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Message-Id: <20250917-work-namespace-ns_common-v1-8-1b3bda8ef8f2@kernel.org>
Date: Wed, 17 Sep 2025 12:28:07 +0200
From: Christian Brauner <brauner@...nel.org>
To: linux-fsdevel@...r.kernel.org
Cc: Amir Goldstein <amir73il@...il.com>, Josef Bacik <josef@...icpanda.com>,
Jeff Layton <jlayton@...nel.org>, Mike Yuan <me@...dnzj.com>,
Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>,
Lennart Poettering <mzxreary@...inter.de>,
Daan De Meyer <daan.j.demeyer@...il.com>, Aleksa Sarai <cyphar@...har.com>,
Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
Tejun Heo <tj@...nel.org>, Johannes Weiner <hannes@...xchg.org>,
Michal Koutný <mkoutny@...e.com>,
Jakub Kicinski <kuba@...nel.org>,
Anna-Maria Behnsen <anna-maria@...utronix.de>,
Frederic Weisbecker <frederic@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>, cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
Christian Brauner <brauner@...nel.org>
Subject: [PATCH 8/9] nscommon: simplify initialization
There's a lot of information that namespace implementers don't need to
know about at all. Encapsulate this all in the initialization helper.
Signed-off-by: Christian Brauner <brauner@...nel.org>
---
fs/namespace.c | 5 +++--
include/linux/ns_common.h | 41 +++++++++++++++++++++++++++++++++++++++--
ipc/namespace.c | 2 +-
kernel/cgroup/namespace.c | 2 +-
kernel/nscommon.c | 17 ++++++++---------
kernel/pid_namespace.c | 2 +-
kernel/time/namespace.c | 2 +-
kernel/user_namespace.c | 2 +-
kernel/utsname.c | 2 +-
net/core/net_namespace.c | 2 +-
10 files changed, 57 insertions(+), 20 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 09e4ecd44972..31eb0e8f21eb 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -4105,8 +4105,9 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool a
}
if (anon)
- new_ns->ns.inum = MNT_NS_ANON_INO;
- ret = ns_common_init(&new_ns->ns, &mntns_operations, !anon);
+ ret = ns_common_init_inum(new_ns, &mntns_operations, MNT_NS_ANON_INO);
+ else
+ ret = ns_common_init(new_ns, &mntns_operations);
if (ret) {
kfree(new_ns);
dec_mnt_namespaces(ucounts);
diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h
index 78b17fe80b62..284bba2b7c43 100644
--- a/include/linux/ns_common.h
+++ b/include/linux/ns_common.h
@@ -16,6 +16,15 @@ struct time_namespace;
struct user_namespace;
struct uts_namespace;
+extern struct cgroup_namespace init_cgroup_ns;
+extern struct ipc_namespace init_ipc_ns;
+extern struct mnt_namespace *init_mnt_ns;
+extern struct net init_net;
+extern struct pid_namespace init_pid_ns;
+extern struct time_namespace init_time_ns;
+extern struct user_namespace init_user_ns;
+extern struct uts_namespace init_uts_ns;
+
struct ns_common {
struct dentry *stashed;
const struct proc_ns_operations *ops;
@@ -31,8 +40,7 @@ struct ns_common {
};
};
-int ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops,
- bool alloc_inum);
+int __ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops, int inum);
#define to_ns_common(__ns) \
_Generic((__ns), \
@@ -45,4 +53,33 @@ int ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops,
struct user_namespace *: &(__ns)->ns, \
struct uts_namespace *: &(__ns)->ns)
+#define ns_init_inum(__ns) \
+ _Generic((__ns), \
+ struct cgroup_namespace *: CGROUP_NS_INIT_INO, \
+ struct ipc_namespace *: IPC_NS_INIT_INO, \
+ struct mnt_namespace *: MNT_NS_INIT_INO, \
+ struct net *: NET_NS_INIT_INO, \
+ struct pid_namespace *: PID_NS_INIT_INO, \
+ struct time_namespace *: TIME_NS_INIT_INO, \
+ struct user_namespace *: USER_NS_INIT_INO, \
+ struct uts_namespace *: UTS_NS_INIT_INO)
+
+#define ns_init_ns(__ns) \
+ _Generic((__ns), \
+ struct cgroup_namespace *: &init_cgroup_ns, \
+ struct ipc_namespace *: &init_ipc_ns, \
+ struct mnt_namespace *: init_mnt_ns, \
+ struct net *: &init_net, \
+ struct pid_namespace *: &init_pid_ns, \
+ struct time_namespace *: &init_time_ns, \
