On Sun, Oct 13, 2024 at 12:01:24PM +0800, kernel test robot wrote:
912 | scoped_guard(rcu) {drivers/firewire/core-transaction.c:912:2: warning: variable 'handler' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
| ^~~~~~~~~~~~~~~~~
include/linux/cleanup.h:197:2: note: expanded from macro 'scoped_guard'
197 | __scoped_guard(_name, /* empty */, __UNIQUE_ID(label), args)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/cleanup.h:190:3: note: expanded from macro '__scoped_guard'
190 | if (!__guard_ptr(_name)(&scope) && __is_cond_ptr(_name)) { \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:55:28: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:57:30: note: expanded from macro '__trace_if_var'
57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/firewire/core-transaction.c:921:7: note: uninitialized use occurs here
921 | if (!handler)
| ^~~~~~~
include/linux/compiler.h:55:47: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^~~~
include/linux/compiler.h:57:52: note: expanded from macro '__trace_if_var'
57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
| ^~~~
drivers/firewire/core-transaction.c:912:2: note: remove the 'if' if its condition is always false
912 | scoped_guard(rcu) {
| ^
include/linux/cleanup.h:197:2: note: expanded from macro 'scoped_guard'
197 | __scoped_guard(_name, /* empty */, __UNIQUE_ID(label), args)
| ^
include/linux/cleanup.h:190:3: note: expanded from macro '__scoped_guard'
190 | if (!__guard_ptr(_name)(&scope) && __is_cond_ptr(_name)) { \
| ^
include/linux/compiler.h:55:23: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^
drivers/firewire/core-transaction.c:903:36: note: initialize the variable 'handler' to silence this warning
903 | struct fw_address_handler *handler;
| ^
| = NULL
1 warning generated.
So this goes away when we do:
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -323,7 +323,7 @@ static __maybe_unused const bool class_#
*/
#define __scoped_guard(_name, _fail, _label, args...) \
for (CLASS(_name, scope)(args); true; ({ goto _label; })) \
- if (!__guard_ptr(_name)(&scope) && __is_cond_ptr(_name)) { \
+ if (__is_cond_ptr(_name) && !__guard_ptr(_name)(&scope)) { \
_fail; \
_label: \
break; \