Re: [PATCH v4 1/2] media: usb: pwc: Introduce TRACE_EVENTs for pwc_isoc_handler()

[Matwey V. Kornilov]

ÑÑ, 9 ÐÐÐ. 2018 Ð. Ð 21:26, Steven Rostedt <rostedt@xxxxxxxxxxx>:
>
> On Thu,  9 Aug 2018 21:11:02 +0300
> "Matwey V. Kornilov" <matwey@xxxxxxxxxx> wrote:
>
> > Signed-off-by: Matwey V. Kornilov <matwey@xxxxxxxxxx>
> > ---
> >  drivers/media/usb/pwc/pwc-if.c |  7 +++++
> >  include/trace/events/pwc.h     | 65 ++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 72 insertions(+)
> >  create mode 100644 include/trace/events/pwc.h
> >
> > diff --git a/drivers/media/usb/pwc/pwc-if.c b/drivers/media/usb/pwc/pwc-if.c
> > index 54b036d39c5b..72d2897a4b9f 100644
> > --- a/drivers/media/usb/pwc/pwc-if.c
> > +++ b/drivers/media/usb/pwc/pwc-if.c
> > @@ -76,6 +76,9 @@
> >  #include "pwc-dec23.h"
> >  #include "pwc-dec1.h"
> >
> > +#define CREATE_TRACE_POINTS
> > +#include <trace/events/pwc.h>
> > +
> >  /* Function prototypes and driver templates */
> >
> >  /* hotplug device table support */
> > @@ -260,6 +263,8 @@ static void pwc_isoc_handler(struct urb *urb)
> >       int i, fst, flen;
> >       unsigned char *iso_buf = NULL;
> >
> > +     trace_pwc_handler_enter(urb, pdev);
> > +
> >       if (urb->status == -ENOENT || urb->status == -ECONNRESET ||
> >           urb->status == -ESHUTDOWN) {
> >               PWC_DEBUG_OPEN("URB (%p) unlinked %ssynchronously.\n",
> > @@ -348,6 +353,8 @@ static void pwc_isoc_handler(struct urb *urb)
> >       }
> >
> >  handler_end:
> > +     trace_pwc_handler_exit(urb, pdev);
> > +
> >       i = usb_submit_urb(urb, GFP_ATOMIC);
> >       if (i != 0)
> >               PWC_ERROR("Error (%d) re-submitting urb in pwc_isoc_handler.\n", i);
> > diff --git a/include/trace/events/pwc.h b/include/trace/events/pwc.h
> > new file mode 100644
> > index 000000000000..84807fea2217
> > --- /dev/null
> > +++ b/include/trace/events/pwc.h
> > @@ -0,0 +1,65 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#if !defined(_TRACE_PWC_H) || defined(TRACE_HEADER_MULTI_READ)
> > +#define _TRACE_PWC_H
> > +
> > +#include <linux/usb.h>
> > +#include <linux/tracepoint.h>
> > +
> > +#undef TRACE_SYSTEM
> > +#define TRACE_SYSTEM pwc
> > +
> > +TRACE_EVENT(pwc_handler_enter,
> > +     TP_PROTO(struct urb *urb, struct pwc_device *pdev),
> > +     TP_ARGS(urb, pdev),
> > +     TP_STRUCT__entry(
> > +             __field(struct urb*, urb)
> > +             __field(int, urb__status)
> > +             __field(u32, urb__actual_length)
> > +             __string(name, pdev->v4l2_dev.name)
> > +             __field(struct pwc_frame_buf*, fbuf)
> > +             __field(int, fbuf__filled)
>
> I should have mentioned this before. The above is a structure, and the
> fields of that structure are created in the same order as this list.
> It's best to try to make sure there's no "holes". I would recommend:
>
>                 __field(struct urb*, urb)
>                 __field(struct pwc_frame_buf*, fbuf)
>                 __field(int, urb__status)
>                 __field(u32, urb__actual_length)
>                 __field(int, fbuf__filled)
>                 __string(name, pdev->v4l2_dev.name)
>
> Best to have names at the end, as in the future I may be able to
> optimize dynamic arrays (like strings) better, if there's only one and
> its at the end of the structure.

I see, thank you!

>
> > +     ),
> > +     TP_fast_assign(
> > +             __entry->urb = urb;
> > +             __entry->urb__status = urb->status;
> > +             __entry->urb__actual_length = urb->actual_length;
> > +             __assign_str(name, pdev->v4l2_dev.name);
> > +             __entry->fbuf = pdev->fill_buf;
> > +             __entry->fbuf__filled = (pdev->fill_buf
> > +                                      ? pdev->fill_buf->filled : 0);
> > +     ),
> > +     TP_printk("dev=%s (fbuf=%p filled=%d) urb=%p (status=%d actual_length=%u)",
> > +             __get_str(name),
> > +             __entry->fbuf,
> > +             __entry->fbuf__filled,
> > +             __entry->urb,
> > +             __entry->urb__status,
> > +             __entry->urb__actual_length)
> > +);
> > +
> > +TRACE_EVENT(pwc_handler_exit,
> > +     TP_PROTO(struct urb *urb, struct pwc_device *pdev),
> > +     TP_ARGS(urb, pdev),
> > +     TP_STRUCT__entry(
> > +             __field(struct urb*, urb)
> > +             __string(name, pdev->v4l2_dev.name)
> > +             __field(struct pwc_frame_buf*, fbuf)
> > +             __field(int, fbuf__filled)
>
> This I would just move name to the end.
>
> Thanks!
>
> -- Steve
>
> > +     ),
> > +     TP_fast_assign(
> > +             __entry->urb = urb;
> > +             __assign_str(name, pdev->v4l2_dev.name);
> > +             __entry->fbuf = pdev->fill_buf;
> > +             __entry->fbuf__filled = pdev->fill_buf->filled;
> > +     ),
> > +     TP_printk(" dev=%s (fbuf=%p filled=%d) urb=%p",
> > +             __get_str(name),
> > +             __entry->fbuf,
> > +             __entry->fbuf__filled,
> > +             __entry->urb)
> > +);
> > +
> > +#endif /* _TRACE_PWC_H */
> > +
> > +/* This part must be outside protection */
> > +#include <trace/define_trace.h>
>


-- 
With best regards,
Matwey V. Kornilov.
Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia
119234, Moscow, Universitetsky pr-k 13, +7 (495) 9392382