stop_machine: make stop_machine safe and efficient to call early
Make stop_machine() safe to call early in boot, before SMP has been set up, by simply calling the callback function directly if there's only one CPU online. [ Fixes from AKPM: - add comment - local_irq_flags, not save_flags - also call hard_irq_disable() for systems which need it Tejun suggested using an explicit flag rather than just looking at the online cpu count. ] Cc: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Steven Rostedt <rostedt@goodmis.org> Acked-by: Tejun Heo <htejun@gmail.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
aaaa287b89
commit
f445027e4e
@ -41,6 +41,7 @@ struct cpu_stopper {
|
|||||||
};
|
};
|
||||||
|
|
||||||
static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
|
static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
|
||||||
|
static bool stop_machine_initialized = false;
|
||||||
|
|
||||||
static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
|
static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
|
||||||
{
|
{
|
||||||
@ -386,6 +387,8 @@ static int __init cpu_stop_init(void)
|
|||||||
cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_ONLINE, bcpu);
|
cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_ONLINE, bcpu);
|
||||||
register_cpu_notifier(&cpu_stop_cpu_notifier);
|
register_cpu_notifier(&cpu_stop_cpu_notifier);
|
||||||
|
|
||||||
|
stop_machine_initialized = true;
|
||||||
|
|
||||||
return 0;
|
return 0;
|
||||||
}
|
}
|
||||||
early_initcall(cpu_stop_init);
|
early_initcall(cpu_stop_init);
|
||||||
@ -485,6 +488,25 @@ int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus)
|
|||||||
.num_threads = num_online_cpus(),
|
.num_threads = num_online_cpus(),
|
||||||
.active_cpus = cpus };
|
.active_cpus = cpus };
|
||||||
|
|
||||||
|
if (!stop_machine_initialized) {
|
||||||
|
/*
|
||||||
|
* Handle the case where stop_machine() is called
|
||||||
|
* early in boot before stop_machine() has been
|
||||||
|
* initialized.
|
||||||
|
*/
|
||||||
|
unsigned long flags;
|
||||||
|
int ret;
|
||||||
|
|
||||||
|
WARN_ON_ONCE(smdata.num_threads != 1);
|
||||||
|
|
||||||
|
local_irq_save(flags);
|
||||||
|
hard_irq_disable();
|
||||||
|
ret = (*fn)(data);
|
||||||
|
local_irq_restore(flags);
|
||||||
|
|
||||||
|
return ret;
|
||||||
|
}
|
||||||
|
|
||||||
/* Set the initial state and stop all online cpus. */
|
/* Set the initial state and stop all online cpus. */
|
||||||
set_state(&smdata, STOPMACHINE_PREPARE);
|
set_state(&smdata, STOPMACHINE_PREPARE);
|
||||||
return stop_cpus(cpu_online_mask, stop_machine_cpu_stop, &smdata);
|
return stop_cpus(cpu_online_mask, stop_machine_cpu_stop, &smdata);
|
||||||
|
Loading…
Reference in New Issue
Block a user