1 files changed, 17 insertions, 34 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index c366a0a9ddba..af50d931b020 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1581,19 +1581,6 @@ static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer,
 }
 
 /**
- * rb_check_list - make sure a pointer to a list has the last bits zero
- */
-static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer,
-			 struct list_head *list)
-{
-	if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev))
-		return 1;
-	if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next))
-		return 1;
-	return 0;
-}
-
-/**
  * rb_check_pages - integrity check of buffer pages
  * @cpu_buffer: CPU buffer with pages to test
  *
@@ -1602,36 +1589,27 @@ static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer,
  */
 static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
 {
-	struct list_head *head = cpu_buffer->pages;
-	struct buffer_page *bpage, *tmp;
-
-	/* Reset the head page if it exists */
-	if (cpu_buffer->head_page)
-		rb_set_head_page(cpu_buffer);
-
-	rb_head_page_deactivate(cpu_buffer);
+	struct list_head *head = rb_list_head(cpu_buffer->pages);
+	struct list_head *tmp;
 
-	if (RB_WARN_ON(cpu_buffer, head->next->prev != head))
-		return -1;
-	if (RB_WARN_ON(cpu_buffer, head->prev->next != head))
+	if (RB_WARN_ON(cpu_buffer,
+			rb_list_head(rb_list_head(head->next)->prev) != head))
 		return -1;
 
-	if (rb_check_list(cpu_buffer, head))
+	if (RB_WARN_ON(cpu_buffer,
+			rb_list_head(rb_list_head(head->prev)->next) != head))
 		return -1;
 
-	list_for_each_entry_safe(bpage, tmp, head, list) {
+	for (tmp = rb_list_head(head->next); tmp != head; tmp = rb_list_head(tmp->next)) {
 		if (RB_WARN_ON(cpu_buffer,
-			       bpage->list.next->prev != &bpage->list))
+				rb_list_head(rb_list_head(tmp->next)->prev) != tmp))
 			return -1;
+
 		if (RB_WARN_ON(cpu_buffer,
-			       bpage->list.prev->next != &bpage->list))
-			return -1;
-		if (rb_check_list(cpu_buffer, &bpage->list))
+				rb_list_head(rb_list_head(tmp->prev)->next) != tmp))
 			return -1;
 	}
 
-	rb_head_page_activate(cpu_buffer);
-
 	return 0;
 }
 
@@ -2886,7 +2864,7 @@ rb_check_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
 		  sched_clock_stable() ? "" :
 		  "If you just came from a suspend/resume,\n"
 		  "please switch to the trace global clock:\n"
-		  "  echo global > /sys/kernel/debug/tracing/trace_clock\n"
+		  "  echo global > /sys/kernel/tracing/trace_clock\n"
 		  "or add trace_clock=global to the kernel command line\n");
 }
 
@@ -5626,11 +5604,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page);
  */
 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data)
 {
-	struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+	struct ring_buffer_per_cpu *cpu_buffer;
 	struct buffer_data_page *bpage = data;
 	struct page *page = virt_to_page(bpage);
 	unsigned long flags;
 
+	if (!buffer || !buffer->buffers || !buffer->buffers[cpu])
+		return;
+
+	cpu_buffer = buffer->buffers[cpu];
+
 	/* If the page is still in use someplace else, we can't reuse it */
 	if (page_ref_count(page) > 1)
 		goto out;