Do some memory barrier changes for safety/perfomance: Don't need read after update to index, mmiowb() followed by read at end of irq is sufficient. Signed-off-by: Stephn Hemminger --- drivers/net/sky2.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) --- 2.6.21-rc1.orig/drivers/net/sky2.c 2007-05-14 12:10:22.000000000 -0700 +++ 2.6.21-rc1/drivers/net/sky2.c 2007-05-14 12:10:24.000000000 -0700 @@ -844,10 +844,12 @@ static inline struct tx_ring_info *tx_le /* Update chip's next pointer */ static inline void sky2_put_idx(struct sky2_hw *hw, unsigned q, u16 idx) { - q = Y2_QADDR(q, PREF_UNIT_PUT_IDX); + /* Make sure write' to descriptors are complete before we tell hardware */ wmb(); - sky2_write16(hw, q, idx); - sky2_read16(hw, q); + sky2_write16(hw, Y2_QADDR(q, PREF_UNIT_PUT_IDX), idx); + + /* Synchronize I/O on since next processor may write to tail */ + mmiowb(); } @@ -979,6 +981,7 @@ stopped: /* reset the Rx prefetch unit */ sky2_write32(hw, Y2_QADDR(rxq, PREF_UNIT_CTRL), PREF_UNIT_RST_SET); + mmiowb(); } /* Clean out receive buffer area, assumes receiver hardware stopped */ @@ -1198,7 +1201,7 @@ static int sky2_rx_start(struct sky2_por } /* Tell chip about available buffers */ - sky2_write16(hw, Y2_QADDR(rxq, PREF_UNIT_PUT_IDX), sky2->rx_put); + sky2_put_idx(hw, rxq, sky2->rx_put); return 0; nomem: sky2_rx_clean(sky2); @@ -1540,6 +1543,8 @@ static void sky2_tx_complete(struct sky2 } sky2->tx_cons = idx; + smp_mb(); + if (tx_avail(sky2) > MAX_SKB_TX_LE + 4) netif_wake_queue(dev); } @@ -2218,6 +2223,7 @@ force_update: /* Fully processed status ring so clear irq */ sky2_write32(hw, STAT_CTRL, SC_STAT_CLR_IRQ); + mmiowb(); exit_loop: if (buf_write[0]) { @@ -2442,6 +2448,7 @@ static int sky2_poll(struct net_device * if (work_done < work_limit) { netif_rx_complete(dev0); + /* end of interrupt, re-enables also acts as I/O synchronization */ sky2_read32(hw, B0_Y2_SP_LISR); return 0; } else { -- Stephen Hemminger - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html