On Tue, 14 May 2024, Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx> wrote:
> This drm printer wrapper can be used to increase the robustness of
> the captured output generated by any other drm_printer to make sure
> we didn't lost any intermediate lines of the output by adding line
> numbers to each output line. Helpful for capturing some crash data.
Interesting. Nothing another level of abstraction can't solve. ;)
Except maybe it'll make adding function names to debug printers harder.
No strong feelings either way about it, I'll let others chime in.
A few comments inline.
BR,
Jani.
>
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_print.c | 9 +++++++++
> include/drm/drm_print.h | 37 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
> index cf2efb44722c..d6fb50d3407a 100644
> --- a/drivers/gpu/drm/drm_print.c
> +++ b/drivers/gpu/drm/drm_print.c
> @@ -214,6 +214,15 @@ void __drm_printfn_err(struct drm_printer *p, struct va_format *vaf)
> }
> EXPORT_SYMBOL(__drm_printfn_err);
>
> +void __drm_printfn_line(struct drm_printer *p, struct va_format *vaf)
> +{
> + unsigned int line = (uintptr_t)(++p->prefix);
Subtle. Might warrant adding a union in struct drm_printer for clarity.
> + struct drm_printer *dp = p->arg;
> +
> + drm_printf(dp, "%u: %pV", line, vaf);
> +}
> +EXPORT_SYMBOL(__drm_printfn_line);
> +
> /**
> * drm_puts - print a const string to a &drm_printer stream
> * @p: the &drm printer
> diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
> index 089950ad8681..58cc73c53853 100644
> --- a/include/drm/drm_print.h
> +++ b/include/drm/drm_print.h
> @@ -186,6 +186,7 @@ void __drm_puts_seq_file(struct drm_printer *p, const char *str);
> void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf);
> void __drm_printfn_dbg(struct drm_printer *p, struct va_format *vaf);
> void __drm_printfn_err(struct drm_printer *p, struct va_format *vaf);
> +void __drm_printfn_line(struct drm_printer *p, struct va_format *vaf);
>
> __printf(2, 3)
> void drm_printf(struct drm_printer *p, const char *f, ...);
> @@ -357,6 +358,42 @@ static inline struct drm_printer drm_err_printer(struct drm_device *drm,
> return p;
> }
>
> +/**
> + * drm_line_printer - construct a &drm_printer that prefixes outputs with line numbers
> + * @dp: the &struct drm_printer which actually generates the output
> + *
> + * This printer can be used to increase the robustness of the captured output
> + * to make sure we didn't lost any intermediate lines of the output. Helpful
> + * while capturing some crash data.
> + *
> + * For example::
> + *
> + * void crash_dump(struct drm_device *drm)
> + * {
> + * struct drm_printer dp = drm_err_printer(drm, "crash");
> + * struct drm_printer lp = drm_line_printer(&dp);
> + *
> + * drm_printf(&lp, "foo");
> + * drm_printf(&lp, "bar");
> + * }
> + *
> + * Above code will print into the dmesg something like::
> + *
> + * [ ] 0000:00:00.0: [drm] *ERROR* crash 1: foo
> + * [ ] 0000:00:00.0: [drm] *ERROR* crash 2: bar
> + *
> + * RETURNS:
> + * The &drm_printer object
> + */
> +static inline struct drm_printer drm_line_printer(struct drm_printer *dp)
Just p is customary for the drm_printer. "dp" gives me too much Display
Port vibes.
> +{
> + struct drm_printer lp = {
> + .printfn = __drm_printfn_line,
> + .arg = dp,
> + };
> + return lp;
> +}
> +
> /*
> * struct device based logging
> *
--
Jani Nikula, Intel
