--- zzzz-none-000/linux-4.4.60/include/sound/rawmidi.h	2017-04-08 07:53:53.000000000 +0000
+++ scorpion-1750e-727/linux-4.4.60/include/sound/rawmidi.h	2021-02-04 17:41:59.000000000 +0000
@@ -78,6 +78,7 @@
 	size_t xruns;		/* over/underruns counter */
 	/* misc */
 	spinlock_t lock;
+	struct mutex realloc_mutex;
 	wait_queue_head_t sleep;
 	/* event handler (new bytes, input only) */
 	void (*event)(struct snd_rawmidi_substream *substream);