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authorJason Baron <jbaron@redhat.com>2008-02-28 11:33:03 -0500
committerRusty Russell <rusty@rustcorp.com.au>2008-07-28 12:16:28 +1000
commit5c2aed622571ac7c3c6ec182d6d3c318e4b45c8b (patch)
tree0a3b422b16cd0725eebbe5047fd5482583279d8a
parent15bba37d62351749c3915add81f673b256952ee1 (diff)
stop_machine: add ALL_CPUS option
-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
-rw-r--r--include/linux/stop_machine.h8
-rw-r--r--kernel/stop_machine.c32
2 files changed, 32 insertions, 8 deletions
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index 5bfc553bdb21..18af011c13af 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -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
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 738b411ff2d3..a473bd0cb71b 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -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;
+ mutex_lock(&stopmachine_mutex);
+
smdata.fn = fn;
smdata.data = data;
+ smdata.run_all = (cpu == ALL_CPUS) ? 1 : 0;
init_completion(&smdata.done);
- mutex_lock(&stopmachine_mutex);
+ 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");