diff mbox series

[net,4/5] gve: Upgrade memory barrier in poll routine

Message ID 20210517210815.3751286-5-awogbemila@google.com (mailing list archive)
State Accepted
Commit f81781835f0adfae8d701545386030d223efcd6f
Delegated to: Netdev Maintainers
Headers show
Series GVE bug fixes | expand

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netdev/cc_maintainers fail 3 blamed authors not CCed: sagis@google.com davem@davemloft.net jonolson@google.com; 8 maintainers not CCed: patricion@google.com gustavoars@kernel.org kuozhao@google.com sagis@google.com jonolson@google.com yangchun@google.com davem@davemloft.net kuba@kernel.org
netdev/source_inline success Was 0 now: 0
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netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
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netdev/checkpatch warning WARNING: memory barrier without comment
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
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Commit Message

David Awogbemila May 17, 2021, 9:08 p.m. UTC 
From: Catherine Sullivan <csully@google.com>

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>
---
 drivers/net/ethernet/google/gve/gve_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 21a5d058dab4..bbc423e93122 100644
--- 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_struct *napi, int budget)
 	/* 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)