linux-kernel - [PATCH v4 18/58] dyndbg: change __dynamic_func_call

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Message-ID: <20250803035816.603405-19-jim.cromie@gmail.com>
Date: Sat,  2 Aug 2025 21:57:36 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: linux-kernel@...r.kernel.org,
	jbaron@...mai.com,
	gregkh@...uxfoundation.org,
	ukaszb@...omium.org,
	louis.chauvet@...tlin.com
Cc: dri-devel@...ts.freedesktop.org,
	amd-gfx@...ts.freedesktop.org,
	intel-gvt-dev@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org,
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Subject: [PATCH v4 18/58] 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, and is not an expression.

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

Fix for this usage by changing __dynamic_func_call_cls{,_no_desc}
macros into expressions, by replacing the do-while-0s with a ({ })
wrapper.  In the common usage, the trailing ';' converts the
expression into a statement.

   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 769f02456c8e0..1785ef5b93b15 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -217,20 +217,20 @@ 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__)
-- 
2.50.1