drm_print: wrap drm_*_dbg in dyndbg descriptor factory macro

For CONFIG_DRM_USE_DYNAMIC_DEBUG=y, wrap __drm_dbg() & __drm_dev_dbg()
in one of dyndbg's Factory macros: _dynamic_func_call_no_desc().

This adds the callsite descriptor into the code, and an entry for each
into /proc/dynamic_debug/control.

  #> echo class DRM_UT_ATOMIC +p > /proc/dynamic_debug/control

CONFIG_DRM_USE_DYNAMIC_DEBUG=y/n is configurable because of the .data
footprint cost of per-callsite control; 56 bytes/site * ~2k for i915,
~4k callsites for amdgpu.  This is large enough that a kernel builder
might not want it.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220912052852.1123868-5-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 6c2256e..2438e0d 100644 (file)
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -50,6 +50,18 @@ config DRM_DEBUG_MM
 
          If in doubt, say "N".
 
+config DRM_USE_DYNAMIC_DEBUG
+       bool "use dynamic debug to implement drm.debug"
+       default y
+       depends on DRM
+       depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
+       depends on JUMP_LABEL
+       help
+         Use dynamic-debug to avoid drm_debug_enabled() runtime overheads.
+         Due to callsite counts in DRM drivers (~4k in amdgpu) and 56
+         bytes per callsite, the .data costs can be substantial, and
+         are therefore configurable.
+
 config DRM_DEBUG_SELFTEST
        tristate "kselftests for DRM"
        depends on DRM

diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index e7af358..6828197 100644 (file)
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -3,6 +3,8 @@
 # Makefile for the drm device driver.  This driver provides support for the
 # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
 
+CFLAGS-$(CONFIG_DRM_USE_DYNAMIC_DEBUG) += -DDYNAMIC_DEBUG_MODULE
+
 drm-y       := drm_aperture.o drm_auth.o drm_cache.o \
                drm_file.o drm_gem.o drm_ioctl.o \
                drm_drv.o \

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index c429c25..2d2cef7 100644 (file)
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -384,8 +384,14 @@ void __drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
        }                                                               \
 })
 
+#if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
 #define drm_dev_dbg(dev, cat, fmt, ...)                                \
        __drm_dev_dbg(dev, cat, fmt, ##__VA_ARGS__)
+#else
+#define drm_dev_dbg(dev, cat, fmt, ...)                                \
+       _dynamic_func_call_no_desc(fmt, __drm_dev_dbg,                  \
+                                  dev, cat, fmt, ##__VA_ARGS__)
+#endif
 
 /**
  * DRM_DEV_DEBUG() - Debug output for generic drm code
@@ -492,7 +498,13 @@ void ___drm_dbg(enum drm_debug_category category, const char *format, ...);
 __printf(1, 2)
 void __drm_err(const char *format, ...);
 
+#if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
 #define __drm_dbg(fmt, ...)            ___drm_dbg(fmt, ##__VA_ARGS__)
+#else
+#define __drm_dbg(cat, fmt, ...)                                       \
+       _dynamic_func_call_no_desc(fmt, ___drm_dbg,                     \
+                                  cat, fmt, ##__VA_ARGS__)
+#endif
 
 /* Macros to make printk easier */