[PATCH] kernel/resource: Fix use of ternary condition in release_mem_region_adjustable

From: Nathan Chancellor
Date: Tue Sep 22 2020 - 02:08:18 EST


Clang warns:

kernel/resource.c:1281:53: warning: operator '?:' has lower precedence
than '|'; '|' will be evaluated first
[-Wbitwise-conditional-parentheses]
new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
~~~~~~~~~~~~~~~~~~~~~~~~~ ^
kernel/resource.c:1281:53: note: place parentheses around the '|'
expression to silence this warning
new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
~~~~~~~~~~~~~~~~~~~~~~~~~ ^
kernel/resource.c:1281:53: note: place parentheses around the '?:'
expression to evaluate it first
new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
^
( )
1 warning generated.

Add the parentheses as it was clearly intended for the ternary condition
to be evaluated first.

Fixes: 5fd23bd0d739 ("kernel/resource: make release_mem_region_adjustable() never fail")
Link: https://github.com/ClangBuiltLinux/linux/issues/1159
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
---

Presumably, this will be squashed but I included a fixes tag
nonetheless. Apologies if this has already been noticed and fixed
already, I did not find anything on LKML.

kernel/resource.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index ca2a666e4317..3ae2f56cc79d 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1278,7 +1278,7 @@ void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
* similarly).
*/
retry:
- new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
+ new_res = alloc_resource(GFP_KERNEL | (alloc_nofail ? __GFP_NOFAIL : 0));

p = &parent->child;
write_lock(&resource_lock);

base-commit: 40ee82f47bf297e31d0c47547cd8f24ede52415a
--
2.28.0