On Tue, 28 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.
>
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
> Cc: John Harrison <John.C.Harrison@xxxxxxxxx>
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> v2: don't abuse prefix, use union instead (Jani)
> don't use 'dp' as name, prefer 'p' (Jani)
> add support for unique series identifier (John)
> ---
> drivers/gpu/drm/drm_print.c | 14 ++++++++
> include/drm/drm_print.h | 68 ++++++++++++++++++++++++++++++++++++-
> 2 files changed, 81 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
> index cf2efb44722c..be9cbebff5b3 100644
> --- a/drivers/gpu/drm/drm_print.c
> +++ b/drivers/gpu/drm/drm_print.c
> @@ -214,6 +214,20 @@ 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 counter = ++p->line.counter;
> + const char *prefix = p->prefix ?: "";
> + const char *pad = p->prefix ? " " : "";
> +
> + if (p->line.series)
> + drm_printf(p->arg, "%s%s%u.%u: %pV",
> + prefix, pad, p->line.series, counter, vaf);
> + else
> + drm_printf(p->arg, "%s%s%u: %pV", prefix, pad, counter, 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..f4d9b98d7909 100644
> --- a/include/drm/drm_print.h
> +++ b/include/drm/drm_print.h
> @@ -176,7 +176,13 @@ struct drm_printer {
> void (*puts)(struct drm_printer *p, const char *str);
> void *arg;
> const char *prefix;
> - enum drm_debug_category category;
> + union {
> + enum drm_debug_category category;
> + struct {
> + unsigned short series;
> + unsigned short counter;
> + } line;
> + };
> };
>
> void __drm_printfn_coredump(struct drm_printer *p, struct va_format *vaf);
> @@ -186,6 +192,7 @@ 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 +364,65 @@ 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
> + * @p: the &struct drm_printer which actually generates the output
> + * @prefix: optional output prefix, or NULL for no prefix
> + * @series: optional unique series identifier, or 0 to omit identifier in 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.
> + *
> + * Example 1::
> + *
> + * void crash_dump(struct drm_device *drm)
> + * {
> + * static unsigned short id;
> + * struct drm_printer p = drm_err_printer(drm, "crash");
> + * struct drm_printer lp = drm_line_printer(&p, "dump", ++id);
> + *
> + * drm_printf(&lp, "foo");
> + * drm_printf(&lp, "bar");
> + * }
> + *
> + * Above code will print into the dmesg something like::
> + *
> + * [ ] 0000:00:00.0: [drm] *ERROR* crash dump 1.1: foo
> + * [ ] 0000:00:00.0: [drm] *ERROR* crash dump 1.2: bar
> + *
> + * Example 2::
> + *
> + * void line_dump(struct device *dev)
> + * {
> + * struct drm_printer p = drm_info_printer(dev);
> + * struct drm_printer lp = drm_line_printer(&p, NULL, 0);
> + *
> + * drm_printf(&lp, "foo");
> + * drm_printf(&lp, "bar");
> + * }
> + *
> + * Above code will print::
> + *
> + * [ ] 0000:00:00.0: [drm] 1: foo
> + * [ ] 0000:00:00.0: [drm] 2: bar
> + *
> + * RETURNS:
> + * The &drm_printer object
> + */
> +static inline struct drm_printer drm_line_printer(struct drm_printer *p,
> + const char *prefix,
> + unsigned short series)
> +{
> + struct drm_printer lp = {
> + .printfn = __drm_printfn_line,
> + .arg = p,
> + .prefix = prefix,
> + .line = { .series = series, },
> + };
> + return lp;
> +}
> +
> /*
> * struct device based logging
> *
--
Jani Nikula, Intel