+ struct user_namespace *: &init_user_ns, \
+ struct uts_namespace *: &init_uts_ns)
+
+#define ns_common_init(__ns, __ops) \
+ __ns_common_init(&(__ns)->ns, __ops, \
+ (((__ns) == ns_init_ns(__ns)) ? ns_init_inum(__ns) : 0))
+
+#define ns_common_init_inum(__ns, __ops, __inum) \
+ __ns_common_init(&(__ns)->ns, __ops, __inum)
+
#endif
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 89588819956b..0f8bbd18a475 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -62,7 +62,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
if (ns == NULL)
goto fail_dec;
- err = ns_common_init(&ns->ns, &ipcns_operations, true);
+ err = ns_common_init(ns, &ipcns_operations);
if (err)
goto fail_free;
diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c
index 5a327914b565..d928c557e28b 100644
--- a/kernel/cgroup/namespace.c
+++ b/kernel/cgroup/namespace.c
@@ -27,7 +27,7 @@ static struct cgroup_namespace *alloc_cgroup_ns(void)
new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL_ACCOUNT);
if (!new_ns)
return ERR_PTR(-ENOMEM);
- ret = ns_common_init(&new_ns->ns, &cgroupns_operations, true);
+ ret = ns_common_init(new_ns, &cgroupns_operations);
if (ret)
return ERR_PTR(ret);
ns_tree_add(new_ns);
diff --git a/kernel/nscommon.c b/kernel/nscommon.c
index e10fad8afe61..c3a90bb665ad 100644
--- a/kernel/nscommon.c
+++ b/kernel/nscommon.c
@@ -1,21 +1,20 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/ns_common.h>
+#include <linux/proc_ns.h>
-int ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops,
- bool alloc_inum)
+int __ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops, int inum)
{
- if (alloc_inum && !ns->inum) {
- int ret;
- ret = proc_alloc_inum(&ns->inum);
- if (ret)
- return ret;
- }
refcount_set(&ns->count, 1);
ns->stashed = NULL;
ns->ops = ops;
ns->ns_id = 0;
RB_CLEAR_NODE(&ns->ns_tree_node);
INIT_LIST_HEAD(&ns->ns_list_node);
- return 0;
+
+ if (inum) {
+ ns->inum = inum;
+ return 0;
+ }
+ return proc_alloc_inum(&ns->inum);
}
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 9b327420309e..170757c265c2 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -103,7 +103,7 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
if (ns->pid_cachep == NULL)
goto out_free_idr;
- err = ns_common_init(&ns->ns, &pidns_operations, true);
+ err = ns_common_init(ns, &pidns_operations);
if (err)
goto out_free_idr;
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 20b65f90549e..ce8e952104a7 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -97,7 +97,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
if (!ns->vvar_page)
goto fail_free;
- err = ns_common_init(&ns->ns, &timens_operations, true);
+ err = ns_common_init(ns, &timens_operations);
if (err)
goto fail_free_page;
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index cfb0e28f2779..db9f0463219c 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -126,7 +126,7 @@ int create_user_ns(struct cred *new)
ns->parent_could_setfcap = cap_raised(new->cap_effective, CAP_SETFCAP);
- ret = ns_common_init(&ns->ns, &userns_operations, true);
+ ret = ns_common_init(ns, &userns_operations);
if (ret)
goto fail_free;
diff --git a/kernel/utsname.c b/kernel/utsname.c
index a682830742d3..399888be66bd 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -50,7 +50,7 @@ static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
if (!ns)
goto fail_dec;
- err = ns_common_init(&ns->ns, &utsns_operations, true);
+ err = ns_common_init(ns, &utsns_operations);
if (err)
goto fail_free;
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 897f4927df9e..fdb266bbdf93 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -409,7 +409,7 @@ static __net_init int preinit_net(struct net *net, struct user_namespace *user_n
ns_ops = NULL;
#endif
- ret = ns_common_init(&net->ns, ns_ops, true);
+ ret = ns_common_init(net, ns_ops);
if (ret)
return ret;
--
2.47.3
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