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Commit c58ec932 authored by Michael Chan's avatar Michael Chan Committed by David S. Miller
Browse files

[TG3]: Fix 4GB boundary tx handling 



Fix and simplify the workaround code for the 4GB boundary tx buffer
hardware bug.

1. Need to unmap the original SKB's dma addresses if a new SKB cannot
   be allocated.

2. Need to pass the base flag to tigon3_4gb_hwbug_workaround() or TSO
   won't work properly.

3. The guilty entry and length parameters for
   tigon3_4gb_hwbug_workaround() are removed as they are not necessary.

4. Remove assumption that only one fragment can hit the 4GB boundary.
   Another fragment can hit 8GB for example.

Signed-off-by: default avatarMichael Chan <mchan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent eb8edb08

drivers/net/tg3.c

+39 −55
Original line number Diff line number Diff line
@@ -3442,30 +3442,46 @@ static void tg3_tx_timeout(struct net_device *dev) 
	schedule_work(&tp->reset_task);

}



/* Test for DMA buffers crossing any 4GB boundaries: 4G, 8G, etc */

static inline int tg3_4g_overflow_test(dma_addr_t mapping, int len)

{

	u32 base = (u32) mapping & 0xffffffff;



	return ((base > 0xffffdcc0) &&

		(base + len + 8 < base));

}



static void tg3_set_txd(struct tg3 *, int, dma_addr_t, int, u32, u32);



static int tigon3_4gb_hwbug_workaround(struct tg3 *tp, struct sk_buff *skb,

				       u32 guilty_entry, int guilty_len,

				       u32 last_plus_one, u32 *start, u32 mss)

				       u32 last_plus_one, u32 *start,

				       u32 base_flags, u32 mss)

{

	struct sk_buff *new_skb = skb_copy(skb, GFP_ATOMIC);

	dma_addr_t new_addr;

	dma_addr_t new_addr = 0;

	u32 entry = *start;

	int i;

	int i, ret = 0;



	if (!new_skb) {

		dev_kfree_skb(skb);

		return -1;

	}



		ret = -1;

	} else {

		/* New SKB is guaranteed to be linear. */

		entry = *start;

		new_addr = pci_map_single(tp->pdev, new_skb->data, new_skb->len,

					  PCI_DMA_TODEVICE);

		/* Make sure new skb does not cross any 4G boundaries.

		 * Drop the packet if it does.

		 */

		if (tg3_4g_overflow_test(new_addr, new_skb->len)) {

			ret = -1;

			dev_kfree_skb(new_skb);

			new_skb = NULL;

		} else {

			tg3_set_txd(tp, entry, new_addr, new_skb->len,

		    (skb->ip_summed == CHECKSUM_HW) ?

		    TXD_FLAG_TCPUDP_CSUM : 0, 1 | (mss << 1));

				    base_flags, 1 | (mss << 1));

			*start = NEXT_TX(entry);

		}

	}



	/* Now clean up the sw ring entries. */

	i = 0;
@@ -3491,7 +3507,7 @@ static int tigon3_4gb_hwbug_workaround(struct tg3 *tp, struct sk_buff *skb, 


	dev_kfree_skb(skb);



	return 0;

	return ret;

}



static void tg3_set_txd(struct tg3 *tp, int entry,
@@ -3517,19 +3533,10 @@ static void tg3_set_txd(struct tg3 *tp, int entry, 
	txd->vlan_tag = vlan_tag << TXD_VLAN_TAG_SHIFT;

}



static inline int tg3_4g_overflow_test(dma_addr_t mapping, int len)

{

	u32 base = (u32) mapping & 0xffffffff;



	return ((base > 0xffffdcc0) &&

		(base + len + 8 < base));

}



static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)

{

	struct tg3 *tp = netdev_priv(dev);

	dma_addr_t mapping;

	unsigned int i;

	u32 len, entry, base_flags, mss;

	int would_hit_hwbug;
@@ -3624,7 +3631,7 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev) 
	would_hit_hwbug = 0;



	if (tg3_4g_overflow_test(mapping, len))

		would_hit_hwbug = entry + 1;

		would_hit_hwbug = 1;



	tg3_set_txd(tp, entry, mapping, len, base_flags,

		    (skb_shinfo(skb)->nr_frags == 0) | (mss << 1));
@@ -3648,12 +3655,8 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev) 
			tp->tx_buffers[entry].skb = NULL;

			pci_unmap_addr_set(&tp->tx_buffers[entry], mapping, mapping);



			if (tg3_4g_overflow_test(mapping, len)) {

				/* Only one should match. */

				if (would_hit_hwbug)

					BUG();

				would_hit_hwbug = entry + 1;

			}

			if (tg3_4g_overflow_test(mapping, len))

				would_hit_hwbug = 1;



			if (tp->tg3_flags2 & TG3_FLG2_HW_TSO)

				tg3_set_txd(tp, entry, mapping, len,
@@ -3669,34 +3672,15 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev) 
	if (would_hit_hwbug) {

		u32 last_plus_one = entry;

		u32 start;

		unsigned int len = 0;



		would_hit_hwbug -= 1;

		entry = entry - 1 - skb_shinfo(skb)->nr_frags;

		entry &= (TG3_TX_RING_SIZE - 1);

		start = entry;

		i = 0;

		while (entry != last_plus_one) {

			if (i == 0)

				len = skb_headlen(skb);

			else

				len = skb_shinfo(skb)->frags[i-1].size;



			if (entry == would_hit_hwbug)

				break;



			i++;

			entry = NEXT_TX(entry);



		}

		start = entry - 1 - skb_shinfo(skb)->nr_frags;

		start &= (TG3_TX_RING_SIZE - 1);



		/* If the workaround fails due to memory/mapping

		 * failure, silently drop this packet.

		 */

		if (tigon3_4gb_hwbug_workaround(tp, skb,

						entry, len,

						last_plus_one,

						&start, mss))

		if (tigon3_4gb_hwbug_workaround(tp, skb, last_plus_one,

						&start, base_flags, mss))

			goto out_unlock;



		entry = start;