[PATCH] S2io: NAPI fix

1. When processing Rx packets, making sure that get offset of ring
does not cross the put offset.

2. when NAPI is not in use a new spinlock(put_lock) is used to make
sure accessing put offset of ring is atomic.

3. Also introduced a new vaiable put_pos in nic_t to keep track of
absolute position of the put pointer of Rx ring.

4. When NAPI is used, fill_rx_buffer is not called from the interrupt
handler(s2io_isr) .

5. In s2io_poll, decrementing packets processed is done inside the
while loop unlike out side it as was being done last time.
Signed-off-by: Raghavendra Koushik <raghavendra.koushik@s2io.com>
Signed-off-by: Ravinandan Arakali <ravinandan.arakali@s2io.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/net/s2io.c

@@ -1565,6 +1565,9 @@ int fill_rx_buffers(struct s2io_nic *nic, int ring_no)
 	    atomic_read(&nic->rx_bufs_left[ring_no]);
 	mac_info_t *mac_control;
 	struct config_param *config;
+#ifndef CONFIG_S2IO_NAPI
+	unsigned long flags;
+#endif
 
 	mac_control = &nic->mac_control;
 	config = &nic->config;
@@ -1612,6 +1615,12 @@ int fill_rx_buffers(struct s2io_nic *nic, int ring_no)
 			DBG_PRINT(INTR_DBG, "%s: Next block at: %p\n",
 				  dev->name, rxdp);
 		}
+#ifndef CONFIG_S2IO_NAPI
+		spin_lock_irqsave(&nic->put_lock, flags);
+		nic->put_pos[ring_no] = (block_no *
+					 (MAX_RXDS_PER_BLOCK + 1)) + off;
+		spin_unlock_irqrestore(&nic->put_lock, flags);
+#endif
 
 		if (rxdp->Control_1 & RXD_OWN_XENA) {
 			mac_control->rx_curr_put_info[ring_no].
@@ -1730,8 +1739,8 @@ static int s2io_poll(struct net_device *dev, int *budget)
 	XENA_dev_config_t *bar0 = (XENA_dev_config_t *) nic->bar0;
 	int pkts_to_process = *budget, pkt_cnt = 0;
 	register u64 val64 = 0;
-	rx_curr_get_info_t offset_info;
-	int i, block_no;
+	rx_curr_get_info_t get_info, put_info;
+	int i, get_block, put_block, get_offset, put_offset, ring_bufs;
 	u16 val16, cksum;
 	struct sk_buff *skb;
 	RxD_t *rxdp;
@@ -1748,29 +1757,40 @@ static int s2io_poll(struct net_device *dev, int *budget)
 	writeq(val64, &bar0->rx_traffic_int);
 
