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authorEric Dumazet <edumazet@google.com>2016-11-19 14:57:11 -0800
committerDavid S. Miller <davem@davemloft.net>2016-11-21 11:32:34 -0500
commitb668534c1d9b80f4cda4d761eb11d3a6c9f4ced8 (patch)
tree5d65a634c526447fdc64421f1bc5102cd7da18df /drivers/net/ethernet/broadcom
parentd21dbdfe0afb5195607d207f894fe86d5b322d46 (diff)
bnx2: use READ_ONCE() instead of barrier()
barrier() is a big hammer compared to READ_ONCE(), and requires comments explaining what is protected. READ_ONCE() is more precise and compiler should generate better overall code. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/broadcom')
-rw-r--r--drivers/net/ethernet/broadcom/bnx2.c17
1 files changed, 5 insertions, 12 deletions
diff --git a/drivers/net/ethernet/broadcom/bnx2.c b/drivers/net/ethernet/broadcom/bnx2.c
index 9960a9249dc0..d5d1026be4b7 100644
--- a/drivers/net/ethernet/broadcom/bnx2.c
+++ b/drivers/net/ethernet/broadcom/bnx2.c
@@ -254,13 +254,10 @@ static inline u32 bnx2_tx_avail(struct bnx2 *bp, struct bnx2_tx_ring_info *txr)
{
u32 diff;
- /* Tell compiler to fetch tx_prod and tx_cons from memory. */
- barrier();
-
/* The ring uses 256 indices for 255 entries, one of them
* needs to be skipped.
*/
- diff = txr->tx_prod - txr->tx_cons;
+ diff = READ_ONCE(txr->tx_prod) - READ_ONCE(txr->tx_cons);
if (unlikely(diff >= BNX2_TX_DESC_CNT)) {
diff &= 0xffff;
if (diff == BNX2_TX_DESC_CNT)
@@ -2839,10 +2836,8 @@ bnx2_get_hw_tx_cons(struct bnx2_napi *bnapi)
{
u16 cons;
- /* Tell compiler that status block fields can change. */
- barrier();
- cons = *bnapi->hw_tx_cons_ptr;
- barrier();
+ cons = READ_ONCE(*bnapi->hw_tx_cons_ptr);
+
if (unlikely((cons & BNX2_MAX_TX_DESC_CNT) == BNX2_MAX_TX_DESC_CNT))
cons++;
return cons;
@@ -3141,10 +3136,8 @@ bnx2_get_hw_rx_cons(struct bnx2_napi *bnapi)
{
u16 cons;
- /* Tell compiler that status block fields can change. */
- barrier();
- cons = *bnapi->hw_rx_cons_ptr;
- barrier();
+ cons = READ_ONCE(*bnapi->hw_rx_cons_ptr);
+
if (unlikely((cons & BNX2_MAX_RX_DESC_CNT) == BNX2_MAX_RX_DESC_CNT))
cons++;
return cons;