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e100: Use dma_rmb/wmb where appropriate 

Reduce the CPU overhead for transmit and receive by using lightweight dma_
barriers instead of full barriers where they are applicable.

Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2015-04-08 18:49:49 -07:00 committed by David S. Miller
parent 67317166dd
commit c335869fb9
1 changed files with 3 additions and 3 deletions
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6
drivers/net/ethernet/intel/e100.c
View File

@ -899,7 +899,7 @@ static int e100_exec_cb(struct nic *nic, struct sk_buff *skb,
/* Order is important otherwise we'll be in a race with h/w:
* set S-bit in current first, then clear S-bit in previous. */
cb->command |= cpu_to_le16(cb_s);
wmb();
dma_wmb();
cb->prev->command &= cpu_to_le16(~cb_s);
while (nic->cb_to_send != nic->cb_to_use) {
@ -1843,7 +1843,7 @@ static int e100_tx_clean(struct nic *nic)
for (cb = nic->cb_to_clean;
cb->status & cpu_to_le16(cb_complete);
cb = nic->cb_to_clean = cb->next) {
rmb(); /* read skb after status */
dma_rmb(); /* read skb after status */
netif_printk(nic, tx_done, KERN_DEBUG, nic->netdev,
"cb[%d]->status = 0x%04X\n",
(int)(((void*)cb - (void*)nic->cbs)/sizeof(struct cb)),
@ -1993,7 +1993,7 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
netif_printk(nic, rx_status, KERN_DEBUG, nic->netdev,
"status=0x%04X\n", rfd_status);
rmb(); /* read size after status bit */
dma_rmb(); /* read size after status bit */
/* If data isn't ready, nothing to indicate */
if (unlikely(!(rfd_status & cb_complete))) {