[PATCH v4 4/4] vfio: ccw: add traceponits for interesting error paths

Dong Jia Shi
2018-05-23T02:56:45Z

From: Halil Pasic <pasic@linux.ibm.com>

Add some tracepoints so we can inspect what is not working as is should.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.ibm.com>
---
drivers/s390/cio/Makefile | 1 +
drivers/s390/cio/vfio_ccw_fsm.c | 17 +++++++++++-
drivers/s390/cio/vfio_ccw_trace.h | 54 +++++++++++++++++++++++++++++++++++++++
3 files changed, 71 insertions(+), 1 deletion(-)
create mode 100644 drivers/s390/cio/vfio_ccw_trace.h

diff --git a/drivers/s390/cio/Makefile b/drivers/s390/cio/Makefile
index a070ef0efe65..f230516abb96 100644
--- a/drivers/s390/cio/Makefile
+++ b/drivers/s390/cio/Makefile
@@ -5,6 +5,7 @@

# The following is required for define_trace.h to find ./trace.h
CFLAGS_trace.o := -I$(src)
+CFLAGS_vfio_ccw_fsm.o := -I$(src)

obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o isc.o \
fcx.o itcw.o crw.o ccwreq.o trace.o ioasm.o
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index 3c800642134e..797a82731159 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -13,6 +13,9 @@
#include "ioasm.h"
#include "vfio_ccw_private.h"

+#define CREATE_TRACE_POINTS
+#include "vfio_ccw_trace.h"
+
static int fsm_io_helper(struct vfio_ccw_private *private)
{
struct subchannel *sch;
@@ -110,6 +113,10 @@ static void fsm_disabled_irq(struct vfio_ccw_private *private,
*/
cio_disable_subchannel(sch);
}
+inline struct subchannel_id get_schid(struct vfio_ccw_private *p)
+{
+ return p->sch->schid;
+}

/*
* Deal with the ccw command request from the userspace.
@@ -121,6 +128,7 @@ static void fsm_io_request(struct vfio_ccw_private *private,
union scsw *scsw = &private->scsw;
struct ccw_io_region *io_region = &private->io_region;
struct mdev_device *mdev = private->mdev;
+ char *errstr = "request";

private->state = VFIO_CCW_STATE_BOXED;

@@ -132,15 +140,19 @@ static void fsm_io_request(struct vfio_ccw_private *private,
/* Don't try to build a cp if transport mode is specified. */
if (orb->tm.b) {
io_region->ret_code = -EOPNOTSUPP;
+ errstr = "transport mode";
goto err_out;
}
io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev),
orb);
- if (io_region->ret_code)
+ if (io_region->ret_code) {
+ errstr = "cp init";
goto err_out;
+ }

io_region->ret_code = cp_prefetch(&private->cp);
if (io_region->ret_code) {
+ errstr = "cp prefetch";
cp_free(&private->cp);
goto err_out;
}
@@ -148,6 +160,7 @@ static void fsm_io_request(struct vfio_ccw_private *private,
/* Start channel program and wait for I/O interrupt. */
io_region->ret_code = fsm_io_helper(private);
if (io_region->ret_code) {
+ errstr = "cp fsm_io_helper";
cp_free(&private->cp);
goto err_out;
}
@@ -164,6 +177,8 @@ static void fsm_io_request(struct vfio_ccw_private *private,

err_out:
private->state = VFIO_CCW_STATE_IDLE;
+ trace_vfio_ccw_io_fctl(scsw->cmd.fctl, get_schid(private),
+ io_region->ret_code, errstr);
}

/*
diff --git a/drivers/s390/cio/vfio_ccw_trace.h b/drivers/s390/cio/vfio_ccw_trace.h
new file mode 100644
index 000000000000..b1da53ddec1f
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_trace.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Tracepoints for vfio_ccw driver
+ *
+ * Copyright IBM Corp. 2018
+ *
+ * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ * Halil Pasic <pasic@linux.vnet.ibm.com>
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM vfio_ccw
+
+#if !defined(_VFIO_CCW_TRACE_) || defined(TRACE_HEADER_MULTI_READ)
+#define _VFIO_CCW_TRACE_
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(vfio_ccw_io_fctl,
+ TP_PROTO(int fctl, struct subchannel_id schid, int errno, char *errstr),
+ TP_ARGS(fctl, schid, errno, errstr),
+
+ TP_STRUCT__entry(
+ __field(int, fctl)
+ __field_struct(struct subchannel_id, schid)
+ __field(int, errno)
+ __field(char*, errstr)
+ ),
+
+ TP_fast_assign(
+ __entry->fctl = fctl;
+ __entry->schid = schid;
+ __entry->errno = errno;
+ __entry->errstr = errstr;
+ ),
+
+ TP_printk("schid=%x.%x.%04x fctl=%x errno=%d info=%s",
+ __entry->schid.cssid,
+ __entry->schid.ssid,
+ __entry->schid.sch_no,
+ __entry->fctl,
+ __entry->errno,
+ __entry->errstr)
+);
+
+#endif /* _VFIO_CCW_TRACE_ */
+
+/* This part must be outside protection */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE vfio_ccw_trace
+
+#include <trace/define_trace.h>
--
2.16.3