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stop_machine: add ALL_CPUS option

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-allow stop_mahcine_run() to call a function on all cpus. Calling
 stop_machine_run() with a 'ALL_CPUS' invokes this new behavior.
 stop_machine_run() proceeds as normal until the calling cpu has
 invoked 'fn'. Then, we tell all the other cpus to call 'fn'.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
CC: Adrian Bunk <bunk@stusta.de>
CC: Andi Kleen <andi@firstfloor.org>
CC: Alexey Dobriyan <adobriyan@gmail.com>
CC: Christoph Hellwig <hch@infradead.org>
CC: mingo@elte.hu
CC: akpm@osdl.org
This commit is contained in:
Jason Baron 2008-02-28 11:33:03 -05:00 committed by Rusty Russell
parent 15bba37d62
commit 5c2aed6225
2 changed files with 35 additions and 11 deletions
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8
include/linux/stop_machine.h
View file

@ -8,11 +8,17 @@
#include <asm/system.h>
#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
#define ALL_CPUS ~0U
/**
* stop_machine_run: freeze the machine on all CPUs and run this function
* @fn: the function to run
* @data: the data ptr for the @fn()
* @cpu: the cpu to run @fn() on (or any, if @cpu == NR_CPUS.
* @cpu: if @cpu == n, run @fn() on cpu n
* if @cpu == NR_CPUS, run @fn() on any cpu
* if @cpu == ALL_CPUS, run @fn() first on the calling cpu, and then
* concurrently on all the other cpus
*
* Description: This causes a thread to be scheduled on every other cpu,
* each of which disables interrupts, and finally interrupts are disabled

38
kernel/stop_machine.c
View file

@ -22,9 +22,17 @@ enum stopmachine_state {
STOPMACHINE_WAIT,
STOPMACHINE_PREPARE,
STOPMACHINE_DISABLE_IRQ,
STOPMACHINE_RUN,
STOPMACHINE_EXIT,
};
struct stop_machine_data {
int (*fn)(void *);
void *data;
struct completion done;
int run_all;
} smdata;
static enum stopmachine_state stopmachine_state;
static unsigned int stopmachine_num_threads;
static atomic_t stopmachine_thread_ack;
@ -33,6 +41,7 @@ static int stopmachine(void *cpu)
{
int irqs_disabled = 0;
int prepared = 0;
int ran = 0;
cpumask_of_cpu_ptr(cpumask, (int)(long)cpu);
set_cpus_allowed_ptr(current, cpumask);
@ -58,6 +67,11 @@ static int stopmachine(void *cpu)
prepared = 1;
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
} else if (stopmachine_state == STOPMACHINE_RUN && !ran) {
smdata.fn(smdata.data);
ran = 1;
smp_mb(); /* Must read state first. */
atomic_inc(&stopmachine_thread_ack);
}
/* Yield in first stage: migration threads need to
* help our sisters onto their CPUs. */
@ -136,11 +150,10 @@ static void restart_machine(void)
preempt_enable_no_resched();
}
struct stop_machine_data {
int (*fn)(void *);
void *data;
struct completion done;
};
static void run_other_cpus(void)
{
stopmachine_set_state(STOPMACHINE_RUN);
}
static int do_stop(void *_smdata)
{
@ -150,6 +163,8 @@ static int do_stop(void *_smdata)
ret = stop_machine();
if (ret == 0) {
ret = smdata->fn(smdata->data);
if (smdata->run_all)
run_other_cpus();
restart_machine();
}
@ -173,14 +188,17 @@ struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
struct stop_machine_data smdata;
struct task_struct *p;
smdata.fn = fn;
smdata.data = data;
init_completion(&smdata.done);
mutex_lock(&stopmachine_mutex);
smdata.fn = fn;
smdata.data = data;
smdata.run_all = (cpu == ALL_CPUS) ? 1 : 0;
init_completion(&smdata.done);
smp_wmb(); /* make sure other cpus see smdata updates */
/* If they don't care which CPU fn runs on, bind to any online one. */
if (cpu == NR_CPUS)
if (cpu == NR_CPUS || cpu == ALL_CPUS)
cpu = raw_smp_processor_id();
p = kthread_create(do_stop, &smdata, "kstopmachine");