linux-kernel - [PATCH 4/4] ucounts: Use atomic_long_sub

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Date:   Mon, 18 Oct 2021 12:57:24 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Alexey Gladkov <legion@...nel.org>
Cc:     Rune Kleveland <rune.kleveland@...omedia.dk>,
        Yu Zhao <yuzhao@...gle.com>,
        Jordan Glover <Golden_Miller83@...tonmail.ch>,
        LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        containers@...ts.linux-foundation.org,
        Hillf Danton <hdanton@...a.com>
Subject: [PATCH 4/4] ucounts: Use atomic_long_sub_return for clarity


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@...gle.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 kernel/ucount.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/ucount.c b/kernel/ucount.c
index 133b6044fda4..4f5613dac227 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -282,7 +282,7 @@ 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;
@@ -295,7 +295,7 @@ 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)
@@ -332,7 +332,7 @@ 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);
 unwind:
 	do_dec_rlimit_put_ucounts(ucounts, iter, type);
-- 
2.20.1