linux-kernel - [PATCH net] hv_netvsc: Fix napi reschedule while receive completion is busy

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Date:   Mon,  9 Jul 2018 16:43:19 +0000
From:   Haiyang Zhang <haiyangz@...uxonhyperv.com>
To:     davem@...emloft.net, netdev@...r.kernel.org
Cc:     haiyangz@...rosoft.com, kys@...rosoft.com, sthemmin@...rosoft.com,
        olaf@...fle.de, vkuznets@...hat.com, devel@...uxdriverproject.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net] hv_netvsc: Fix napi reschedule while receive completion is busy

From: Haiyang Zhang <haiyangz@...rosoft.com>

If out ring is full temporarily and receive completion cannot go out,
we may still need to reschedule napi if other conditions are met.
Otherwise the napi poll might be stopped forever, and cause network
disconnect.

Fixes: 7426b1a51803 ("netvsc: optimize receive completions")
Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
---
 drivers/net/hyperv/netvsc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 8e9d0ee1572b..caaf5054f446 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1285,14 +1285,14 @@ int netvsc_poll(struct napi_struct *napi, int budget)
 		nvchan->desc = hv_pkt_iter_next(channel, nvchan->desc);
 	}
 
-	/* If send of pending receive completions suceeded
-	 *   and did not exhaust NAPI budget this time
+	send_recv_completions(ndev, net_device, nvchan);
+
+	/* If it did not exhaust NAPI budget this time
 	 *   and not doing busy poll
 	 * then re-enable host interrupts
 	 *     and reschedule if ring is not empty.
 	 */
-	if (send_recv_completions(ndev, net_device, nvchan) == 0 &&
-	    work_done < budget &&
+	if (work_done < budget &&
 	    napi_complete_done(napi, work_done) &&
 	    hv_end_read(&channel->inbound) &&
 	    napi_schedule_prep(napi)) {
-- 
2.17.1