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authorLendacky, Thomas <Thomas.Lendacky@amd.com>2015-10-26 17:13:54 -0500
committerDavid S. Miller <davem@davemloft.net>2015-10-27 19:49:22 -0700
commit20986ed826cbb36bb8f2d77f872e3c52d8d30647 (patch)
treeb901d1387064b7a4710227081ee23083a421d6e1
parent8ce675ff39b9958d1c10f86cf58e357efaafc856 (diff)
downloadlinux-stericsson-20986ed826cbb36bb8f2d77f872e3c52d8d30647.tar.gz
amd-xgbe: Fix race between access of desc and desc index
During Tx cleanup it's still possible for the descriptor data to be read ahead of the descriptor index. A memory barrier is required between the read of the descriptor index and the start of the Tx cleanup loop. This allows a change to a lighter-weight barrier in the Tx transmit routine just before updating the current descriptor index. Since the memory barrier does result in extra overhead on arm64, keep the previous change to not chase the current descriptor value. This prevents the execution of the barrier for each loop performed. Suggested-by: Alexander Duyck <alexander.duyck@gmail.com> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/ethernet/amd/xgbe/xgbe-dev.c2
-rw-r--r--drivers/net/ethernet/amd/xgbe/xgbe-drv.c4
2 files changed, 5 insertions, 1 deletions
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
index e9ab8b9f3b9c..f672dba345f7 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
@@ -1595,7 +1595,7 @@ static void xgbe_dev_xmit(struct xgbe_channel *channel)
packet->rdesc_count, 1);
/* Make sure ownership is written to the descriptor */
- wmb();
+ smp_wmb();
ring->cur = cur_index + 1;
if (!packet->skb->xmit_more ||
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index d2b77d985441..dde0486667e0 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -1816,6 +1816,10 @@ static int xgbe_tx_poll(struct xgbe_channel *channel)
return 0;
cur = ring->cur;
+
+ /* Be sure we get ring->cur before accessing descriptor data */
+ smp_rmb();
+
txq = netdev_get_tx_queue(netdev, channel->queue_index);
while ((processed < XGBE_TX_DESC_MAX_PROC) &&