 	for (i = 0; i < config->rx_ring_num; i++) {
-		if (--pkts_to_process < 0) {
-			goto no_rx;
-		}
-		offset_info = mac_control->rx_curr_get_info[i];
-		block_no = offset_info.block_index;
-		rxdp = nic->rx_blocks[i][block_no].block_virt_addr +
-		    offset_info.offset;
-		while (!(rxdp->Control_1 & RXD_OWN_XENA)) {
+		get_info = mac_control->rx_curr_get_info[i];
+		get_block = get_info.block_index;
+		put_info = mac_control->rx_curr_put_info[i];
+		put_block = put_info.block_index;
+		ring_bufs = config->rx_cfg[i].num_rxd;
+		rxdp = nic->rx_blocks[i][get_block].block_virt_addr +
+		    get_info.offset;
+		get_offset = (get_block * (MAX_RXDS_PER_BLOCK + 1)) +
+		    get_info.offset;
+		put_offset = (put_block * (MAX_RXDS_PER_BLOCK + 1)) +
+		    put_info.offset;
+		while ((!(rxdp->Control_1 & RXD_OWN_XENA)) &&
+		       (((get_offset + 1) % ring_bufs) != put_offset)) {
+			if (--pkts_to_process < 0) {
+				goto no_rx;
+			}
 			if (rxdp->Control_1 == END_OF_BLOCK) {
 				rxdp =
 				    (RxD_t *) ((unsigned long) rxdp->
 					       Control_2);
-				offset_info.offset++;
-				offset_info.offset %=
+				get_info.offset++;
+				get_info.offset %=
 				    (MAX_RXDS_PER_BLOCK + 1);
-				block_no++;
-				block_no %= nic->block_count[i];
+				get_block++;
+				get_block %= nic->block_count[i];
 				mac_control->rx_curr_get_info[i].
-				    offset = offset_info.offset;
+				    offset = get_info.offset;
 				mac_control->rx_curr_get_info[i].
-				    block_index = block_no;
+				    block_index = get_block;
 				continue;
 			}
+			get_offset =
+			    (get_block * (MAX_RXDS_PER_BLOCK + 1)) +
+			    get_info.offset;
 			skb =
 			    (struct sk_buff *) ((unsigned long) rxdp->
 						Host_Control);
@@ -1778,7 +1798,7 @@ static int s2io_poll(struct net_device *dev, int *budget)
 				DBG_PRINT(ERR_DBG, "%s: The skb is ",
 					  dev->name);
 				DBG_PRINT(ERR_DBG, "Null in Rx Intr\n");
-				return 0;
+				goto no_rx;
 			}
 			val64 = RXD_GET_BUFFER0_SIZE(rxdp->Control_2);
 			val16 = (u16) (val64 >> 48);
@@ -1792,34 +1812,44 @@ static int s2io_poll(struct net_device *dev, int *budget)
 					 PCI_DMA_FROMDEVICE);
 			rx_osm_handler(nic, val16, rxdp, i);
 			pkt_cnt++;
-			offset_info.offset++;
-			offset_info.offset %= (MAX_RXDS_PER_BLOCK + 1);
+			get_info.offset++;
+			get_info.offset %= (MAX_RXDS_PER_BLOCK + 1);
 			rxdp =
-			    nic->rx_blocks[i][block_no].block_virt_addr +
-			    offset_info.offset;
+			    nic->rx_blocks[i][get_block].block_virt_addr +
+			    get_info.offset;
 			mac_control->rx_curr_get_info[i].offset =
-			    offset_info.offset;
+			    get_info.offset;
 		}
 	}
 	if (!pkt_cnt)
 		pkt_cnt = 1;
 
-	for (i = 0; i < config->rx_ring_num; i++)
-		fill_rx_buffers(nic, i);
-
 	dev->quota -= pkt_cnt;
 	*budget -= pkt_cnt;
 	netif_rx_complete(dev);
 
+	for (i = 0; i < config->rx_ring_num; i++) {
+		if (fill_rx_buffers(nic, i) == -ENOMEM) {
+			DBG_PRINT(ERR_DBG, "%s:Out of memory", dev->name);
+			DBG_PRINT(ERR_DBG, " in Rx Poll!!\n");
+			break;
+		}
+	}
 	/* Re enable the Rx interrupts. */
 	en_dis_able_nic_intrs(nic, RX_TRAFFIC_INTR, ENABLE_INTRS);
 	return 0;
 
       no_rx:
-	for (i = 0; i < config->rx_ring_num; i++)
-		fill_rx_buffers(nic, i);
 	dev->quota -= pkt_cnt;
 	*budget -= pkt_cnt;
+
+	for (i = 0; i < config->rx_ring_num; i++) {
+		if (fill_rx_buffers(nic, i) == -ENOMEM) {
+			DBG_PRINT(ERR_DBG, "%s:Out of memory", dev->name);
+			DBG_PRINT(ERR_DBG, " in Rx Poll!!\n");
+			break;
+		}
+	}
 	return 1;
 }
 #else
@@ -1840,12 +1870,13 @@ static void rx_intr_handler(struct s2io_nic *nic)
 {
 	struct net_device *dev = (struct net_device *) nic->dev;
 	XENA_dev_config_t *bar0 = (XENA_dev_config_t *) nic->bar0;
-	rx_curr_get_info_t offset_info;
+	rx_curr_get_info_t get_info, put_info;
 	RxD_t *rxdp;
 	struct sk_buff *skb;
 	u16 val16, cksum;
 	register u64 val64 = 0;
-	int i, block_no, pkt_cnt = 0;
+	int get_block, get_offset, put_block, put_offset, ring_bufs;
+	int i, pkt_cnt = 0;
 	mac_info_t *mac_control;
 	struct config_param *config;
 
