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| author |   Liran Alon <liran.alon@oracle.com> | 2020-01-03 18:44:59 +0200 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2020-01-03 12:40:53 -0800 |
| commit | b54ef37b1ce892fdf6b632d566246d2f2f539910 (patch) | |
| tree | b52c82984379aaab718a28a7004f9f6245abb374 /drivers/net/ethernet/google/gve/gve_tx.c | |
| parent | net: phylink: fix failure to register on x86 systems (diff) | |
| download | linux-dev-b54ef37b1ce892fdf6b632d566246d2f2f539910.tar.xz linux-dev-b54ef37b1ce892fdf6b632d566246d2f2f539910.zip | |
net: Google gve: Remove dma_wmb() before ringing doorbell
Current code use dma_wmb() to ensure Rx/Tx descriptors are visible
to device before writing to doorbell.
However, these dma_wmb() are wrong and unnecessary. Therefore,
they should be removed.
iowrite32be() called from gve_rx_write_doorbell()/gve_tx_put_doorbell()
should guaratee that all previous writes to WB/UC memory is visible to
device before the write done by iowrite32be().
E.g. On ARM64, iowrite32be() calls __iowmb() which expands to dma_wmb()
and only then calls __raw_writel().
Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/google/gve/gve_tx.c')
| -rw-r--r-- | drivers/net/ethernet/google/gve/gve_tx.c | 6 |
1 files changed, 0 insertions, 6 deletions
diff --git a/drivers/net/ethernet/google/gve/gve_tx.c b/drivers/net/ethernet/google/gve/gve_tx.c index f4889431f9b7..d0244feb0301 100644 --- a/drivers/net/ethernet/google/gve/gve_tx.c +++ b/drivers/net/ethernet/google/gve/gve_tx.c @@ -487,10 +487,6 @@ netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev) * may have added descriptors without ringing the doorbell. */ - /* Ensure tx descs from a prior gve_tx are visible before - * ringing doorbell. - */ - dma_wmb(); gve_tx_put_doorbell(priv, tx->q_resources, tx->req); return NETDEV_TX_BUSY; } @@ -505,8 +501,6 @@ netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev) if (!netif_xmit_stopped(tx->netdev_txq) && netdev_xmit_more()) return NETDEV_TX_OK; - /* Ensure tx descs are visible before ringing doorbell */ - dma_wmb(); gve_tx_put_doorbell(priv, tx->q_resources, tx->req); return NETDEV_TX_OK; } |