On Wed, May 24, 2017 at 10:15:12AM +0200, Thomas Gleixner wrote: > The counting 'rwsem' hackery of get|put_online_cpus() is going to be > replaced by percpu rwsem. > > Rename the functions to make it clear that it's locking and not some > refcount style interface. These new functions will be used for the > preparatory patches which make the code ready for the percpu rwsem > conversion. > > Rename all instances in the cpu hotplug code while at it. > > Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Paul E. McKenney <[email protected]> > --- > include/linux/cpu.h | 32 ++++++++++++++++++-------------- > kernel/cpu.c | 36 ++++++++++++++++++------------------ > 2 files changed, 36 insertions(+), 32 deletions(-) > > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -99,26 +99,30 @@ static inline void cpu_maps_update_done( > extern struct bus_type cpu_subsys; > > #ifdef CONFIG_HOTPLUG_CPU > -/* Stop CPUs going up and down. */ > - > -extern void cpu_hotplug_begin(void); > -extern void cpu_hotplug_done(void); > -extern void get_online_cpus(void); > -extern void put_online_cpus(void); > +extern void cpus_write_lock(void); > +extern void cpus_write_unlock(void); > +extern void cpus_read_lock(void); > +extern void cpus_read_unlock(void); > extern void cpu_hotplug_disable(void); > extern void cpu_hotplug_enable(void); > void clear_tasks_mm_cpumask(int cpu); > int cpu_down(unsigned int cpu); > > -#else /* CONFIG_HOTPLUG_CPU */ > +#else /* CONFIG_HOTPLUG_CPU */ > + > +static inline void cpus_write_lock(void) { } > +static inline void cpus_write_unlock(void) { } > +static inline void cpus_read_lock(void) { } > +static inline void cpus_read_unlock(void) { } > +static inline void cpu_hotplug_disable(void) { } > +static inline void cpu_hotplug_enable(void) { } > +#endif /* !CONFIG_HOTPLUG_CPU */ > > -static inline void cpu_hotplug_begin(void) {} > -static inline void cpu_hotplug_done(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) > -#endif /* CONFIG_HOTPLUG_CPU */ > +/* Wrappers which go away once all code is converted */ > +static inline void cpu_hotplug_begin(void) { cpus_write_lock(); } > +static inline void cpu_hotplug_done(void) { cpus_write_unlock(); } > +static inline void get_online_cpus(void) { cpus_read_lock(); } > +static inline void put_online_cpus(void) { cpus_read_unlock(); } > > #ifdef CONFIG_PM_SLEEP_SMP > extern int freeze_secondary_cpus(int primary); > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -235,7 +235,7 @@ static struct { > #define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map) > > > -void get_online_cpus(void) > +void cpus_read_lock(void) > { > might_sleep(); > if (cpu_hotplug.active_writer == current) > @@ -245,9 +245,9 @@ void get_online_cpus(void) > atomic_inc(&cpu_hotplug.refcount); > mutex_unlock(&cpu_hotplug.lock); > } > -EXPORT_SYMBOL_GPL(get_online_cpus); > +EXPORT_SYMBOL_GPL(cpus_read_lock); > > -void put_online_cpus(void) > +void cpus_read_unlock(void) > { > int refcount; > > @@ -264,7 +264,7 @@ void put_online_cpus(void) > cpuhp_lock_release(); > > } > -EXPORT_SYMBOL_GPL(put_online_cpus); > +EXPORT_SYMBOL_GPL(cpus_read_unlock); > > /* > * This ensures that the hotplug operation can begin only