The trace_printk() macro uses a local variable _______STR to detect
whether variadic arguments are present. This name can shadow outer
variables.
Replace the local variable with sizeof applied directly to the
stringified arguments:
if (sizeof __stringify((__VA_ARGS__)) > 3)
This eliminates the shadowing risk entirely without introducing
any additional includes or local variables.
Verified with objdump on samples/trace_printk that all four cases
branch correctly: __trace_bputs, __trace_puts, __trace_bprintk,
and __trace_printk.
Suggested-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Qian-Yu Lin <tiffany019230@gmail.com>
---
include/linux/trace_printk.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/include/linux/trace_printk.h b/include/linux/trace_printk.h
index 2670ec7f4262..3d54f440dccf 100644
--- a/include/linux/trace_printk.h
+++ b/include/linux/trace_printk.h
@@ -86,8 +86,7 @@ do { \
#define trace_printk(fmt, ...) \
do { \
- char _______STR[] = __stringify((__VA_ARGS__)); \
- if (sizeof(_______STR) > 3) \
+ if (sizeof __stringify((__VA_ARGS__)) > 3) \
do_trace_printk(fmt, ##__VA_ARGS__); \
else \
trace_puts(fmt); \
--
2.43.0