@@ -1860,25 +1891,37 @@ static void rx_intr_handler(struct s2io_nic *nic)
 	writeq(val64, &bar0->rx_traffic_int);
 
 	for (i = 0; i < config->rx_ring_num; i++) {
-		offset_info = mac_control->rx_curr_get_info[i];
-		block_no = offset_info.block_index;
-		rxdp = nic->rx_blocks[i][block_no].block_virt_addr +
-		    offset_info.offset;
-		while (!(rxdp->Control_1 & RXD_OWN_XENA)) {
+		get_info = mac_control->rx_curr_get_info[i];
+		get_block = get_info.block_index;
+		put_info = mac_control->rx_curr_put_info[i];
+		put_block = put_info.block_index;
+		ring_bufs = config->rx_cfg[i].num_rxd;
+		rxdp = nic->rx_blocks[i][get_block].block_virt_addr +
+		    get_info.offset;
+		get_offset = (get_block * (MAX_RXDS_PER_BLOCK + 1)) +
+		    get_info.offset;
+		spin_lock(&nic->put_lock);
+		put_offset = nic->put_pos[i];
+		spin_unlock(&nic->put_lock);
+		while ((!(rxdp->Control_1 & RXD_OWN_XENA)) &&
+		       (((get_offset + 1) % ring_bufs) != put_offset)) {
 			if (rxdp->Control_1 == END_OF_BLOCK) {
 				rxdp = (RxD_t *) ((unsigned long)
 						  rxdp->Control_2);
-				offset_info.offset++;
-				offset_info.offset %=
+				get_info.offset++;
+				get_info.offset %=
 				    (MAX_RXDS_PER_BLOCK + 1);
-				block_no++;
-				block_no %= nic->block_count[i];
+				get_block++;
+				get_block %= nic->block_count[i];
 				mac_control->rx_curr_get_info[i].
-				    offset = offset_info.offset;
+				    offset = get_info.offset;
 				mac_control->rx_curr_get_info[i].
-				    block_index = block_no;
+				    block_index = get_block;
 				continue;
 			}
+			get_offset =
+			    (get_block * (MAX_RXDS_PER_BLOCK + 1)) +
+			    get_info.offset;
 			skb = (struct sk_buff *) ((unsigned long)
 						  rxdp->Host_Control);
 			if (skb == NULL) {
@@ -1898,13 +1941,13 @@ static void rx_intr_handler(struct s2io_nic *nic)
 					 HEADER_SNAP_SIZE,
 					 PCI_DMA_FROMDEVICE);
 			rx_osm_handler(nic, val16, rxdp, i);
-			offset_info.offset++;
-			offset_info.offset %= (MAX_RXDS_PER_BLOCK + 1);
+			get_info.offset++;
+			get_info.offset %= (MAX_RXDS_PER_BLOCK + 1);
 			rxdp =
-			    nic->rx_blocks[i][block_no].block_virt_addr +
-			    offset_info.offset;
+			    nic->rx_blocks[i][get_block].block_virt_addr +
+			    get_info.offset;
 			mac_control->rx_curr_get_info[i].offset =
-			    offset_info.offset;
+			    get_info.offset;
 			pkt_cnt++;
 			if ((indicate_max_pkts)
 			    && (pkt_cnt > indicate_max_pkts))
@@ -2575,6 +2618,9 @@ static irqreturn_t s2io_isr(int irq, void *dev_id, struct pt_regs *regs)
 	struct net_device *dev = (struct net_device *) dev_id;
 	nic_t *sp = dev->priv;
 	XENA_dev_config_t *bar0 = (XENA_dev_config_t *) sp->bar0;
+#ifndef CONFIG_S2IO_NAPI
+	int i, ret;
+#endif
 	u64 reason = 0;
 	mac_info_t *mac_control;
 	struct config_param *config;
@@ -2626,44 +2672,31 @@ static irqreturn_t s2io_isr(int irq, void *dev_id, struct pt_regs *regs)
 	 * reallocate the buffers from the interrupt handler itself, 
 	 * else schedule a tasklet to reallocate the buffers.
 	 */
-#if 1
-	{
-		int i;
-
-		for (i = 0; i < config->rx_ring_num; i++) {
-			int rxb_size = atomic_read(&sp->rx_bufs_left[i]);
-			int level = rx_buffer_level(sp, rxb_size, i);
-
-			if ((level == PANIC) && (!TASKLET_IN_USE)) {
-				int ret;
-
-				DBG_PRINT(INTR_DBG, "%s: Rx BD hit ",
+#ifndef CONFIG_S2IO_NAPI
+	for (i = 0; i < config->rx_ring_num; i++) {
+		int rxb_size = atomic_read(&sp->rx_bufs_left[i]);
+		int level = rx_buffer_level(sp, rxb_size, i);
+
+		if ((level == PANIC) && (!TASKLET_IN_USE)) {
+			DBG_PRINT(INTR_DBG, "%s: Rx BD hit ", dev->name);
+			DBG_PRINT(INTR_DBG, "PANIC levels\n");
+			if ((ret = fill_rx_buffers(sp, i)) == -ENOMEM) {
+				DBG_PRINT(ERR_DBG, "%s:Out of memory",
 					  dev->name);
-				DBG_PRINT(INTR_DBG, "PANIC levels\n");
-				if ((ret =
-				     fill_rx_buffers(sp, i)) == -ENOMEM) {
-					DBG_PRINT(ERR_DBG,
-						  "%s:Out of memory",
-						  dev->name);
-					DBG_PRINT(ERR_DBG, " in ISR!!\n");
-					clear_bit(0,
-						  (unsigned long *) (&sp->
-								     tasklet_status));
-					return IRQ_HANDLED;
-				}
+				DBG_PRINT(ERR_DBG, " in ISR!!\n");
 				clear_bit(0,
 					  (unsigned long *) (&sp->
 							     tasklet_status));
-			} else if ((level == LOW)
-				   && (!atomic_read(&sp->tasklet_status))) {
-				tasklet_schedule(&sp->task);
+				return IRQ_HANDLED;
 			}
-
+			clear_bit(0,
+				  (unsigned long *) (&sp->tasklet_status));
+		} else if ((level == LOW)
+			   && (!atomic_read(&sp->tasklet_status))) {
+			tasklet_schedule(&sp->task);
 		}
 
