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From: Sameeh Jubran <sameehj@amazon.com>
Date: Sun, 15 Sep 2019 17:29:44 +0300
Subject: [PATCH] net: ena: don't wake up tx queue when down
Origin: https://git.kernel.org/linus/a53651ec93a8d7ab5b26c5390e0c389048b4b4b6
Bug-Debian: https://bugs.debian.org/941291
There is a race condition that can occur when calling ena_down().
The ena_clean_tx_irq() - which is a part of the napi handler -
function might wake up the tx queue when the queue is supposed
to be down (during recovery or changing the size of the queues
for example) This causes the ena_start_xmit() function to trigger
and possibly try to access the destroyed queues.
The race is illustrated below:
Flow A: Flow B(napi handler)
ena_down()
netif_carrier_off()
netif_tx_disable()
ena_clean_tx_irq()
netif_tx_wake_queue()
ena_napi_disable_all()
ena_destroy_all_io_queues()
After these flows the tx queue is active and ena_start_xmit() accesses
the destroyed queue which leads to a kernel panic.
fixes: 1738cd3ed342 (net: ena: Add a driver for Amazon Elastic Network Adapters (ENA))
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/ethernet/amazon/ena/ena_netdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 664e3ed97ea9..d118ed4c57ce 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -823,7 +823,8 @@ static int ena_clean_tx_irq(struct ena_ring *tx_ring, u32 budget)
above_thresh =
ena_com_sq_have_enough_space(tx_ring->ena_com_io_sq,
ENA_TX_WAKEUP_THRESH);
- if (netif_tx_queue_stopped(txq) && above_thresh) {
+ if (netif_tx_queue_stopped(txq) && above_thresh &&
+ test_bit(ENA_FLAG_DEV_UP, &tx_ring->adapter->flags)) {
netif_tx_wake_queue(txq);
u64_stats_update_begin(&tx_ring->syncp);
tx_ring->tx_stats.queue_wakeup++;
--
2.17.1
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