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

Cornelia Huck
2018-05-23T10:25:55Z

On Wed, 23 May 2018 04:56:45 +0200
Dong Jia Shi <bjsdjshi@linux.ibm.com> wrote:

Still s/traceponits/tracepoints/ (can fix up when applying).

> 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);
> }
>
> /*

This approach looks reasonable to me. We can still improve this later,
should we want to.