 	}
-#else
-	tasklet_schedule(&sp->task);
 #endif
 
 	return IRQ_HANDLED;
@@ -4575,6 +4608,9 @@ s2io_init_nic(struct pci_dev *pdev, const struct pci_device_id *pre)
 
 	/* Initialize spinlocks */
 	spin_lock_init(&sp->tx_lock);
+#ifndef CONFIG_S2IO_NAPI
+	spin_lock_init(&sp->put_lock);
+#endif
 
 	/* 
 	 * SXE-002: Configure link and activity LED to init state 

drivers/net/s2io.h

@@ -610,6 +610,9 @@ typedef struct s2io_nic {
 	atomic_t rx_bufs_left[MAX_RX_RINGS];
 
 	spinlock_t tx_lock;
+#ifndef CONFIG_S2IO_NAPI
+	spinlock_t put_lock;
+#endif
 
 #define PROMISC     1
 #define ALL_MULTI   2
@@ -628,6 +631,11 @@ typedef struct s2io_nic {
 	u16 tx_err_count;
 	u16 rx_err_count;
 
+#ifndef CONFIG_S2IO_NAPI
+	/* Index to the absolute position of the put pointer of Rx ring. */
+	int put_pos[MAX_RX_RINGS];
+#endif
+
 	/*
 	 *  Place holders for the virtual and physical addresses of 
 	 *  all the Rx Blocks