From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH PATCH net v2 5/9] hv_netvsc: fix race in napi poll when rescheduling Date: Fri, 2 Mar 2018 13:49:05 -0800 Message-ID: <20180302214909.26066-6-sthemmin@microsoft.com> References: <20180302214909.26066-1-sthemmin@microsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: devel@linuxdriverproject.org, netdev@vger.kernel.org To: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com Return-path: In-Reply-To: <20180302214909.26066-1-sthemmin@microsoft.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" List-Id: netdev.vger.kernel.org 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 --- 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 ff97a85b2e9d..4237cedc4f08 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -1207,9 +1207,10 @@ 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 */ -- 2.16.1