4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
[ 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 <sthemmin@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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 */
