1 files changed, 44 insertions, 35 deletions

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index a1503a027..6df9a83e2 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -24,8 +24,8 @@ struct rb_page {
 static int wakeup_interval = 100;
 
 static int reader_finish;
-static struct completion read_start;
-static struct completion read_done;
+static DECLARE_COMPLETION(read_start);
+static DECLARE_COMPLETION(read_done);
 
 static struct ring_buffer *buffer;
 static struct task_struct *producer;
@@ -60,12 +60,12 @@ MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
 
 static int read_events;
 
-static int kill_test;
+static int test_error;
 
-#define KILL_TEST()				\
+#define TEST_ERROR()				\
 	do {					\
-		if (!kill_test) {		\
-			kill_test = 1;		\
+		if (!test_error) {		\
+			test_error = 1;		\
 			WARN_ON(1);		\
 		}				\
 	} while (0)
@@ -75,6 +75,11 @@ enum event_status {
 	EVENT_DROPPED,
 };
 
+static bool break_test(void)
+{
+	return test_error || kthread_should_stop();
+}
+
 static enum event_status read_event(int cpu)
 {
 	struct ring_buffer_event *event;
@@ -87,7 +92,7 @@ static enum event_status read_event(int cpu)
 
 	entry = ring_buffer_event_data(event);
 	if (*entry != cpu) {
-		KILL_TEST();
+		TEST_ERROR();
 		return EVENT_DROPPED;
 	}
 
@@ -115,10 +120,10 @@ static enum event_status read_page(int cpu)
 		rpage = bpage;
 		/* The commit may have missed event flags set, clear them */
 		commit = local_read(&rpage->commit) & 0xfffff;
-		for (i = 0; i < commit && !kill_test; i += inc) {
+		for (i = 0; i < commit && !test_error ; i += inc) {
 
 			if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
-				KILL_TEST();
+				TEST_ERROR();
 				break;
 			}
 
@@ -128,7 +133,7 @@ static enum event_status read_page(int cpu)
 			case RINGBUF_TYPE_PADDING:
 				/* failed writes may be discarded events */
 				if (!event->time_delta)
-					KILL_TEST();
+					TEST_ERROR();
 				inc = event->array[0] + 4;
 				break;
 			case RINGBUF_TYPE_TIME_EXTEND:
@@ -137,12 +142,12 @@ static enum event_status read_page(int cpu)
 			case 0:
 				entry = ring_buffer_event_data(event);
 				if (*entry != cpu) {
-					KILL_TEST();
+					TEST_ERROR();
 					break;
 				}
 				read++;
 				if (!event->array[0]) {
-					KILL_TEST();
+					TEST_ERROR();
 					break;
 				}
 				inc = event->array[0] + 4;
@@ -150,17 +155,17 @@ static enum event_status read_page(int cpu)
 			default:
 				entry = ring_buffer_event_data(event);
 				if (*entry != cpu) {
-					KILL_TEST();
+					TEST_ERROR();
 					break;
 				}
 				read++;
 				inc = ((event->type_len + 1) * 4);
 			}
-			if (kill_test)
+			if (test_error)
 				break;
 
 			if (inc <= 0) {
-				KILL_TEST();
+				TEST_ERROR();
 				break;
 			}
 		}
@@ -178,10 +183,14 @@ static void ring_buffer_consumer(void)
 	read_events ^= 1;
 
 	read = 0;
-	while (!reader_finish && !kill_test) {
-		int found;
+	/*
+	 * Continue running until the producer specifically asks to stop
+	 * and is ready for the completion.
+	 */
+	while (!READ_ONCE(reader_finish)) {
+		int found = 1;
 
-		do {
+		while (found && !test_error) {
 			int cpu;
 
 			found = 0;
@@ -193,19 +202,25 @@ static void ring_buffer_consumer(void)
 				else
 					stat = read_page(cpu);
 
-				if (kill_test)
+				if (test_error)
 					break;
+
 				if (stat == EVENT_FOUND)
 					found = 1;
+
 			}
-		} while (found && !kill_test);
+		}
 
+		/* Wait till the producer wakes us up when there is more data
+		 * available or when the producer wants us to finish reading.
+		 */
 		set_current_state(TASK_INTERRUPTIBLE);
 		if (reader_finish)
 			break;
 
 		schedule();
 	}
+	__set_current_state(TASK_RUNNING);
 	reader_finish = 0;
 	complete(&read_done);
 }
@@ -263,10 +278,7 @@ static void ring_buffer_producer(void)
 		if (cnt % wakeup_interval)
 			cond_resched();
 #endif
-		if (kthread_should_stop())
-			kill_test = 1;
-
-	} while (ktime_before(end_time, timeout) && !kill_test);
+	} while (ktime_before(end_time, timeout) && !break_test());
 	trace_printk("End ring buffer hammer\n");
 
 	if (consumer) {
@@ -276,8 +288,6 @@ static void ring_buffer_producer(void)
 		/* the completions must be visible before the finish var */
 		smp_wmb();
 		reader_finish = 1;
-		/* finish var visible before waking up the consumer */
-		smp_wmb();
 		wake_up_process(consumer);
 		wait_for_completion(&read_done);
 	}
@@ -287,7 +297,7 @@ static void ring_buffer_producer(void)
 	entries = ring_buffer_entries(buffer);
 	overruns = ring_buffer_overruns(buffer);
 
-	if (kill_test && !kthread_should_stop())
+	if (test_error)
 		trace_printk("ERROR!\n");
 
 	if (!disable_reader) {
@@ -368,15 +378,14 @@ static void wait_to_die(void)
 
 static int ring_buffer_consumer_thread(void *arg)
 {
-	while (!kthread_should_stop() && !kill_test) {
+	while (!break_test()) {
 		complete(&read_start);
 
 		ring_buffer_consumer();
 
 		set_current_state(TASK_INTERRUPTIBLE);
-		if (kthread_should_stop() || kill_test)
+		if (break_test())
 			break;
-
 		schedule();
 	}
 	__set_current_state(TASK_RUNNING);
@@ -389,27 +398,27 @@ static int ring_buffer_consumer_thread(void *arg)
 
 static int ring_buffer_producer_thread(void *arg)
 {
-	init_completion(&read_start);
-
-	while (!kthread_should_stop() && !kill_test) {
+	while (!break_test()) {
 		ring_buffer_reset(buffer);
 
 		if (consumer) {
-			smp_wmb();
 			wake_up_process(consumer);
 			wait_for_completion(&read_start);
 		}
 
 		ring_buffer_producer();
-		if (kill_test)
+		if (break_test())
 			goto out_kill;
 
 		trace_printk("Sleeping for 10 secs\n");
 		set_current_state(TASK_INTERRUPTIBLE);
+		if (break_test())
+			goto out_kill;
 		schedule_timeout(HZ * SLEEP_TIME);
 	}
 
 out_kill:
+	__set_current_state(TASK_RUNNING);
 	if (!kthread_should_stop())
 		wait_to_die();