drm/print: Introduce drm_line_printer

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.

v2: Extended short int counters to full int (JohnH)

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241003004611.2323493-8-John.C.Harrison@Intel.com

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 0081190201a7f99095c0857c151080a97b46f7fb..08cfea04e22bd2942f27c982107af251a56b607e 100644 (file)
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -235,6 +235,20 @@ 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 d2676831d765dac97196fa1ec34e8282638b6d28..b3906dc043886bf141675c2dc7f867a4a0710051 100644 (file)
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -177,6 +177,10 @@ struct drm_printer {
        void *arg;
        const void *origin;
        const char *prefix;
+       struct {
+               unsigned int series;
+               unsigned int counter;
+       } line;
        enum drm_debug_category category;
 };
 
@@ -187,6 +191,7 @@ 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, ...);
@@ -411,6 +416,65 @@ 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 int 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 int series)
+{
+       struct drm_printer lp = {
+               .printfn = __drm_printfn_line,
+               .arg = p,
+               .prefix = prefix,
+               .line = { .series = series, },
+       };
+       return lp;
+}
+
 /*
  * struct device based logging
  *