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ns: add asserts for active refcount underflow

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Add a few more assert to detect active reference count underflows.

Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-6-ae8a4ad5a3b3@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-11-09 22:11:27 +01:00
parent f8d5a8970d
commit 57b39aabb9
2 changed files with 14 additions and 5 deletions
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1
include/linux/ns_common.h
View File

@@ -294,7 +294,6 @@ void __ns_ref_active_put(struct ns_common *ns);
static __always_inline struct ns_common *__must_check ns_get_unless_inactive(struct ns_common *ns)
{
VFS_WARN_ON_ONCE(__ns_ref_active_read(ns) && !__ns_ref_read(ns));
if (!__ns_ref_active_read(ns)) {
VFS_WARN_ON_ONCE(is_ns_init_id(ns));
return NULL;

18
kernel/nscommon.c
View File

@@ -170,8 +170,10 @@ void __ns_ref_active_put(struct ns_common *ns)
if (is_ns_init_id(ns))
return;
if (!atomic_dec_and_test(&ns->__ns_ref_active))
if (!atomic_dec_and_test(&ns->__ns_ref_active)) {
VFS_WARN_ON_ONCE(__ns_ref_active_read(ns) < 0);
return;
}
VFS_WARN_ON_ONCE(is_ns_init_id(ns));
VFS_WARN_ON_ONCE(!__ns_ref_read(ns));
@@ -181,8 +183,10 @@ void __ns_ref_active_put(struct ns_common *ns)
if (!ns)
return;
VFS_WARN_ON_ONCE(is_ns_init_id(ns));
if (!atomic_dec_and_test(&ns->__ns_ref_active))
if (!atomic_dec_and_test(&ns->__ns_ref_active)) {
VFS_WARN_ON_ONCE(__ns_ref_active_read(ns) < 0);
return;
}
}
}
@@ -280,12 +284,16 @@ void __ns_ref_active_put(struct ns_common *ns)
*/
void __ns_ref_active_get(struct ns_common *ns)
{
int prev;
/* Initial namespaces are always active. */
if (is_ns_init_id(ns))
return;
/* If we didn't resurrect the namespace we're done. */
if (atomic_fetch_add(1, &ns->__ns_ref_active))
prev = atomic_fetch_add(1, &ns->__ns_ref_active);
VFS_WARN_ON_ONCE(prev < 0);
if (likely(prev))
return;
/*
@@ -298,7 +306,9 @@ void __ns_ref_active_get(struct ns_common *ns)
return;
VFS_WARN_ON_ONCE(is_ns_init_id(ns));
if (atomic_fetch_add(1, &ns->__ns_ref_active))
prev = atomic_fetch_add(1, &ns->__ns_ref_active);
VFS_WARN_ON_ONCE(prev < 0);
if (likely(prev))
return;
}
}