From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH net-stable 14/24] hv_netvsc: fix race in napi poll when rescheduling Date: Mon, 14 May 2018 15:32:13 -0700 Message-ID: <20180514223223.25433-15-sthemmin@microsoft.com> References: <20180514223223.25433-1-sthemmin@microsoft.com> Cc: netdev@vger.kernel.org, Stephen Hemminger , Stephen Hemminger To: davem@davemloft.net Return-path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:33692 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752265AbeENWcv (ORCPT ); Mon, 14 May 2018 18:32:51 -0400 Received: by mail-pf0-f196.google.com with SMTP id a20-v6so2742969pfo.0 for ; Mon, 14 May 2018 15:32:51 -0700 (PDT) In-Reply-To: <20180514223223.25433-1-sthemmin@microsoft.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Stephen Hemminger commit d64e38ae690e3337db0d38d9b149a193a1646c4b upstream There is a race between napi_reschedule and re-enabling interrupts which could lead to missed host interrrupts. This occurs when interrupts are re-enabled (hv_end_read) and vmbus irq callback (netvsc_channel_cb) has already scheduled NAPI. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- drivers/net/hyperv/netvsc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index b7720b65f5d6..7e0eb99571af 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -1205,9 +1205,10 @@ int netvsc_poll(struct napi_struct *napi, int budget) if (send_recv_completions(ndev, net_device, nvchan) == 0 && work_done < budget && napi_complete_done(napi, work_done) && - hv_end_read(&channel->inbound)) { + hv_end_read(&channel->inbound) && + napi_schedule_prep(napi)) { hv_begin_read(&channel->inbound); - napi_reschedule(napi); + __napi_schedule(napi); } /* Driver may overshoot since multiple packets per descriptor */ -- 2.17.0