mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-12-28 06:44:36 -05:00
Code Issues Packages Projects Releases Wiki Activity

ns: don't increment or decrement initial namespaces

Browse Source 
There's no need to bump the active reference counts of initial
namespaces as they're always active and can simply remain at 1.

Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-2-ae8a4ad5a3b3@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-11-09 22:11:23 +01:00
parent 0355dcae2d
commit 7cd3d20441
2 changed files with 26 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
include/linux/ns_common.h
View File

@@ -141,6 +141,12 @@ static __always_inline bool is_initial_namespace(struct ns_common *ns)
IPC_NS_INIT_INO - MNT_NS_INIT_INO + 1));
}
static __always_inline bool is_ns_init_id(const struct ns_common *ns)
{
VFS_WARN_ON_ONCE(ns->ns_id == 0);
return ns->ns_id <= NS_LAST_INIT_ID;
}
#define to_ns_common(__ns) \
_Generic((__ns), \
struct cgroup_namespace *: &(__ns)->ns, \
@@ -285,14 +291,19 @@ void __ns_ref_active_get_owner(struct ns_common *ns);
static __always_inline void __ns_ref_active_get(struct ns_common *ns)
{
WARN_ON_ONCE(atomic_add_negative(1, &ns->__ns_ref_active));
VFS_WARN_ON_ONCE(is_initial_namespace(ns) && __ns_ref_active_read(ns) <= 0);
/* Initial namespaces are always active. */
if (!is_ns_init_id(ns))
WARN_ON_ONCE(atomic_add_negative(1, &ns->__ns_ref_active));
}
#define ns_ref_active_get(__ns) \
do { if (__ns) __ns_ref_active_get(to_ns_common(__ns)); } while (0)
static __always_inline bool __ns_ref_active_get_not_zero(struct ns_common *ns)
{
/* Initial namespaces are always active. */
if (is_ns_init_id(ns))
return true;
if (atomic_inc_not_zero(&ns->__ns_ref_active)) {
VFS_WARN_ON_ONCE(!__ns_ref_read(ns));
return true;
@@ -307,6 +318,10 @@ void __ns_ref_active_put_owner(struct ns_common *ns);
static __always_inline void __ns_ref_active_put(struct ns_common *ns)
{
/* Initial namespaces are always active. */
if (is_ns_init_id(ns))
return;
if (atomic_dec_and_test(&ns->__ns_ref_active)) {
VFS_WARN_ON_ONCE(is_initial_namespace(ns));
VFS_WARN_ON_ONCE(!__ns_ref_read(ns));
@@ -319,8 +334,10 @@ static __always_inline 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))
if (!__ns_ref_active_read(ns)) {
VFS_WARN_ON_ONCE(is_ns_init_id(ns));
return NULL;
}
if (!__ns_ref_get(ns))
return NULL;
return ns;

6
kernel/nscommon.c
View File

@@ -177,6 +177,7 @@ void __ns_ref_active_put_owner(struct ns_common *ns)
ns = ns_owner(ns);
if (!ns)
return;
VFS_WARN_ON_ONCE(is_ns_init_id(ns));
if (!atomic_dec_and_test(&ns->__ns_ref_active))
return;
}
@@ -276,6 +277,10 @@ void __ns_ref_active_put_owner(struct ns_common *ns)
*/
void __ns_ref_active_resurrect(struct ns_common *ns)
{
/* 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))
return;
@@ -289,6 +294,7 @@ void __ns_ref_active_resurrect(struct ns_common *ns)
if (!ns)
return;
VFS_WARN_ON_ONCE(is_ns_init_id(ns));
if (atomic_fetch_add(1, &ns->__ns_ref_active))
return;
}