Merge tag 'v4.4.288' into toradex_vf_4.4

This is the 4.4.288 stable release

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

2 files changed, 32 insertions, 4 deletions

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 8ac3663e0012..c142e100840e 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1581,6 +1581,14 @@ static int blk_trace_remove_queue(struct request_queue *q)
 	if (bt == NULL)
 		return -EINVAL;
 
+	if (bt->trace_state == Blktrace_running) {
+		bt->trace_state = Blktrace_stopped;
+		spin_lock_irq(&running_trace_lock);
+		list_del_init(&bt->running_list);
+		spin_unlock_irq(&running_trace_lock);
+		relay_flush(bt->rchan);
+	}
+
 	put_probe_ref();
 	synchronize_rcu();
 	blk_trace_free(bt);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 1ec760f6bf58..19b30ff90cc4 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3086,10 +3086,30 @@ static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
 	if (unlikely(!head))
 		return true;
 
-	return reader->read == rb_page_commit(reader) &&
-		(commit == reader ||
-		 (commit == head &&
-		  head->read == rb_page_commit(commit)));
+	/* Reader should exhaust content in reader page */
+	if (reader->read != rb_page_commit(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;
+
+	/*
+	 * 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;
 }
 
 /**