pasemi_mac: Fix TX ring wrap checking
The old logic didn't detect full (tx) ring cases properly, causing
overruns and general badness. Clean it up a bit and abstract out the
ring size checks, always making sure to leave 1 slot open.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/pasemi_mac.c b/drivers/net/pasemi_mac.c
index 4836d40..dc710a0 100644
--- a/drivers/net/pasemi_mac.c
+++ b/drivers/net/pasemi_mac.c
@@ -69,6 +69,10 @@
#define RX_DESC_INFO(mac, num) ((mac)->rx->desc_info[(num) & (RX_RING_SIZE-1)])
#define RX_BUFF(mac, num) ((mac)->rx->buffers[(num) & (RX_RING_SIZE-1)])
+#define RING_USED(ring) (((ring)->next_to_fill - (ring)->next_to_clean) \
+ & ((ring)->size - 1))
+#define RING_AVAIL(ring) ((ring->size) - RING_USED(ring))
+
#define BUF_SIZE 1646 /* 1500 MTU + ETH_HLEN + VLAN_HLEN + 2 64B cachelines */
MODULE_LICENSE("GPL");
@@ -174,6 +178,7 @@
spin_lock_init(&ring->lock);
+ ring->size = RX_RING_SIZE;
ring->desc_info = kzalloc(sizeof(struct pasemi_mac_buffer) *
RX_RING_SIZE, GFP_KERNEL);
@@ -253,6 +258,7 @@
spin_lock_init(&ring->lock);
+ ring->size = TX_RING_SIZE;
ring->desc_info = kzalloc(sizeof(struct pasemi_mac_buffer) *
TX_RING_SIZE, GFP_KERNEL);
if (!ring->desc_info)
@@ -281,7 +287,7 @@
PAS_DMA_TXCHAN_CFG_UP |
PAS_DMA_TXCHAN_CFG_WT(2));
- ring->next_to_use = 0;
+ ring->next_to_fill = 0;
ring->next_to_clean = 0;
snprintf(ring->irq_name, sizeof(ring->irq_name),
@@ -376,9 +382,7 @@
int start = mac->rx->next_to_fill;
unsigned int limit, count;
- limit = (mac->rx->next_to_clean + RX_RING_SIZE -
- mac->rx->next_to_fill) & (RX_RING_SIZE - 1);
-
+ limit = RING_AVAIL(mac->rx);
/* Check to see if we're doing first-time setup */
if (unlikely(mac->rx->next_to_clean == 0 && mac->rx->next_to_fill == 0))
limit = RX_RING_SIZE;
@@ -562,7 +566,7 @@
spin_lock_irqsave(&mac->tx->lock, flags);
start = mac->tx->next_to_clean;
- limit = min(mac->tx->next_to_use, start+32);
+ limit = min(mac->tx->next_to_fill, start+32);
count = 0;
@@ -1004,14 +1008,13 @@
spin_lock_irqsave(&txring->lock, flags);
- if (txring->next_to_clean - txring->next_to_use == TX_RING_SIZE) {
+ if (RING_AVAIL(txring) <= 1) {
spin_unlock_irqrestore(&txring->lock, flags);
pasemi_mac_clean_tx(mac);
pasemi_mac_restart_tx_intr(mac);
spin_lock_irqsave(&txring->lock, flags);
- if (txring->next_to_clean - txring->next_to_use ==
- TX_RING_SIZE) {
+ if (RING_AVAIL(txring) <= 1) {
/* Still no room -- stop the queue and wait for tx
* intr when there's room.
*/
@@ -1020,15 +1023,15 @@
}
}
- dp = &TX_DESC(mac, txring->next_to_use);
- info = &TX_DESC_INFO(mac, txring->next_to_use);
+ dp = &TX_DESC(mac, txring->next_to_fill);
+ info = &TX_DESC_INFO(mac, txring->next_to_fill);
dp->mactx = mactx;
dp->ptr = ptr;
info->dma = map;
info->skb = skb;
- txring->next_to_use++;
+ txring->next_to_fill++;
mac->stats.tx_packets++;
mac->stats.tx_bytes += skb->len;