1 files changed, 9 insertions, 26 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index c634868c292..925f629658d 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -543,7 +543,7 @@ static void rb_wake_up_waiters(struct irq_work *work)
  * as data is added to any of the @buffer's cpu buffers. Otherwise
  * it will wait for data to be added to a specific cpu buffer.
  */
-void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
+int ring_buffer_wait(struct ring_buffer *buffer, int cpu)
 {
 	struct ring_buffer_per_cpu *cpu_buffer;
 	DEFINE_WAIT(wait);
@@ -557,6 +557,8 @@ void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
 	if (cpu == RING_BUFFER_ALL_CPUS)
 		work = &buffer->irq_work;
 	else {
+		if (!cpumask_test_cpu(cpu, buffer->cpumask))
+			return -ENODEV;
 		cpu_buffer = buffer->buffers[cpu];
 		work = &cpu_buffer->irq_work;
 	}
@@ -591,6 +593,7 @@ void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
 		schedule();
 
 	finish_wait(&work->waiters, &wait);
+	return 0;
 }
 
 /**
@@ -613,10 +616,6 @@ int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
 	struct ring_buffer_per_cpu *cpu_buffer;
 	struct rb_irq_work *work;
 
-	if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||
-	    (cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))
-		return POLLIN | POLLRDNORM;
-
 	if (cpu == RING_BUFFER_ALL_CPUS)
 		work = &buffer->irq_work;
 	else {
@@ -1690,22 +1689,14 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
 			if (!cpu_buffer->nr_pages_to_update)
 				continue;
 
-			/* The update must run on the CPU that is being updated. */
-			preempt_disable();
-			if (cpu == smp_processor_id() || !cpu_online(cpu)) {
+			/* Can't run something on an offline CPU. */
+			if (!cpu_online(cpu)) {
 				rb_update_pages(cpu_buffer);
 				cpu_buffer->nr_pages_to_update = 0;
 			} else {
-				/*
-				 * Can not disable preemption for schedule_work_on()
-				 * on PREEMPT_RT.
-				 */
-				preempt_enable();
 				schedule_work_on(cpu,
 						&cpu_buffer->update_pages_work);
-				preempt_disable();
 			}
-			preempt_enable();
 		}
 
 		/* wait for all the updates to complete */
@@ -1743,22 +1734,14 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
 
 		get_online_cpus();
 
-		preempt_disable();
-		/* The update must run on the CPU that is being updated. */
-		if (cpu_id == smp_processor_id() || !cpu_online(cpu_id))
+		/* Can't run something on an offline CPU. */
+		if (!cpu_online(cpu_id))
 			rb_update_pages(cpu_buffer);
 		else {
-			/*
-			 * Can not disable preemption for schedule_work_on()
-			 * on PREEMPT_RT.
-			 */
-			preempt_enable();
 			schedule_work_on(cpu_id,
 					 &cpu_buffer->update_pages_work);
 			wait_for_completion(&cpu_buffer->update_done);
-			preempt_disable();
 		}
-		preempt_enable();
 
 		cpu_buffer->nr_pages_to_update = 0;
 		put_online_cpus();
@@ -3776,7 +3759,7 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
 	if (rb_per_cpu_empty(cpu_buffer))
 		return NULL;
 
-	if (iter->head >= local_read(&iter->head_page->page->commit)) {
+	if (iter->head >= rb_page_size(iter->head_page)) {
 		rb_inc_iter(iter);
 		goto again;
 	}