From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stephen Hemminger , "David S. Miller" Subject: [PATCH 4.14 025/165] hv_netvsc: fix race in napi poll when rescheduling Date: Thu, 24 May 2018 11:37:11 +0200 Message-Id: <20180524093622.999356098@linuxfoundation.org> In-Reply-To: <20180524093621.979359379@linuxfoundation.org> References: <20180524093621.979359379@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- drivers/net/hyperv/netvsc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -1205,9 +1205,10 @@ int netvsc_poll(struct napi_struct *napi 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 */