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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-25 03:53:42 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-25 03:53:42 -0300
commit03dd4cb26d967f9588437b0fc9cc0e8353322bb7 (patch)
treefa581f6dc1c0596391690d1f67eceef3af8246dc /kernel/stop_machine.c
parentd4e493caf788ef44982e131ff9c786546904d934 (diff)
Linux-libre 4.5-gnu
Diffstat (limited to 'kernel/stop_machine.c')
-rw-r--r--kernel/stop_machine.c88
1 files changed, 41 insertions, 47 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index a3bbaee77..a467e6c28 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -28,7 +28,6 @@
*/
struct cpu_stop_done {
atomic_t nr_todo; /* nr left to execute */
- bool executed; /* actually executed? */
int ret; /* collected return value */
struct completion completion; /* fired if nr_todo reaches 0 */
};
@@ -63,14 +62,10 @@ static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
}
/* signal completion unless @done is NULL */
-static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed)
+static void cpu_stop_signal_done(struct cpu_stop_done *done)
{
- if (done) {
- if (executed)
- done->executed = true;
- if (atomic_dec_and_test(&done->nr_todo))
- complete(&done->completion);
- }
+ if (atomic_dec_and_test(&done->nr_todo))
+ complete(&done->completion);
}
static void __cpu_stop_queue_work(struct cpu_stopper *stopper,
@@ -81,17 +76,21 @@ static void __cpu_stop_queue_work(struct cpu_stopper *stopper,
}
/* queue @work to @stopper. if offline, @work is completed immediately */
-static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
+static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
{
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
unsigned long flags;
+ bool enabled;
spin_lock_irqsave(&stopper->lock, flags);
- if (stopper->enabled)
+ enabled = stopper->enabled;
+ if (enabled)
__cpu_stop_queue_work(stopper, work);
- else
- cpu_stop_signal_done(work->done, false);
+ else if (work->done)
+ cpu_stop_signal_done(work->done);
spin_unlock_irqrestore(&stopper->lock, flags);
+
+ return enabled;
}
/**
@@ -124,9 +123,10 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done };
cpu_stop_init_done(&done, 1);
- cpu_stop_queue_work(cpu, &work);
+ if (!cpu_stop_queue_work(cpu, &work))
+ return -ENOENT;
wait_for_completion(&done.completion);
- return done.executed ? done.ret : -ENOENT;
+ return done.ret;
}
/* This controls the threads on each CPU. */
@@ -258,7 +258,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
struct cpu_stop_work work1, work2;
struct multi_stop_data msdata;
- preempt_disable();
msdata = (struct multi_stop_data){
.fn = fn,
.data = arg,
@@ -277,16 +276,11 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
if (cpu1 > cpu2)
swap(cpu1, cpu2);
- if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2)) {
- preempt_enable();
+ if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2))
return -ENOENT;
- }
-
- preempt_enable();
wait_for_completion(&done.completion);
-
- return done.executed ? done.ret : -ENOENT;
+ return done.ret;
}
/**
@@ -302,23 +296,28 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
*
* CONTEXT:
* Don't care.
+ *
+ * RETURNS:
+ * true if cpu_stop_work was queued successfully and @fn will be called,
+ * false otherwise.
*/
-void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
+bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
struct cpu_stop_work *work_buf)
{
*work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, };
- cpu_stop_queue_work(cpu, work_buf);
+ return cpu_stop_queue_work(cpu, work_buf);
}
/* static data for stop_cpus */
static DEFINE_MUTEX(stop_cpus_mutex);
-static void queue_stop_cpus_work(const struct cpumask *cpumask,
+static bool queue_stop_cpus_work(const struct cpumask *cpumask,
cpu_stop_fn_t fn, void *arg,
struct cpu_stop_done *done)
{
struct cpu_stop_work *work;
unsigned int cpu;
+ bool queued = false;
/*
* Disable preemption while queueing to avoid getting
@@ -331,9 +330,12 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask,
work->fn = fn;
work->arg = arg;
work->done = done;
- cpu_stop_queue_work(cpu, work);
+ if (cpu_stop_queue_work(cpu, work))
+ queued = true;
}
lg_global_unlock(&stop_cpus_lock);
+
+ return queued;
}
static int __stop_cpus(const struct cpumask *cpumask,
@@ -342,9 +344,10 @@ static int __stop_cpus(const struct cpumask *cpumask,
struct cpu_stop_done done;
cpu_stop_init_done(&done, cpumask_weight(cpumask));
- queue_stop_cpus_work(cpumask, fn, arg, &done);
+ if (!queue_stop_cpus_work(cpumask, fn, arg, &done))
+ return -ENOENT;
wait_for_completion(&done.completion);
- return done.executed ? done.ret : -ENOENT;
+ return done.ret;
}
/**
@@ -432,7 +435,6 @@ static void cpu_stopper_thread(unsigned int cpu)
{
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
struct cpu_stop_work *work;
- int ret;
repeat:
work = NULL;
@@ -448,23 +450,19 @@ repeat:
cpu_stop_fn_t fn = work->fn;
void *arg = work->arg;
struct cpu_stop_done *done = work->done;
- char ksym_buf[KSYM_NAME_LEN] __maybe_unused;
-
- /* cpu stop callbacks are not allowed to sleep */
- preempt_disable();
+ int ret;
+ /* cpu stop callbacks must not sleep, make in_atomic() == T */
+ preempt_count_inc();
ret = fn(arg);
- if (ret)
- done->ret = ret;
-
- /* restore preemption and check it's still balanced */
- preempt_enable();
+ if (done) {
+ if (ret)
+ done->ret = ret;
+ cpu_stop_signal_done(done);
+ }
+ preempt_count_dec();
WARN_ONCE(preempt_count(),
- "cpu_stop: %s(%p) leaked preempt count\n",
- kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL,
- ksym_buf), arg);
-
- cpu_stop_signal_done(done, true);
+ "cpu_stop: %pf(%p) leaked preempt count\n", fn, arg);
goto repeat;
}
}
@@ -531,8 +529,6 @@ static int __init cpu_stop_init(void)
}
early_initcall(cpu_stop_init);
-#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
-
static int __stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)
{
struct multi_stop_data msdata = {
@@ -630,5 +626,3 @@ int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
mutex_unlock(&stop_cpus_mutex);
return ret ?: done.ret;
}
-
-#endif /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */