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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2017-04-18 01:37:05 +0300
committerDavid S. Miller <davem@davemloft.net>2017-04-18 21:11:09 +0300
commitccaf725a1fd7904ed3e771ed178c2aa1ccb21509 (patch)
tree8f202223c260b201710312cd3c42411463638a3d /drivers/net/ethernet/faraday
parent33de693248b45640c0d894c2454a9909f2e81ffd (diff)
downloadlinux-ccaf725a1fd7904ed3e771ed178c2aa1ccb21509.tar.xz
ftgmac100: Fix potential ordering issue in NAPI poll
We need to ensure the loads from the descriptor are done after the MMIO store clearing the interrupts has completed, otherwise we might still miss work. A read back from the MMIO register will "push" the posted store and ioread32 has a barrier on weakly aordered architectures that will order subsequent accesses. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/faraday')
-rw-r--r--drivers/net/ethernet/faraday/ftgmac100.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
index 45b8267b81b7..95bf5e89cfd1 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -1349,6 +1349,13 @@ static int ftgmac100_poll(struct napi_struct *napi, int budget)
*/
iowrite32(FTGMAC100_INT_RXTX,
priv->base + FTGMAC100_OFFSET_ISR);
+
+ /* Push the above (and provides a barrier vs. subsequent
+ * reads of the descriptor).
+ */
+ ioread32(priv->base + FTGMAC100_OFFSET_ISR);
+
+ /* Check RX and TX descriptors for more work to do */
if (ftgmac100_check_rx(priv) ||
ftgmac100_tx_buf_cleanable(priv))
return budget;