Commit d64e38ae authored Mar 02, 2018 by Stephen Hemminger Committed by David S. Miller Mar 04, 2018

hv_netvsc: fix race in napi poll when rescheduling



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 <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent a7483ec0

drivers/net/hyperv/netvsc.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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 */