{"id":2231614,"url":"http://patchwork.ozlabs.org/api/patches/2231614/?format=json","web_url":"http://patchwork.ozlabs.org/project/openvswitch/patch/20260430233848.440994-2-i.maximets@ovn.org/","project":{"id":47,"url":"http://patchwork.ozlabs.org/api/projects/47/?format=json","name":"Open vSwitch","link_name":"openvswitch","list_id":"ovs-dev.openvswitch.org","list_email":"ovs-dev@openvswitch.org","web_url":"http://openvswitch.org/","scm_url":"git@github.com:openvswitch/ovs.git","webscm_url":"https://github.com/openvswitch/ovs","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260430233848.440994-2-i.maximets@ovn.org>","list_archive_url":null,"date":"2026-04-30T23:38:37","name":"[ovs-dev,net,v2,1/2] openvswitch: vport: fix self-deadlock on release of tunnel ports","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"57dfc576a267b0224ba92f1c523a39cbc024d30a","submitter":{"id":76798,"url":"http://patchwork.ozlabs.org/api/people/76798/?format=json","name":"Ilya Maximets","email":"i.maximets@ovn.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/openvswitch/patch/20260430233848.440994-2-i.maximets@ovn.org/mbox/","series":[{"id":502405,"url":"http://patchwork.ozlabs.org/api/series/502405/?format=json","web_url":"http://patchwork.ozlabs.org/project/openvswitch/list/?series=502405","date":"2026-04-30T23:38:37","name":"openvswitch: fix self-deadlock on release of tunnel vports","version":2,"mbox":"http://patchwork.ozlabs.org/series/502405/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2231614/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2231614/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","dev@openvswitch.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","ovs-dev@lists.linuxfoundation.org"],"Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=openvswitch.org\n (client-ip=2605:bc80:3010::137; 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Miller\" ","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Errors-To":"ovs-dev-bounces@openvswitch.org","Sender":"\"dev\" "},"content":"vports are used concurrently and protected by RCU, so netdev_put()\nmust happen after the RCU grace period. So, either in an RCU call or\nafter the synchronize_net(). The rtnl_delete_link() must happen under\nRTNL and so can't be executed in RCU context. Calling synchronize_net()\nwhile holding RTNL is not a good idea for performance and system\nstability under load in general, so calling netdev_put() in RCU call\nis the right solution here.\n\nHowever,\nwhen the device is deleted, rtnl_unlock() will call netdev_run_todo()\nand block until all the references are gone. In the current code this\nmeans that we never reach the call_rcu() and the vport is never freed\nand the reference is never released, causing a self-deadlock on device\nremoval.\n\nFix that by moving the rcu_call() before the rtnl_unlock(), so the\nscheduled RCU callback will be executed when synchronize_net() is\ncalled from the rtnl_unlock()->netdev_run_todo() while the RTNL itself\nis already released.\n\nFixes: 6931d21f87bc (\"openvswitch: defer tunnel netdev_put to RCU release\")\nCc: stable@vger.kernel.org\nAcked-by: Eelco Chaudron \nSigned-off-by: Ilya Maximets \n---\n net/openvswitch/vport-netdev.c | 6 +++++-\n 1 file changed, 5 insertions(+), 1 deletion(-)","diff":"diff --git a/net/openvswitch/vport-netdev.c b/net/openvswitch/vport-netdev.c\nindex 12055af832dc0..a1df551e915bc 100644\n--- a/net/openvswitch/vport-netdev.c\n+++ b/net/openvswitch/vport-netdev.c\n@@ -196,9 +196,13 @@ void ovs_netdev_tunnel_destroy(struct vport *vport)\n \t */\n \tif (vport->dev->reg_state == NETREG_REGISTERED)\n \t\trtnl_delete_link(vport->dev, 0, NULL);\n-\trtnl_unlock();\n \n+\t/* We can't put the device reference yet, since it can still be in\n+\t * use, but rtnl_unlock()->netdev_run_todo() will block until all\n+\t * the references are released, so the RCU call must be before it.\n+\t */\n \tcall_rcu(&vport->rcu, vport_netdev_free);\n+\trtnl_unlock();\n }\n EXPORT_SYMBOL_GPL(ovs_netdev_tunnel_destroy);\n \n","prefixes":["ovs-dev","net","v2","1/2"]}