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ns: make all reference counts on initial namespace a nop

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They are always active so no need to needlessly cacheline ping-pong.

Link: https://patch.msgid.link/20251110-work-namespace-nstree-fixes-v1-12-e8a9264e0fb9@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-11-10 16:08:24 +01:00
parent 3826d5dd06
commit 657aeb436d
1 changed files with 22 additions and 3 deletions
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25
include/linux/ns_common.h
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@@ -62,6 +62,8 @@ static __always_inline __must_check int __ns_ref_active_read(const struct ns_com
static __always_inline __must_check bool __ns_ref_put(struct ns_common *ns)
{
if (is_ns_init_id(ns))
return false;
if (refcount_dec_and_test(&ns->__ns_ref)) {
VFS_WARN_ON_ONCE(__ns_ref_active_read(ns));
return true;
@@ -71,6 +73,8 @@ 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))
return true;
if (refcount_inc_not_zero(&ns->__ns_ref))
return true;
VFS_WARN_ON_ONCE(__ns_ref_active_read(ns));
@@ -82,12 +86,27 @@ 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))
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))
return false;
return refcount_dec_and_lock(&ns->__ns_ref, ns_lock);
}
#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_inc(__ns) __ns_ref_inc(to_ns_common((__ns)))
#define ns_ref_get(__ns) __ns_ref_get(to_ns_common((__ns)))
#define ns_ref_put(__ns) __ns_ref_put(to_ns_common((__ns)))
#define ns_ref_put_and_lock(__ns, __lock) \
refcount_dec_and_lock(&to_ns_common((__ns))->__ns_ref, (__lock))
#define ns_ref_put_and_lock(__ns, __ns_lock) \
__ns_ref_dec_and_lock(to_ns_common((__ns)), __ns_lock)
#define ns_ref_active_read(__ns) \
((__ns) ? __ns_ref_active_read(to_ns_common(__ns)) : 0)