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Commit c335869f authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller
Browse files

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: default avatarAlexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 67317166

drivers/net/ethernet/intel/e100.c

+3 −3
Original line number Diff line number Diff line
@@ -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))) {