From: Catherine Sullivan <csully@google.com>
Date: Mon, 17 May 2021 14:08:14 -0700
Subject: gve: Upgrade memory barrier in poll routine
Patch-mainline: v5.13-rc4
Git-commit: f81781835f0adfae8d701545386030d223efcd6f
References: bsc#1176940
As currently written, if the driver checks for more work (via
gve_tx_poll or gve_rx_poll) before the device posts work and the
irq doorbell is not unmasked
(via iowrite32be(GVE_IRQ_ACK | GVE_IRQ_EVENT, ...)) before the device
attempts to raise an interrupt, an interrupt is lost and this could
potentially lead to the traffic being completely halted. For
example, if a tx queue has already been stopped, the driver won't get
the chance to complete work and egress will be halted.
We need a full memory barrier in the poll
routine to ensure that the irq doorbell is unmasked before the driver
checks for more work.
Fixes: f5cedc84a30d ("gve: Add transmit and receive support")
Signed-off-by: Catherine Sullivan <csully@google.com>
Signed-off-by: David Awogbemila <awogbemila@google.com>
Acked-by: Willem de Brujin <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/net/ethernet/google/gve/gve_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -180,7 +180,7 @@ static int gve_napi_poll(struct napi_str
/* Double check we have no extra work.
* Ensure unmask synchronizes with checking for work.
*/
- dma_rmb();
+ mb();
if (block->tx)
reschedule |= gve_tx_poll(block, -1);
if (block->rx)