nstree: use guards for ns_tree_lock

Make use of the guard infrastructure for ns_tree_lock.

Link: https://patch.msgid.link/20251110-work-namespace-nstree-fixes-v1-7-e8a9264e0fb9@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/kernel/nstree.c b/kernel/nstree.c
index 476dd738d65393158310237fcb53876f9cd4c593..5270e0fa67a20f6c85d0805d2d199504b3ed3b59 100644 (file)
--- a/kernel/nstree.c
+++ b/kernel/nstree.c
@@ -10,6 +10,14 @@
 
 static __cacheline_aligned_in_smp DEFINE_SEQLOCK(ns_tree_lock);
 
+DEFINE_LOCK_GUARD_0(ns_tree_writer,
+                   write_seqlock(&ns_tree_lock),
+                   write_sequnlock(&ns_tree_lock))
+
+DEFINE_LOCK_GUARD_0(ns_tree_locked_reader,
+                   read_seqlock_excl(&ns_tree_lock),
+                   read_sequnlock_excl(&ns_tree_lock))
+
 static struct ns_tree_root ns_unified_root = { /* protected by ns_tree_lock */
        .ns_rb = RB_ROOT,
        .ns_list_head = LIST_HEAD_INIT(ns_unified_root.ns_list_head),
@@ -193,7 +201,7 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree_root *ns_tree)
 
        VFS_WARN_ON_ONCE(!ns->ns_id);
 
-       write_seqlock(&ns_tree_lock);
+       guard(ns_tree_writer)();
 
        /* Add to per-type tree and list */
        node = ns_tree_node_add(&ns->ns_tree_node, ns_tree, ns_cmp);
@@ -218,7 +226,6 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree_root *ns_tree)
                        VFS_WARN_ON_ONCE(ns != to_ns_common(&init_user_ns));
                }
        }
-       write_sequnlock(&ns_tree_lock);
 
        VFS_WARN_ON_ONCE(node);
 }
@@ -461,9 +468,9 @@ static struct ns_common *lookup_ns_owner_at(u64 ns_id, struct ns_common *owner)
 
        VFS_WARN_ON_ONCE(owner->ns_type != CLONE_NEWUSER);
 
-       read_seqlock_excl(&ns_tree_lock);
-       node = owner->ns_owner_root.ns_rb.rb_node;
+       guard(ns_tree_locked_reader)();
 
+       node = owner->ns_owner_root.ns_rb.rb_node;
        while (node) {
                struct ns_common *ns;
 
@@ -480,7 +487,6 @@ static struct ns_common *lookup_ns_owner_at(u64 ns_id, struct ns_common *owner)
 
        if (ret)
                ret = ns_get_unless_inactive(ret);
-       read_sequnlock_excl(&ns_tree_lock);
        return ret;
 }
 
@@ -648,7 +654,8 @@ static struct ns_common *lookup_ns_id_at(u64 ns_id, int ns_type)
                        return NULL;
        }
 
-       read_seqlock_excl(&ns_tree_lock);
+       guard(ns_tree_locked_reader)();
+
        if (ns_tree)
                node = ns_tree->ns_rb.rb_node;
        else
@@ -677,7 +684,6 @@ static struct ns_common *lookup_ns_id_at(u64 ns_id, int ns_type)
 
        if (ret)
                ret = ns_get_unless_inactive(ret);
-       read_sequnlock_excl(&ns_tree_lock);
        return ret;
 }