From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH net 3/3] netvsc: fix RCU warning from set_multicast Date: Mon, 5 Jun 2017 14:10:10 -0700 Message-ID: <20170605211010.9571-4-sthemmin@microsoft.com> References: <20170605211010.9571-1-sthemmin@microsoft.com> Cc: netdev@vger.kernel.org, Stephen Hemminger To: davem@davemloft.net Return-path: Received: from mail-pg0-f50.google.com ([74.125.83.50]:33281 "EHLO mail-pg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751153AbdFEVK3 (ORCPT ); Mon, 5 Jun 2017 17:10:29 -0400 Received: by mail-pg0-f50.google.com with SMTP id f185so25507683pgc.0 for ; Mon, 05 Jun 2017 14:10:28 -0700 (PDT) In-Reply-To: <20170605211010.9571-1-sthemmin@microsoft.com> Sender: netdev-owner@vger.kernel.org List-ID: do_set_multicast runs in a work queue and therefore is not holding RCU read lock. This causes: WARNING: suspicious RCU usage 4.12.0-rc2-net-00284-ge23454766d55-dirty #2 Not tainted ----------------------------- drivers/net/hyperv/netvsc_drv.c:65 suspicious rcu_dereference_check() usage! Fix by acquiring rtnl_lock which is ok in the work queue context. Better fix is to move do_set_mulitcast into rndis_filter.c but that has more complex impacts, so hold off until net-next. Signed-off-by: Stephen Hemminger --- drivers/net/hyperv/netvsc_drv.c | 34 ++++++++++++++++++---------------- 1 file changed, 18 insertions(+), 16 deletions(-) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 252e5d52d17e..ba5c4d037b76 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -62,24 +62,26 @@ static void do_set_multicast(struct work_struct *w) container_of(w, struct net_device_context, work); struct hv_device *device_obj = ndevctx->device_ctx; struct net_device *ndev = hv_get_drvdata(device_obj); - struct netvsc_device *nvdev = rcu_dereference(ndevctx->nvdev); + struct netvsc_device *nvdev; struct rndis_device *rdev; - if (!nvdev) - return; - - rdev = nvdev->extension; - if (rdev == NULL) - return; - - if (ndev->flags & IFF_PROMISC) - rndis_filter_set_packet_filter(rdev, - NDIS_PACKET_TYPE_PROMISCUOUS); - else - rndis_filter_set_packet_filter(rdev, - NDIS_PACKET_TYPE_BROADCAST | - NDIS_PACKET_TYPE_ALL_MULTICAST | - NDIS_PACKET_TYPE_DIRECTED); + rtnl_lock(); + nvdev = rtnl_dereference(ndevctx->nvdev); + if (nvdev) + rdev = nvdev->extension; + + if (rdev) { + if (ndev->flags & IFF_PROMISC) + rndis_filter_set_packet_filter(rdev, + NDIS_PACKET_TYPE_PROMISCUOUS); + else + rndis_filter_set_packet_filter(rdev, + NDIS_PACKET_TYPE_BROADCAST | + NDIS_PACKET_TYPE_ALL_MULTICAST | + NDIS_PACKET_TYPE_DIRECTED); + } + } + rtnl_unlock(); } static void netvsc_set_multicast_list(struct net_device *net) -- 2.11.0