[PATCH v3 2/4] vfio-ccw: Trace the FSM jumptable

Eric Farman
2019-10-16T14:20:56Z

It would be nice if we could track the sequence of events within
vfio-ccw, based on the state of the device/FSM and our calling
sequence within it. So let's add a simple trace here so we can
watch the states change as things go, and allow it to be folded
into the rest of the other cio traces.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
drivers/s390/cio/vfio_ccw_private.h | 1 +
drivers/s390/cio/vfio_ccw_trace.c | 1 +
drivers/s390/cio/vfio_ccw_trace.h | 26 ++++++++++++++++++++++++++
3 files changed, 28 insertions(+)

diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index bbe9babf767b..9b9bb4982972 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -135,6 +135,7 @@ extern fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS];
static inline void vfio_ccw_fsm_event(struct vfio_ccw_private *private,
int event)
{
+ trace_vfio_ccw_fsm_event(private->sch->schid, private->state, event);
vfio_ccw_jumptable[private->state][event](private, event);
}

diff --git a/drivers/s390/cio/vfio_ccw_trace.c b/drivers/s390/cio/vfio_ccw_trace.c
index d5cc943c6864..b37bc68e7f18 100644
--- a/drivers/s390/cio/vfio_ccw_trace.c
+++ b/drivers/s390/cio/vfio_ccw_trace.c
@@ -9,4 +9,5 @@
#define CREATE_TRACE_POINTS
#include "vfio_ccw_trace.h"

+EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_fsm_event);
EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_io_fctl);
diff --git a/drivers/s390/cio/vfio_ccw_trace.h b/drivers/s390/cio/vfio_ccw_trace.h
index 2a2937a40124..5005d57901b4 100644
--- a/drivers/s390/cio/vfio_ccw_trace.h
+++ b/drivers/s390/cio/vfio_ccw_trace.h
@@ -17,6 +17,32 @@

#include <linux/tracepoint.h>

+TRACE_EVENT(vfio_ccw_fsm_event,
+ TP_PROTO(struct subchannel_id schid, int state, int event),
+ TP_ARGS(schid, state, event),
+
+ TP_STRUCT__entry(
+ __field(u8, cssid)
+ __field(u8, ssid)
+ __field(u16, schno)
+ __field(int, state)
+ __field(int, event)
+ ),
+
+ TP_fast_assign(
+ __entry->cssid = schid.cssid;
+ __entry->ssid = schid.ssid;
+ __entry->schno = schid.sch_no;
+ __entry->state = state;
+ __entry->event = event;
+ ),
+
+ TP_printk("schid=%x.%x.%04x state=%d event=%d",
+ __entry->cssid, __entry->ssid, __entry->schno,
+ __entry->state,
+ __entry->event)
+);
+
TRACE_EVENT(vfio_ccw_io_fctl,
TP_PROTO(int fctl, struct subchannel_id schid, int errno, char *errstr),
TP_ARGS(fctl, schid, errno, errstr),
--
2.17.1