Re: [PATCH 3/4] cpu: export cpu hotplug disable/enable functions as global functions

On 08/07/2012 11:21 PM, Kumar Gala wrote:

On Aug 7, 2012, at 3:43 AM, Zhao Chenhui wrote:

quoted

The cpufreq driver of mpc85xx will disable/enable cpu hotplug temporarily.
Therefore, the related functions should be exported.

Signed-off-by: Zhao Chenhui <redacted>
---
include/linux/cpu.h |    4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

Rafael, Srivatsa,

Wanted to get your ack on export these functions for direct calling by arch code.

Why not just use get_online_cpus()/put_online_cpus()?

In the case of suspend/resume/hibernation, we had introduced these CPU hotplug disable
functions because we would end up doing CPU hotplug ourselves, further down the path.
So if we did a get_online_cpus(), we would end up deadlocking ourselves. Whereas, the
patch 4/4 looks like a straightforward case of wanting to simply disable CPU hotplug..
I don't see where you are doing CPU hotplug yourself in the path. So IMO, just
get/put_online_cpus() should do.

Regards,
Srivatsa S. Bhat

quoted

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index ce7a074..df8f73d 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h

@@ -146,6 +146,8 @@ void notify_cpu_starting(unsigned int cpu);

extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);

+extern void cpu_hotplug_disable_before_freeze(void);
+extern void cpu_hotplug_enable_after_thaw(void);
#else	/* CONFIG_SMP */

#define cpu_notifier(fn, pri)	do { (void)(fn); } while (0)

@@ -167,6 +169,8 @@ static inline void cpu_maps_update_done(void)

{
}

+static inline void cpu_hotplug_disable_before_freeze(void)	{}
+static inline void cpu_hotplug_enable_after_thaw(void)	{}
#endif /* CONFIG_SMP */
extern struct bus_type cpu_subsys;

-- 
1.6.4.1