linux-kernel - [PATCH v9 26/52] dyndbg: change __dynamic_func_call

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Date: Tue,  2 Jul 2024 15:57:16 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: daniel.vetter@...ll.ch,
	tvrtko.ursulin@...ux.intel.com,
	jani.nikula@...el.com,
	ville.syrjala@...ux.intel.com,
	jbaron@...mai.com,
	gregkh@...uxfoundation.org,
	ukaszb@...omium.org
Cc: linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	amd-gfx@...ts.freedesktop.org,
	intel-gvt-dev@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org,
	linux@...musvillemoes.dk,
	joe@...ches.com,
	mcgrof@...nel.org,
	Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v9 26/52] dyndbg: change __dynamic_func_call_cls* macros into expressions

The Xe driver's XE_IOCTL_DBG macro calls drm_dbg() from inside an if
(expression).  This breaks when CONFIG_DRM_USE_DYNAMIC_DEBUG=y because
the invoked macro has a do-while-0 wrapper.

   if (cond && (drm_dbg("expr-form"),1)) {
      ... do some more stuff
   }

Fix it by changing __dynamic_func_call_cls{,_no_desc} macros into
expressions, by replacing the do-while-0s with a ({ }) wrapper.

In C, all legal expressions are also legal statements, as converted by
the trailing semi-colon in a statement-style macro invocation:

   drm_dbg("statement form");

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 include/linux/dynamic_debug.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 19f959f9a6b4..121a66b0ca25 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -287,20 +287,20 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
  * (|_cls):	adds in _DPRINT_CLASS_DFLT as needed
  * (|_no_desc):	former gets callsite descriptor as 1st arg (for prdbgs)
  */
-#define __dynamic_func_call_cls(id, cls, fmt, func, ...) do {	\
+#define __dynamic_func_call_cls(id, cls, fmt, func, ...) ({	\
 	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt);	\
 	if (DYNAMIC_DEBUG_BRANCH(id))				\
 		func(&id, ##__VA_ARGS__);			\
-} while (0)
+})
 #define __dynamic_func_call(id, fmt, func, ...)				\
 	__dynamic_func_call_cls(id, _DPRINTK_CLASS_DFLT, fmt,		\
 				func, ##__VA_ARGS__)
 
-#define __dynamic_func_call_cls_no_desc(id, cls, fmt, func, ...) do {	\
+#define __dynamic_func_call_cls_no_desc(id, cls, fmt, func, ...) ({	\
 	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt);		\
 	if (DYNAMIC_DEBUG_BRANCH(id))					\
 		func(__VA_ARGS__);					\
-} while (0)
+})
 #define __dynamic_func_call_no_desc(id, fmt, func, ...)			\
 	__dynamic_func_call_cls_no_desc(id, _DPRINTK_CLASS_DFLT,	\
 					fmt, func, ##__VA_ARGS__)
-- 
2.45.2