when the > @@ -288,7 +288,7 @@ EXPORT_SYMBOL_GPL(put_online_cpus); > * get_online_cpus() not an api which is called all that often. > * > */ > -void cpu_hotplug_begin(void) > +void cpus_write_lock(void) > { > DEFINE_WAIT(wait); > > @@ -306,7 +306,7 @@ void cpu_hotplug_begin(void) > finish_wait(&cpu_hotplug.wq, &wait); > } > > -void cpu_hotplug_done(void) > +void cpus_write_unlock(void) > { > cpu_hotplug.active_writer = NULL; > mutex_unlock(&cpu_hotplug.lock); > @@ -773,7 +773,7 @@ static int __ref _cpu_down(unsigned int > if (!cpu_present(cpu)) > return -EINVAL; > > - cpu_hotplug_begin(); > + cpus_write_lock(); > > cpuhp_tasks_frozen = tasks_frozen; > > @@ -811,7 +811,7 @@ static int __ref _cpu_down(unsigned int > } > > out: > - cpu_hotplug_done(); > + cpus_write_unlock(); > return ret; > } > > @@ -893,7 +893,7 @@ static int _cpu_up(unsigned int cpu, int > struct task_struct *idle; > int ret = 0; > > - cpu_hotplug_begin(); > + cpus_write_lock(); > > if (!cpu_present(cpu)) { > ret = -EINVAL; > @@ -941,7 +941,7 @@ static int _cpu_up(unsigned int cpu, int > target = min((int)target, CPUHP_BRINGUP_CPU); > ret = cpuhp_up_callbacks(cpu, st, target); > out: > - cpu_hotplug_done(); > + cpus_write_unlock(); > return ret; > } > > @@ -1424,7 +1424,7 @@ int __cpuhp_state_add_instance(enum cpuh > if (sp->multi_instance == false) > return -EINVAL; > > - get_online_cpus(); > + cpus_read_lock(); > mutex_lock(&cpuhp_state_mutex); > > if (!invoke || !sp->startup.multi) > @@ -1453,7 +1453,7 @@ int __cpuhp_state_add_instance(enum cpuh > hlist_add_head(node, &sp->list); > unlock: > mutex_unlock(&cpuhp_state_mutex); > - put_online_cpus(); > + cpus_read_unlock(); > return ret; > } > EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); > @@ -1486,7 +1486,7 @@ int __cpuhp_setup_state(enum cpuhp_state > if (cpuhp_cb_check(state) || !name) > return -EINVAL; > > - get_online_cpus(); > + cpus_read_lock(); > mutex_lock(&cpuhp_state_mutex); > > ret = cpuhp_store_callbacks(state, name, startup, teardown, > @@ -1522,7 +1522,7 @@ int __cpuhp_setup_state(enum cpuhp_state > } > out: > mutex_unlock(&cpuhp_state_mutex); > - put_online_cpus(); > + cpus_read_unlock(); > /* > * If the requested state is CPUHP_AP_ONLINE_DYN, return the > * dynamically allocated state in case of success. > @@ -1544,7 +1544,7 @@ int __cpuhp_state_remove_instance(enum c > if (!sp->multi_instance) > return -EINVAL; > > - get_online_cpus(); > + cpus_read_lock(); > mutex_lock(&cpuhp_state_mutex); > > if (!invoke || !cpuhp_get_teardown_cb(state)) > @@ -1565,7 +1565,7 @@ int __cpuhp_state_remove_instance(enum c > remove: > hlist_del(node); > mutex_unlock(&cpuhp_state_mutex); > - put_online_cpus(); > + cpus_read_unlock(); > > return 0; > } > @@ -1587,7 +1587,7 @@ void __cpuhp_remove_state(enum cpuhp_sta > > BUG_ON(cpuhp_cb_check(state)); > > - get_online_cpus(); > + cpus_read_lock(); > > mutex_lock(&cpuhp_state_mutex); > if (sp->multi_instance) { > @@ -1615,7 +1615,7 @@ void __cpuhp_remove_state(enum cpuhp_sta > remove: > cpuhp_store_callbacks(state, NULL, NULL, NULL, false); > mutex_unlock(&cpuhp_state_mutex); > - put_online_cpus(); > + cpus_read_unlock(); > } > EXPORT_SYMBOL(__cpuhp_remove_state); > > >
