1 files changed, 28 insertions, 10 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 834b361a4a66..de061dd47313 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -536,6 +536,7 @@ struct trace_buffer {
 	unsigned			flags;
 	int				cpus;
 	atomic_t			record_disabled;
+	atomic_t			resizing;
 	cpumask_var_t			cpumask;
 
 	struct lock_class_key		*reader_lock_key;
@@ -2167,7 +2168,7 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
 
 	/* prevent another thread from changing buffer sizes */
 	mutex_lock(&buffer->mutex);
-
+	atomic_inc(&buffer->resizing);
 
 	if (cpu_id == RING_BUFFER_ALL_CPUS) {
 		/*
@@ -2322,6 +2323,7 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
 		atomic_dec(&buffer->record_disabled);
 	}
 
+	atomic_dec(&buffer->resizing);
 	mutex_unlock(&buffer->mutex);
 	return 0;
 
@@ -2342,6 +2344,7 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
 		}
 	}
  out_err_unlock:
+	atomic_dec(&buffer->resizing);
 	mutex_unlock(&buffer->mutex);
 	return err;
 }
@@ -5242,28 +5245,34 @@ unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu)
 }
 EXPORT_SYMBOL_GPL(ring_buffer_size);
 
+static void rb_clear_buffer_page(struct buffer_page *page)
+{
+	local_set(&page->write, 0);
+	local_set(&page->entries, 0);
+	rb_init_page(page->page);
+	page->read = 0;
+}
+
 static void
 rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 {
+	struct buffer_page *page;
+
 	rb_head_page_deactivate(cpu_buffer);
 
 	cpu_buffer->head_page
 		= list_entry(cpu_buffer->pages, struct buffer_page, list);
-	local_set(&cpu_buffer->head_page->write, 0);
-	local_set(&cpu_buffer->head_page->entries, 0);
-	local_set(&cpu_buffer->head_page->page->commit, 0);
-
-	cpu_buffer->head_page->read = 0;
+	rb_clear_buffer_page(cpu_buffer->head_page);
+	list_for_each_entry(page, cpu_buffer->pages, list) {
+		rb_clear_buffer_page(page);
+	}
 
 	cpu_buffer->tail_page = cpu_buffer->head_page;
 	cpu_buffer->commit_page = cpu_buffer->head_page;
 
 	INIT_LIST_HEAD(&cpu_buffer->reader_page->list);
 	INIT_LIST_HEAD(&cpu_buffer->new_pages);
-	local_set(&cpu_buffer->reader_page->write, 0);
-	local_set(&cpu_buffer->reader_page->entries, 0);
-	local_set(&cpu_buffer->reader_page->page->commit, 0);
-	cpu_buffer->reader_page->read = 0;
+	rb_clear_buffer_page(cpu_buffer->reader_page);
 
 	local_set(&cpu_buffer->entries_bytes, 0);
 	local_set(&cpu_buffer->overrun, 0);
@@ -5535,6 +5544,15 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 	if (local_read(&cpu_buffer_b->committing))
 		goto out_dec;
 
+	/*
+	 * When resize is in progress, we cannot swap it because
+	 * it will mess the state of the cpu buffer.
+	 */
+	if (atomic_read(&buffer_a->resizing))
+		goto out_dec;
+	if (atomic_read(&buffer_b->resizing))
+		goto out_dec;
+
 	buffer_a->buffers[cpu] = cpu_buffer_b;
 	buffer_b->buffers[cpu] = cpu_buffer_a;