[PATCH 5.15.y 1/4] ucounts: Use atomic_long_sub_return for clarity

[Sasha Levin <sashal@kernel.org>]

From: "Eric W. Biederman" <ebiederm@xmission.com>

[ Upstream commit 32342701b4ba57a6fd77e8aca2f65f68c0fa1da6 ]

Decrement ucounts using atomic_long_sub_return to make it
clear the point is for the ucount to decrease.

Not a big deal but it should make it easier to catch bugs.

Suggested-by: Yu Zhao <yuzhao@google.com>
Link: https://lkml.kernel.org/r/87k0iaqkqj.fsf_-_@disp2133
Tested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Stable-dep-of: b14fcabd34e0 ("ucount: take the rlimit reference before checking the limit")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/ucount.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/ucount.c b/kernel/ucount.c
index cc8ec071d46d3..a751fb6e94e51 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -279,7 +279,7 @@ bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v)
 	struct ucounts *iter;
 	long new = -1; /* Silence compiler warning */
 	for (iter = ucounts; iter; iter = iter->ns->ucounts) {
-		long dec = atomic_long_add_return(-v, &iter->ucount[type]);
+		long dec = atomic_long_sub_return(v, &iter->ucount[type]);
 		WARN_ON_ONCE(dec < 0);
 		if (iter == ucounts)
 			new = dec;
@@ -292,7 +292,7 @@ static void do_dec_rlimit_put_ucounts(struct ucounts *ucounts,
 {
 	struct ucounts *iter, *next;
 	for (iter = ucounts; iter != last; iter = next) {
-		long dec = atomic_long_add_return(-1, &iter->ucount[type]);
+		long dec = atomic_long_sub_return(1, &iter->ucount[type]);
 		WARN_ON_ONCE(dec < 0);
 		next = iter->ns->ucounts;
 		if (dec == 0)
@@ -330,7 +330,7 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum ucount_type type)
 	}
 	return ret;
 dec_unwind:
-	dec = atomic_long_add_return(-1, &iter->ucount[type]);
+	dec = atomic_long_sub_return(1, &iter->ucount[type]);
 	WARN_ON_ONCE(dec < 0);
 	do_dec_rlimit_put_ucounts(ucounts, iter, type);
 	return 0;
-- 
2.53.0