4.14-stable review patch. If anyone has any objections, please let me know.
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From: Stephen Hemminger stephen@networkplumber.org
[ 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@microsoft.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 */