diff options
| author | Soren Brinkmann <soren.brinkmann@xilinx.com> | 2014-05-05 00:43:02 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-05-05 23:11:18 +0200 |
| commit | c8ea5a22bd3b27d68ec2f95483ce8bfe7f114933 (patch) | |
| tree | 28ab536723891f977119ac51d2b1dbc00416a2ae /drivers | |
| parent | net: macb: Remove 'unlikely' optimization (diff) | |
| download | linux-c8ea5a22bd3b27d68ec2f95483ce8bfe7f114933.tar.xz linux-c8ea5a22bd3b27d68ec2f95483ce8bfe7f114933.zip | |
net: macb: Fix race between HW and driver
Under "heavy" RX load, the driver cannot handle the descriptors fast
enough. In detail, when a descriptor is consumed, its used flag is
cleared and once the RX budget is consumed all descriptors with a
cleared used flag are prepared to receive more data. Under load though,
the HW may constantly receive more data and use those descriptors with a
cleared used flag before they are actually prepared for next usage.
The head and tail pointers into the RX-ring should always be valid and
we can omit clearing and checking of the used flag.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/ethernet/cadence/macb.c | 10 |
1 files changed, 0 insertions, 10 deletions
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c index 3e13aa31548a..e9daa072ebb4 100644 --- a/drivers/net/ethernet/cadence/macb.c +++ b/drivers/net/ethernet/cadence/macb.c @@ -599,25 +599,16 @@ static void gem_rx_refill(struct macb *bp) { unsigned int entry; struct sk_buff *skb; - struct macb_dma_desc *desc; dma_addr_t paddr; while (CIRC_SPACE(bp->rx_prepared_head, bp->rx_tail, RX_RING_SIZE) > 0) { - u32 addr, ctrl; - entry = macb_rx_ring_wrap(bp->rx_prepared_head); - desc = &bp->rx_ring[entry]; /* Make hw descriptor updates visible to CPU */ rmb(); - addr = desc->addr; - ctrl = desc->ctrl; bp->rx_prepared_head++; - if ((addr & MACB_BIT(RX_USED))) - continue; - if (bp->rx_skbuff[entry] == NULL) { /* allocate sk_buff for this free entry in ring */ skb = netdev_alloc_skb(bp->dev, bp->rx_buffer_size); @@ -698,7 +689,6 @@ static int gem_rx(struct macb *bp, int budget) if (!(addr & MACB_BIT(RX_USED))) break; - desc->addr &= ~MACB_BIT(RX_USED); bp->rx_tail++; count++; |