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-rw-r--r--kernel/stop_machine.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 32a6c44d8f78..c530bc5be7cf 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -234,11 +234,13 @@ static void irq_cpu_stop_queue_work(void *arg)
*/
int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg)
{
- int call_cpu;
struct cpu_stop_done done;
struct cpu_stop_work work1, work2;
struct irq_cpu_stop_queue_work_info call_args;
- struct multi_stop_data msdata = {
+ struct multi_stop_data msdata;
+
+ preempt_disable();
+ msdata = (struct multi_stop_data){
.fn = fn,
.data = arg,
.num_threads = 2,
@@ -262,16 +264,30 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
set_state(&msdata, MULTI_STOP_PREPARE);
/*
+ * If we observe both CPUs active we know _cpu_down() cannot yet have
+ * queued its stop_machine works and therefore ours will get executed
+ * first. Or its not either one of our CPUs that's getting unplugged,
+ * in which case we don't care.
+ *
+ * This relies on the stopper workqueues to be FIFO.
+ */
+ if (!cpu_active(cpu1) || !cpu_active(cpu2)) {
+ preempt_enable();
+ return -ENOENT;
+ }
+
+ /*
* Queuing needs to be done by the lowest numbered CPU, to ensure
* that works are always queued in the same order on every CPU.
* This prevents deadlocks.
*/
- call_cpu = min(cpu1, cpu2);
-
- smp_call_function_single(call_cpu, &irq_cpu_stop_queue_work,
+ smp_call_function_single(min(cpu1, cpu2),
+ &irq_cpu_stop_queue_work,
&call_args, 0);
+ preempt_enable();
wait_for_completion(&done.completion);
+
return done.executed ? done.ret : -ENOENT;
}