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authorBenjamin Poirier <bpoirier@suse.com>2016-11-07 17:57:56 +0800
committerDavid S. Miller <davem@davemloft.net>2016-11-09 13:31:10 -0500
commitd667f78514c656a6a8bf0b3d6134a7fe5cd4d317 (patch)
tree7ed61aa920207a95b8f1bbcfb89d6623f0336e37 /drivers/net/ethernet/brocade
parentf91d718156fe93d0cf684cacf5f247c35a825d79 (diff)
bna: Add synchronization for tx ring.
We received two reports of BUG_ON in bnad_txcmpl_process() where hw_consumer_index appeared to be ahead of producer_index. Out of order write/read of these variables could explain these reports. bnad_start_xmit(), as a producer of tx descriptors, has a few memory barriers sprinkled around writes to producer_index and the device's doorbell but they're not paired with anything in bnad_txcmpl_process(), a consumer. Since we are synchronizing with a device, we must use mandatory barriers, not smp_*. Also, I didn't see the purpose of the last smp_mb() in bnad_start_xmit(). Signed-off-by: Benjamin Poirier <bpoirier@suse.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/brocade')
-rw-r--r--drivers/net/ethernet/brocade/bna/bnad.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/ethernet/brocade/bna/bnad.c b/drivers/net/ethernet/brocade/bna/bnad.c
index f9df4b5ae90e..f42f672b0e7e 100644
--- a/drivers/net/ethernet/brocade/bna/bnad.c
+++ b/drivers/net/ethernet/brocade/bna/bnad.c
@@ -177,6 +177,7 @@ bnad_txcmpl_process(struct bnad *bnad, struct bna_tcb *tcb)
return 0;
hw_cons = *(tcb->hw_consumer_index);
+ rmb();
cons = tcb->consumer_index;
q_depth = tcb->q_depth;
@@ -3094,7 +3095,7 @@ bnad_start_xmit(struct sk_buff *skb, struct net_device *netdev)
BNA_QE_INDX_INC(prod, q_depth);
tcb->producer_index = prod;
- smp_mb();
+ wmb();
if (unlikely(!test_bit(BNAD_TXQ_TX_STARTED, &tcb->flags)))
return NETDEV_TX_OK;
@@ -3102,7 +3103,6 @@ bnad_start_xmit(struct sk_buff *skb, struct net_device *netdev)
skb_tx_timestamp(skb);
bna_txq_prod_indx_doorbell(tcb);
- smp_mb();
return NETDEV_TX_OK;
}