[PATCH 5/6] mm: kmemleak: Wrap section comparison in kmemleak_init with COMPARE_SECTIONS

Nathan Chancellor
2020-02-19T04:54:37Z

Clang warns:

../mm/kmemleak.c:1950:28: warning: array comparison always evaluates to
a constant [-Wtautological-compare]
if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
^
../mm/kmemleak.c:1950:60: warning: array comparison always evaluates to
a constant [-Wtautological-compare]
if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
^
2 warnings generated.

These are not true arrays, they are linker defined symbols, which are
just addresses so there is not a real issue here. Use the
COMPARE_SECTIONS macro to silence this warning by casting the linker
defined symbols to unsigned long, which keeps the logic the same.

Link: https://github.com/ClangBuiltLinux/linux/issues/765
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
mm/kmemleak.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index aa6832432d6a..e27655526ba7 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1952,7 +1952,8 @@ void __init kmemleak_init(void)
create_object((unsigned long)__bss_start, __bss_stop - __bss_start,
KMEMLEAK_GREY, GFP_ATOMIC);
/* only register .data..ro_after_init if not within .data */
- if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
+ if (COMPARE_SECTIONS(__start_ro_after_init, <, _sdata) ||
+ COMPARE_SECTIONS(__end_ro_after_init, >, _edata))
create_object((unsigned long)__start_ro_after_init,
__end_ro_after_init - __start_ro_after_init,
KMEMLEAK_GREY, GFP_ATOMIC);
--
2.25.1