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From:   Muchun Song <songmuchun@bytedance.com>
To:     corbet@lwn.net, mike.kravetz@oracle.com, akpm@linux-foundation.org,
        mcgrof@kernel.org, keescook@chromium.org, yzaikin@google.com
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, duanxiongchun@bytedance.com,
        Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH 2/3] sysctl: allow to set extra1 to SYSCTL_ONE
Date:   Mon, 28 Feb 2022 15:10:21 +0800
Message-Id: <20220228071022.26143-3-songmuchun@bytedance.com>
In-Reply-To: <20220228071022.26143-1-songmuchun@bytedance.com>
References: <20220228071022.26143-1-songmuchun@bytedance.com>
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Some sysctls only allow to be enabled and cannot be set back to be
disabled. But proc_do_static_key() does not consider this situation,
which set ->extra1 to SYSCTL_ZERO unconditionally. This patch add
the ability to set ->extra1 to SYSCTL_ONE, which will be used in
the next patch.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 kernel/sysctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 64065abf361e..ab3e9c937268 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1631,7 +1631,7 @@ int proc_do_static_key(struct ctl_table *table, int write,
 		.data   = &val,
 		.maxlen = sizeof(val),
 		.mode   = table->mode,
-		.extra1 = SYSCTL_ZERO,
+		.extra1 = table->extra1 == SYSCTL_ONE ? SYSCTL_ONE : SYSCTL_ZERO,
 		.extra2 = SYSCTL_ONE,
 	};
 
-- 
2.11.0