1 files changed, 17 insertions, 46 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 60210fb5b211..6d61ff78926b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4682,40 +4682,22 @@ int ring_buffer_write(struct trace_buffer *buffer,
 }
 EXPORT_SYMBOL_GPL(ring_buffer_write);
 
-static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
+/*
+ * The total entries in the ring buffer is the running counter
+ * of entries entered into the ring buffer, minus the sum of
+ * the entries read from the ring buffer and the number of
+ * entries that were overwritten.
+ */
+static inline unsigned long
+rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer)
 {
-	struct buffer_page *reader = cpu_buffer->reader_page;
-	struct buffer_page *head = rb_set_head_page(cpu_buffer);
-	struct buffer_page *commit = cpu_buffer->commit_page;
-
-	/* In case of error, head will be NULL */
-	if (unlikely(!head))
-		return true;
-
-	/* Reader should exhaust content in reader page */
-	if (reader->read != rb_page_size(reader))
-		return false;
-
-	/*
-	 * If writers are committing on the reader page, knowing all
-	 * committed content has been read, the ring buffer is empty.
-	 */
-	if (commit == reader)
-		return true;
-
-	/*
-	 * If writers are committing on a page other than reader page
-	 * and head page, there should always be content to read.
-	 */
-	if (commit != head)
-		return false;
+	return local_read(&cpu_buffer->entries) -
+		(local_read(&cpu_buffer->overrun) + cpu_buffer->read);
+}
 
-	/*
-	 * Writers are committing on the head page, we just need
-	 * to care about there're committed data, and the reader will
-	 * swap reader page with head page when it is to read data.
-	 */
-	return rb_page_commit(commit) == 0;
+static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
+{
+	return !rb_num_of_entries(cpu_buffer);
 }
 
 /**
@@ -4861,19 +4843,6 @@ void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu)
 }
 EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu);
 
-/*
- * The total entries in the ring buffer is the running counter
- * of entries entered into the ring buffer, minus the sum of
- * the entries read from the ring buffer and the number of
- * entries that were overwritten.
- */
-static inline unsigned long
-rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer)
-{
-	return local_read(&cpu_buffer->entries) -
-		(local_read(&cpu_buffer->overrun) + cpu_buffer->read);
-}
-
 /**
  * ring_buffer_oldest_event_ts - get the oldest event timestamp from the buffer
  * @buffer: The ring buffer
@@ -7059,7 +7028,7 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer,
 	}
 
 	while (p < nr_pages) {
-		struct page *page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]);
+		struct page *page;
 		int off = 0;
 
 		if (WARN_ON_ONCE(s >= nr_subbufs)) {
@@ -7067,6 +7036,8 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer,
 			goto out;
 		}
 
+		page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]);
+
 		for (; off < (1 << (subbuf_order)); off++, page++) {
 			if (p >= nr_pages)
 				break;