From: Stephen Hemminger <stephen@networkplumber•org>
To: kys@microsoft•com, haiyangz@microsoft•com, sthemmin@microsoft•com
Cc: devel@linuxdriverproject•org, netdev@vger•kernel.org
Subject: [PATCH net 5/9] hv_netvsc: fix race in napi poll when rescheduling
Date: Thu, 1 Mar 2018 10:27:52 -0800 [thread overview]
Message-ID: <20180301182756.23027-6-sthemmin@microsoft.com> (raw)
In-Reply-To: <20180301182756.23027-1-sthemmin@microsoft.com>
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>
---
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
next prev parent reply other threads:[~2018-03-01 18:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 18:27 [PATCH net 0/9] hv_netvsc: minor bug fixes Stephen Hemminger
2018-03-01 18:27 ` [PATCH net 1/9] hv_netvsc: avoid retry on send during shutdown Stephen Hemminger
2018-03-01 18:27 ` [PATCH net 2/9] hv_netvsc: only wake transmit queue if link is up Stephen Hemminger
2018-03-01 18:27 ` [PATCH net 3/9] hv_netvsc: fix error unwind handling if vmbus_open fails Stephen Hemminger
2018-03-01 18:27 ` [PATCH net 4/9] hv_netvsc: cancel subchannel setup before halting device Stephen Hemminger
2018-03-01 18:27 ` Stephen Hemminger [this message]
2018-03-01 18:27 ` [PATCH net 6/9] hv_netvsc: use napi_schedule_irqoff Stephen Hemminger
2018-03-01 18:27 ` [PATCH net 7/9] hv_netvsc: don't need full irqsave for request_lock Stephen Hemminger
2018-03-01 18:27 ` [PATCH net 8/9] hv_netvsc: propagate rx filters to VF Stephen Hemminger
2018-03-01 21:56 ` Jakub Kicinski
2018-03-01 23:46 ` Stephen Hemminger
2018-03-01 18:27 ` [PATCH net 9/9] hv_netvsc: defer queue selection " Stephen Hemminger
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