diff options
| author |   Eric Dumazet <edumazet@google.com> | 2016-11-19 14:57:11 -0800 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2016-11-21 11:32:34 -0500 |
| commit | b668534c1d9b80f4cda4d761eb11d3a6c9f4ced8 (patch) | |
| tree | 5d65a634c526447fdc64421f1bc5102cd7da18df /drivers/net/ethernet/broadcom/bnx2.c | |
| parent | udp: avoid one cache line miss in recvmsg() (diff) | |
| download | linux-dev-b668534c1d9b80f4cda4d761eb11d3a6c9f4ced8.tar.xz linux-dev-b668534c1d9b80f4cda4d761eb11d3a6c9f4ced8.zip | |
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 '')
| -rw-r--r-- | drivers/net/ethernet/broadcom/bnx2.c | 17 |
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; |