[PATCH 6.18.y 1/3] ns: add __ns_ref_read()

[Sasha Levin <sashal@kernel.org>]

From: Christian Brauner <brauner@kernel.org>

[ Upstream commit 6b053576edb12c7739ea9c7c9900031361922631 ]

Implement ns_ref_read() the same way as ns_ref_{get,put}().
No point in making that any more special or different from the other
helpers.

Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-9-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: cdd812d0683d ("exit: hold a reference to thread_pid across proc_flush_pid")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/ns_common.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h
index f3c52904343e7..08ff44e631456 100644
--- a/include/linux/ns_common.h
+++ b/include/linux/ns_common.h
@@ -156,7 +156,12 @@ static __always_inline __must_check bool __ns_ref_get(struct ns_common *ns)
 	return refcount_inc_not_zero(&ns->__ns_ref);
 }
 
-#define ns_ref_read(__ns) refcount_read(&to_ns_common((__ns))->__ns_ref)
+static __always_inline __must_check int __ns_ref_read(const struct ns_common *ns)
+{
+	return refcount_read(&ns->__ns_ref);
+}
+
+#define ns_ref_read(__ns) __ns_ref_read(to_ns_common((__ns)))
 #define ns_ref_inc(__ns) refcount_inc(&to_ns_common((__ns))->__ns_ref)
 #define ns_ref_get(__ns) __ns_ref_get(to_ns_common((__ns)))
 #define ns_ref_put(__ns) __ns_ref_put(to_ns_common((__ns)))
-- 
2.53.0