Merge patch series "ns: tweak ns common handling"

Christian Brauner <brauner@kernel.org> says:

This contains three minor tweaks for namespace handling:

* Make struct ns_tree private. There's no need for anything to access
  that directly.

* Drop a debug assert that would trigger in conditions that are benign.

* Move the type of the namespace out of struct proc_ns_operations and
  into struct ns_common. This eliminates a pointer dereference and also
  allows assertions to work when the namespace type is disabled and the
  operations field set to NULL.

* patches from https://lore.kernel.org/20250924-work-namespaces-fixes-v1-0-8fb682c8678e@kernel.org:
  ns: drop assert
  ns: move ns type into struct ns_common
  nstree: make struct ns_tree private

Signed-off-by: Christian Brauner <brauner@kernel.org>

3 files changed, 25 insertions, 19 deletions

diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h
index 56492cd9ff8d..f5b68b8abb54 100644
--- a/include/linux/ns_common.h
+++ b/include/linux/ns_common.h
@@ -4,6 +4,7 @@
 
 #include <linux/refcount.h>
 #include <linux/rbtree.h>
+#include <uapi/linux/sched.h>
 
 struct proc_ns_operations;
 
@@ -37,6 +38,7 @@ extern const struct proc_ns_operations timens_operations;
 extern const struct proc_ns_operations timens_for_children_operations;
 
 struct ns_common {
+	u32 ns_type;
 	struct dentry *stashed;
 	const struct proc_ns_operations *ops;
 	unsigned int inum;
@@ -51,7 +53,7 @@ struct ns_common {
 	};
 };
 
-int __ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops, int inum);
+int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_operations *ops, int inum);
 void __ns_common_free(struct ns_common *ns);
 
 #define to_ns_common(__ns)                                    \
@@ -106,10 +108,28 @@ void __ns_common_free(struct ns_common *ns);
 		struct user_namespace *:   (IS_ENABLED(CONFIG_USER_NS) ? &userns_operations   : NULL), \
 		struct uts_namespace *:    (IS_ENABLED(CONFIG_UTS_NS)  ? &utsns_operations    : NULL))
 
-#define ns_common_init(__ns) \
-	__ns_common_init(to_ns_common(__ns), to_ns_operations(__ns), (((__ns) == ns_init_ns(__ns)) ? ns_init_inum(__ns) : 0))
-
-#define ns_common_init_inum(__ns, __inum) __ns_common_init(to_ns_common(__ns), to_ns_operations(__ns), __inum)
+#define ns_common_type(__ns)                                \
+	_Generic((__ns),                                    \
+		struct cgroup_namespace *: CLONE_NEWCGROUP, \
+		struct ipc_namespace *:    CLONE_NEWIPC,    \
+		struct mnt_namespace *:    CLONE_NEWNS,     \
+		struct net *:              CLONE_NEWNET,    \
+		struct pid_namespace *:    CLONE_NEWPID,    \
+		struct time_namespace *:   CLONE_NEWTIME,   \
+		struct user_namespace *:   CLONE_NEWUSER,   \
+		struct uts_namespace *:    CLONE_NEWUTS)
+
+#define ns_common_init(__ns)                     \
+	__ns_common_init(to_ns_common(__ns),     \
+			 ns_common_type(__ns),   \
+			 to_ns_operations(__ns), \
+			 (((__ns) == ns_init_ns(__ns)) ? ns_init_inum(__ns) : 0))
+
+#define ns_common_init_inum(__ns, __inum)        \
+	__ns_common_init(to_ns_common(__ns),     \
+			 ns_common_type(__ns),   \
+			 to_ns_operations(__ns), \
+			 __inum)
 
 #define ns_common_free(__ns) __ns_common_free(to_ns_common((__ns)))
 
diff --git a/include/linux/nstree.h b/include/linux/nstree.h
index 29ad6402260c..8b8636690473 100644
--- a/include/linux/nstree.h
+++ b/include/linux/nstree.h
@@ -9,19 +9,6 @@
 #include <linux/rculist.h>
 #include <linux/cookie.h>
 
-/**
- * struct ns_tree - Namespace tree
- * @ns_tree: Rbtree of namespaces of a particular type
- * @ns_list: Sequentially walkable list of all namespaces of this type
- * @ns_tree_lock: Seqlock to protect the tree and list
- */
-struct ns_tree {
-	struct rb_root ns_tree;
-	struct list_head ns_list;
-	seqlock_t ns_tree_lock;
-	int type;
-};
-
 extern struct ns_tree cgroup_ns_tree;
 extern struct ns_tree ipc_ns_tree;
 extern struct ns_tree mnt_ns_tree;
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index 08016f6e0e6f..e81b8e596e4f 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -17,7 +17,6 @@ struct inode;
 struct proc_ns_operations {
 	const char *name;
 	const char *real_ns_name;
-	int type;
 	struct ns_common *(*get)(struct task_struct *task);
 	void (*put)(struct ns_common *ns);
 	int (*install)(struct nsset *nsset, struct ns_common *ns);