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author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2008-12-22 12:36:30 +0100 |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2009-01-05 08:40:14 +1030 |
commit | 9ea09af3bd3090e8349ca2899ca2011bd94cda85 (patch) | |
tree | 36396347bb750a6aecb0771cfebf9887aaaae492 /include/linux | |
parent | c298be74492bece102f3379d14015638f1fd1fac (diff) | |
download | op-kernel-dev-9ea09af3bd3090e8349ca2899ca2011bd94cda85.zip op-kernel-dev-9ea09af3bd3090e8349ca2899ca2011bd94cda85.tar.gz |
stop_machine: introduce stop_machine_create/destroy.
Introduce stop_machine_create/destroy. With this interface subsystems
that need a non-failing stop_machine environment can create the
stop_machine machine threads before actually calling stop_machine.
When the threads aren't needed anymore they can be killed with
stop_machine_destroy again.
When stop_machine gets called and the threads aren't present they
will be created and destroyed automatically. This restores the old
behaviour of stop_machine.
This patch also converts cpu hotplug to the new interface since it
is special: cpu_down calls __stop_machine instead of stop_machine.
However the kstop threads will only be created when stop_machine
gets called.
Changing the code so that the threads would be created automatically
on __stop_machine is currently not possible: when __stop_machine gets
called we hold cpu_add_remove_lock, which is the same lock that
create_rt_workqueue would take. So the workqueue needs to be created
before the cpu hotplug code locks cpu_add_remove_lock.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/stop_machine.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 74d59a6..baba3a2 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -35,6 +35,24 @@ int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); * won't come or go while it's being called. Used by hotplug cpu. */ int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); + +/** + * stop_machine_create: create all stop_machine threads + * + * Description: This causes all stop_machine threads to be created before + * stop_machine actually gets called. This can be used by subsystems that + * need a non failing stop_machine infrastructure. + */ +int stop_machine_create(void); + +/** + * stop_machine_destroy: destroy all stop_machine threads + * + * Description: This causes all stop_machine threads which were created with + * stop_machine_create to be destroyed again. + */ +void stop_machine_destroy(void); + #else static inline int stop_machine(int (*fn)(void *), void *data, @@ -46,5 +64,9 @@ static inline int stop_machine(int (*fn)(void *), void *data, local_irq_enable(); return ret; } + +static inline int stop_machine_create(void) { return 0; } +static inline void stop_machine_destroy(void) { } + #endif /* CONFIG_SMP */ #endif /* _LINUX_STOP_MACHINE */ |