@@ -9,6 +9,7 @@
* published by the Free Software Foundation.
*/
+#include <linux/atomic.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -25,6 +26,7 @@
#include <linux/notifier.h>
#include <linux/mm.h>
#include <linux/mutex.h>
+#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/irqchip/arm-gic.h>
@@ -224,10 +226,13 @@ static int bL_switch_to(unsigned int new_cluster_id)
}
struct bL_thread {
+ spinlock_t lock;
struct task_struct *task;
wait_queue_head_t wq;
int wanted_cluster;
struct completion started;
+ bL_switch_completion_handler completer;
+ void *completer_cookie;
};
static struct bL_thread bL_threads[NR_CPUS];
@@ -237,6 +242,8 @@ static int bL_switcher_thread(void *arg)
struct bL_thread *t = arg;
struct sched_param param = { .sched_priority = 1 };
int cluster;
+ bL_switch_completion_handler completer;
+ void *completer_cookie;
sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m);
complete(&t->started);
@@ -247,9 +254,21 @@ static int bL_switcher_thread(void *arg)
wait_event_interruptible(t->wq,
t->wanted_cluster != -1 ||
kthread_should_stop());
- cluster = xchg(&t->wanted_cluster, -1);
- if (cluster != -1)
+
+ spin_lock(&t->lock);
+ cluster = t->wanted_cluster;
+ completer = t->completer;
+ completer_cookie = t->completer_cookie;
+ t->wanted_cluster = -1;
+ t->completer = NULL;
+ spin_unlock(&t->lock);
+
+ if (cluster != -1) {
bL_switch_to(cluster);
+
+ if (completer)
+ completer(completer_cookie);
+ }
} while (!kthread_should_stop());
return 0;
@@ -270,16 +289,30 @@ static struct task_struct *bL_switcher_thread_create(int cpu, void *arg)
}
/*
- * bL_switch_request - Switch to a specific cluster for the given CPU
+ * bL_switch_request_cb - Switch to a specific cluster for the given CPU,
+ * with completion notification via a callback
*
* @cpu: the CPU to switch
* @new_cluster_id: the ID of the cluster to switch to.
+ * @completer: switch completion callback. if non-NULL,
+ * @completer(@completer_cookie) will be called on completion of
+ * the switch, in non-atomic context.
+ * @completer_cookie: opaque context argument for @completer.
*
* This function causes a cluster switch on the given CPU by waking up
* the appropriate switcher thread. This function may or may not return
* before the switch has occurred.
+ *
+ * If a @completer callback function is supplied, it will be called when
+ * the switch is complete. This can be used to determine asynchronously
+ * when the switch is complete, regardless of when bL_switch_request()
+ * returns. When @completer is supplied, no new switch request is permitted
+ * for the affected CPU until after the switch is complete, and @completer
+ * has returned.
*/
-int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id)
+int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id,
+ bL_switch_completion_handler completer,
+ void *completer_cookie)
{
struct bL_thread *t;
@@ -289,16 +322,25 @@ int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id)
}
t = &bL_threads[cpu];
+
if (IS_ERR(t->task))
return PTR_ERR(t->task);
if (!t->task)
return -ESRCH;
+ spin_lock(&t->lock);
+ if (t->completer) {
+ spin_unlock(&t->lock);
+ return -EBUSY;
+ }
+ t->completer = completer;
+ t->completer_cookie = completer_cookie;
t->wanted_cluster = new_cluster_id;
+ spin_unlock(&t->lock);
wake_up(&t->wq);
return 0;
}
-EXPORT_SYMBOL_GPL(bL_switch_request);
+EXPORT_SYMBOL_GPL(bL_switch_request_cb);
/*
* Activation and configuration code.
@@ -460,6 +502,7 @@ static int bL_switcher_enable(void)
for_each_online_cpu(cpu) {
struct bL_thread *t = &bL_threads[cpu];
+ spin_lock_init(&t->lock);
init_waitqueue_head(&t->wq);
init_completion(&t->started);
t->wanted_cluster = -1;
@@ -15,7 +15,15 @@
#include <linux/compiler.h>
#include <linux/types.h>
-int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id);
+typedef void (*bL_switch_completion_handler)(void *cookie);
+
+int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id,
+ bL_switch_completion_handler completer,
+ void *completer_cookie);
+static inline int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id)
+{
+ return bL_switch_request_cb(cpu, new_cluster_id, NULL, NULL);
+}
/*
* Register here to be notified about runtime enabling/disabling of