__drm_debug() and __drm_dev_dbg() currently printk to syslog. These 2 underlay the vast bulk of DRM.debug api calls; they are a significant source of debugging info, and could add useful context to debug traces.
Wire them to emit 2 new trace_*() events: drm_prdbg and drm_devdbg.
These events keep the args of those 2 callers: - int/enum category, va_format *vaf - struct device *dev, int/enum category, va_format *vaf
ISTM best to reflect args thru w/o altering; it is simple, least surprising, and preserves info for possible filtering/selecting events.
NOTES:
trace_*() additions are strictly redundant with printks to syslog, not properly placed to reduce overall work.
Reuses trim-trailing-newline trick on vnsprintf
TLDR: The event called by __drm_dev_dbg() depends upon !!dev; theres little value to storing a null in the trace. Yes, one could know that devdbg was called with a null, but is that worthwhile ? And if you really needed to know the call (not available from control-file format) the file:line gets you there.
Signed-off-by: Jim Cromie jim.cromie@gmail.com --- drivers/gpu/drm/drm_print.c | 13 +++++-- include/trace/events/drm.h | 68 +++++++++++++++++++++++++++++++++++++ 2 files changed, 78 insertions(+), 3 deletions(-) create mode 100644 include/trace/events/drm.h
diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index f783d4963d4b..cfcb89ffd89d 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -36,6 +36,9 @@ #include <drm/drm_drv.h> #include <drm/drm_print.h>
+#define CREATE_TRACE_POINTS +#include <trace/events/drm.h> + /* * __drm_debug: Enable debug output. * Bitmask of DRM_UT_x. See include/drm/drm_print.h for details. @@ -269,13 +272,15 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category, vaf.fmt = format; vaf.va = &args;
- if (dev) + if (dev) { dev_printk(KERN_DEBUG, dev, "[" DRM_NAME ":%ps] %pV", __builtin_return_address(0), &vaf); - else + trace_drm_devdbg(dev, category, &vaf); + } else { printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", __builtin_return_address(0), &vaf); - + trace_drm_debug(category, &vaf); + } va_end(args); } EXPORT_SYMBOL(drm_dev_dbg); @@ -295,6 +300,8 @@ void __drm_dbg(enum drm_debug_category category, const char *format, ...) printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", __builtin_return_address(0), &vaf);
+ trace_drm_debug(category, &vaf); + va_end(args); } EXPORT_SYMBOL(__drm_dbg); diff --git a/include/trace/events/drm.h b/include/trace/events/drm.h new file mode 100644 index 000000000000..944aedaf6aa6 --- /dev/null +++ b/include/trace/events/drm.h @@ -0,0 +1,68 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM drm + +#if !defined(_TRACE_DRM_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_DRM_H + +#include <linux/tracepoint.h> + +/* drm_debug() was called, pass its args */ +TRACE_EVENT(drm_debug, + TP_PROTO(int drm_debug_category, struct va_format *vaf), + + TP_ARGS(drm_debug_category, vaf), + + TP_STRUCT__entry( + __field(int, drm_debug_category) + __dynamic_array(char, msg, 256) + ), + + TP_fast_assign( + int len; + + __entry->drm_debug_category = drm_debug_category; + vsnprintf(__get_str(msg), 256, vaf->fmt, *vaf->va); + + len = strlen(__get_str(msg)); + if ((len > 0) && (__get_str(msg)[len-1] == '\n')) + len -= 1; + __get_str(msg)[len] = 0; + ), + + TP_printk("%s", __get_str(msg)) +); + +/* drm_devdbg() was called, pass its args, preserving order */ +TRACE_EVENT(drm_devdbg, + TP_PROTO(const struct device *dev, int drm_debug_category, struct va_format *vaf), + + TP_ARGS(dev, drm_debug_category, vaf), + + TP_STRUCT__entry( + __field(const struct device*, dev) + __field(int, drm_debug_category) + __dynamic_array(char, msg, 256) + ), + + TP_fast_assign( + int len; + + __entry->drm_debug_category = drm_debug_category; + __entry->dev = dev; + vsnprintf(__get_str(msg), 256, vaf->fmt, *vaf->va); + + len = strlen(__get_str(msg)); + if ((len > 0) && (__get_str(msg)[len-1] == '\n')) + len -= 1; + __get_str(msg)[len] = 0; + ), + + TP_printk("cat:%d, %s %s", __entry->drm_debug_category, + dev_name(__entry->dev), __get_str(msg)) +); + +#endif /* _TRACE_DRM_H */ + +/* This part must be outside protection */ +#include <trace/define_trace.h>