diff options
| author | Benjamin Poirier <bpoirier@suse.com> | 2016-11-07 17:57:56 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-11-09 13:31:10 -0500 |
| commit | d667f78514c656a6a8bf0b3d6134a7fe5cd4d317 (patch) | |
| tree | 7ed61aa920207a95b8f1bbcfb89d6623f0336e37 /drivers | |
| parent | f91d718156fe93d0cf684cacf5f247c35a825d79 (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')
| -rw-r--r-- | drivers/net/ethernet/brocade/bna/bnad.c | 4 |
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; } |