc_frozen_cpus(void)
core_initcall(alloc_frozen_cpus);
/*
- * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU
- * hotplug when tasks are about to be frozen. Also, don't allow the freezer
- * to continue until any currently running CPU hotplug operation gets
- * completed.
- * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the
- * 'cpu_add_remove_lock'. And this same lock is also taken by the regular
- * CPU hotplug path and released only after it is complete. Thus, we
- * (and hence the freezer) will block here until any currently running CPU
- * hotplug operation gets completed.
+ * Wait for currently running CPU hotplug operations to complete (if any) and
+ * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
+ * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
+ * hotplug path before performing hotplug operations. So acquiring that lock
+ * guarantees mutual exclusion from any currently running hotplug operations.
*/
-void cpu_hotplug_disable_before_freeze(void)
+void cpu_hotplug_disable(void)
{
cpu_maps_update_begin();
cpu_hotplug_disabled = 1;
cpu_maps_update_done();
}
-
-/*
- * When tasks have been thawed, re-enable regular CPU hotplug (which had been
- * disabled while beginning to freeze tasks).
- */
-void cpu_hotplug_enable_after_thaw(void)
+void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
cpu_hotplug_disabled = 0;
@@ -589,12 +580,12 @@ cpu_hotplug_pm_callback(struct notifier_block *nb,
case PM_SUSPEND_PREPARE:
case PM_HIBERNATION_PREPARE:
- cpu_hotplug_disable_before_freeze();
+ cpu_hotplug_disable();
break;
case PM_POST_SUSPEND:
case PM_POST_HIBERNATION:
- cpu_hotplug_enable_after_thaw();
+ cpu_hotplug_enable();
break;
default:
--
1.8.2.1
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