| Message ID | 20130509150121.8c3ef60b2fc748ce542a1a52@linux-foundation.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thursday, May 09, 2013 03:01:21 PM Andrew Morton wrote: > On Tue, 7 May 2013 09:39:45 -0500 Robin Holt <holt@sgi.com> wrote: > > > From: "Srivatsa S. Bhat" <srivatsa.bhat@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
On Fri, 10 May 2013 13:11:51 +0200 "Rafael J. Wysocki" <rjw@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.
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" <rjw@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.bhat@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
--- 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