* [PATCH v5 18/18] dyndbg: change __dynamic_func_call_cls* macros into expressions
From: Jim Cromie @ 2026-07-02 16:41 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Jim Cromie, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu, Daniel Gomez, Sami Tolvanen, Aaron Tomlin
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Louis Chauvet
In-Reply-To: <20260702-dd-maint-2-v5-0-24f22b052bf2@gmail.com>
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");
Additionally, change the dynamic_hex_dump() fallback macro (used when
CONFIG_DYNAMIC_DEBUG is disabled) from a do-while-0 statement into a
statement expression returning 0. This ensures that the fallback form
of dynamic_hex_dump() behaves consistently with its enabled form, and
makes it safe for use in conditional expression contexts.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v5: also convert dynamic_hex_dump() stub
v2:
fix statement-expressions to return 0 (not void) like their respective fallbacks
1. Add 0; to __dynamic_func_call_cls
2. Add 0; to __dynamic_func_call_cls_no_desc
3. Convert the disabled fallback of dynamic_hex_dump from do { ... } while(0) to ({ ... 0; })
move RvB after SoB
---
include/linux/dynamic_debug.h | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 355f2cb11733..8822f9a3605f 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -238,24 +238,26 @@ 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__); \
__dynamic_dump_stack(id); \
} \
-} while (0)
+ 0; /* match no_printk return value */ \
+})
#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__); \
__dynamic_dump_stack(id); \
} \
-} while (0)
+ 0; /* match no_printk return value */ \
+})
#define __dynamic_func_call_no_desc(id, fmt, func, ...) \
__dynamic_func_call_cls_no_desc(id, _DPRINTK_CLASS_DFLT, \
fmt, func, ##__VA_ARGS__)
@@ -335,10 +337,12 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
dev_no_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__)
#define dynamic_hex_dump(prefix_str, prefix_type, rowsize, \
groupsize, buf, len, ascii) \
- do { if (0) \
+({ \
+ if (0) \
print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, \
- rowsize, groupsize, buf, len, ascii); \
- } while (0)
+ rowsize, groupsize, buf, len, ascii); \
+ 0; \
+})
#endif /* CONFIG_DYNAMIC_DEBUG || (CONFIG_DYNAMIC_DEBUG_CORE && DYNAMIC_DEBUG_MODULE) */
--
2.54.0
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