netdev - [patch net-next v3 7/7] devlink: document devlink_rel_nested_in

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231013121029.353351-8-jiri@resnulli.us>
Date: Fri, 13 Oct 2023 14:10:29 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: netdev@...r.kernel.org
Cc: kuba@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net,
	edumazet@...gle.com
Subject: [patch net-next v3 7/7] devlink: document devlink_rel_nested_in_notify() function

From: Jiri Pirko <jiri@...dia.com>

Add a documentation for devlink_rel_nested_in_notify() describing the
devlink instance locking consequences.

Signed-off-by: Jiri Pirko <jiri@...dia.com>
---
v2->v3:
- new patch
---
 net/devlink/core.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/net/devlink/core.c b/net/devlink/core.c
index 655903ddbdfd..6984877e9f10 100644
--- a/net/devlink/core.c
+++ b/net/devlink/core.c
@@ -168,6 +168,20 @@ int devlink_rel_nested_in_add(u32 *rel_index, u32 devlink_index,
 	return 0;
 }
 
+/**
+ * devlink_rel_nested_in_notify - Notify the object this devlink
+ *				  instance is nested in.
+ * @devlink: devlink
+ *
+ * This is called upon network namespace change of devlink instance.
+ * In case this devlink instance is nested in another devlink object,
+ * a notification of a change of this object should be sent
+ * over netlink. The parent devlink instance lock needs to be
+ * taken during the notification preparation.
+ * However, since the devlink lock of nested instance is held here,
+ * we would end with wrong devlink instance lock ordering and
+ * deadlock. Therefore the work is utilized to avoid that.
+ */
 void devlink_rel_nested_in_notify(struct devlink *devlink)
 {
 	struct devlink_rel *rel = devlink->rel;
-- 
2.41.0