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hv_netvsc: fix race that may miss tx queue wakeup

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When the ring buffer is almost full due to RX completion messages, a
TX packet may reach the "low watermark" and cause the queue stopped.
If the TX completion arrives earlier than queue stopping, the wakeup
may be missed.

This patch moves the check for the last pending packet to cover both
EAGAIN and success cases, so the queue will be reliably waked up when
necessary.

Reported-and-tested-by: Stephan Klein <stephan.klein@wegfinder.at>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Haiyang Zhang 2019-04-30 19:29:07 +00:00 committed by David S. Miller
parent ea9866793d
commit 93aa4792c3
1 changed files with 9 additions and 6 deletions
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15
drivers/net/hyperv/netvsc.c
View file

@ -875,12 +875,6 @@ static inline int netvsc_send_pkt(
} else if (ret == -EAGAIN) {
netif_tx_stop_queue(txq);
ndev_ctx->eth_stats.stop_queue++;
if (atomic_read(&nvchan->queue_sends) < 1 &&
!net_device->tx_disable) {
netif_tx_wake_queue(txq);
ndev_ctx->eth_stats.wake_queue++;
ret = -ENOSPC;
}
} else {
netdev_err(ndev,
"Unable to send packet pages %u len %u, ret %d\n",
@ -888,6 +882,15 @@ static inline int netvsc_send_pkt(
ret);
}
if (netif_tx_queue_stopped(txq) &&
atomic_read(&nvchan->queue_sends) < 1 &&
!net_device->tx_disable) {
netif_tx_wake_queue(txq);
ndev_ctx->eth_stats.wake_queue++;
if (ret == -EAGAIN)
ret = -ENOSPC;
}
return ret;
}