[PATCH 13/17] ns: add asserts for initial namespace reference counts
From: Christian Brauner <brauner@kernel.org>
Date: 2025-11-10 15:09:49
Also in:
bpf, cgroups, linux-fsdevel, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
They always remain fixed at one. Notice when that assumptions is broken. Signed-off-by: Christian Brauner <brauner@kernel.org> --- include/linux/ns_common.h | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-)
diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h
index 5b8f2f0163d7..dfb6b798ba82 100644
--- a/include/linux/ns_common.h
+++ b/include/linux/ns_common.h@@ -60,10 +60,17 @@ static __always_inline __must_check int __ns_ref_active_read(const struct ns_com return atomic_read(&ns->__ns_ref_active); } +static __always_inline __must_check int __ns_ref_read(const struct ns_common *ns) +{ + return refcount_read(&ns->__ns_ref); +} + static __always_inline __must_check bool __ns_ref_put(struct ns_common *ns) { - if (is_ns_init_id(ns)) + if (is_ns_init_id(ns)) { + VFS_WARN_ON_ONCE(__ns_ref_read(ns) != 1); return false; + } if (refcount_dec_and_test(&ns->__ns_ref)) { VFS_WARN_ON_ONCE(__ns_ref_active_read(ns)); return true;
@@ -73,31 +80,32 @@ static __always_inline __must_check bool __ns_ref_put(struct ns_common *ns) static __always_inline __must_check bool __ns_ref_get(struct ns_common *ns) { - if (is_ns_init_id(ns)) + if (is_ns_init_id(ns)) { + VFS_WARN_ON_ONCE(__ns_ref_read(ns) != 1); return true; + } if (refcount_inc_not_zero(&ns->__ns_ref)) return true; VFS_WARN_ON_ONCE(__ns_ref_active_read(ns)); return false; } -static __always_inline __must_check int __ns_ref_read(const struct ns_common *ns) -{ - return refcount_read(&ns->__ns_ref); -} - static __always_inline void __ns_ref_inc(struct ns_common *ns) { - if (is_ns_init_id(ns)) + if (is_ns_init_id(ns)) { + VFS_WARN_ON_ONCE(__ns_ref_read(ns) != 1); return; + } refcount_inc(&ns->__ns_ref); } static __always_inline __must_check bool __ns_ref_dec_and_lock(struct ns_common *ns, spinlock_t *ns_lock) { - if (is_ns_init_id(ns)) + if (is_ns_init_id(ns)) { + VFS_WARN_ON_ONCE(__ns_ref_read(ns) != 1); return false; + } return refcount_dec_and_lock(&ns->__ns_ref, ns_lock); }
--
2.47.3