[PATCH 07/17] nstree: use guards for ns_tree_lock

Christian Brauner
2025-11-10T15:09:18Z

Make use of the guard infrastructure for ns_tree_lock.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
kernel/nstree.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/kernel/nstree.c b/kernel/nstree.c
index 476dd738d653..5270e0fa67a2 100644
--- 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;
}

--
2.47.3