vfio-ccw: Add a trace for asynchronous requests

Since the asynchronous requests are typically associated with
error recovery, let's add a simple trace when one of those is
issued to a device.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20191016142040.14132-4-farman@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

drivers/s390/cio/vfio_ccw_fsm.c

@@ -341,6 +341,10 @@ static void fsm_async_request(struct vfio_ccw_private *private,
 		/* should not happen? */
 		cmd_region->ret_code = -EINVAL;
 	}
+
+	trace_vfio_ccw_fsm_async_request(get_schid(private),
+					 cmd_region->command,
+					 cmd_region->ret_code);
 }
 
 /*

drivers/s390/cio/vfio_ccw_trace.c

@@ -9,5 +9,6 @@
 #define CREATE_TRACE_POINTS
 #include "vfio_ccw_trace.h"
 
+EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_fsm_async_request);
 EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_fsm_event);
 EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_io_fctl);

drivers/s390/cio/vfio_ccw_trace.h

@@ -17,6 +17,36 @@
 
 #include <linux/tracepoint.h>
 
+TRACE_EVENT(vfio_ccw_fsm_async_request,
+	TP_PROTO(struct subchannel_id schid,
+		 int command,
+		 int errno),
+	TP_ARGS(schid, command, errno),
+
+	TP_STRUCT__entry(
+		__field(u8, cssid)
+		__field(u8, ssid)
+		__field(u16, sch_no)
+		__field(int, command)
+		__field(int, errno)
+	),
+
+	TP_fast_assign(
+		__entry->cssid = schid.cssid;
+		__entry->ssid = schid.ssid;
+		__entry->sch_no = schid.sch_no;
+		__entry->command = command;
+		__entry->errno = errno;
+	),
+
+	TP_printk("schid=%x.%x.%04x command=0x%x errno=%d",
+		  __entry->cssid,
+		  __entry->ssid,
+		  __entry->sch_no,
+		  __entry->command,
+		  __entry->errno)
+);
+
 TRACE_EVENT(vfio_ccw_fsm_event,
 	TP_PROTO(struct subchannel_id schid, int state, int event),
 	TP_ARGS(schid, state, event),