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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>
This commit is contained in:
Stephen Hemminger 2018-03-02 13:49:05 -08:00 committed by David S. Miller
parent a7483ec026
commit d64e38ae69
1 changed files with 3 additions and 2 deletions
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5
drivers/net/hyperv/netvsc.c
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@ -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 */