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Commit 52c0fd83 authored by Michael Chan's avatar Michael Chan Committed by David S. Miller
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[TG3]: Add TSO workaround using GSO 



Use GSO to workaround a rare TSO bug on some chips.  This hardware
bug may be triggered when the TSO header size is greater than 80
bytes.  When this condition is detected in a TSO packet, the driver
will use GSO to segment the packet to workaround the hardware bug.

Thanks to Juergen Kreileder <jk@blackdown.de> for reporting the
problem and collecting traces to help debug the problem.

And thanks to Herbert Xu <herbert@gondor.apana.org.au> for providing
the GSO mechanism that happens to be the perfect workaround for this
problem.

Signed-off-by: default avatarMichael Chan <mchan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1661394e

drivers/net/tg3.c

+49 −4
Original line number Diff line number Diff line
@@ -3880,6 +3880,40 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev) 
	return NETDEV_TX_OK;

}



#if TG3_TSO_SUPPORT != 0

static int tg3_start_xmit_dma_bug(struct sk_buff *, struct net_device *);



/* Use GSO to workaround a rare TSO bug that may be triggered when the

 * TSO header is greater than 80 bytes.

 */

static int tg3_tso_bug(struct tg3 *tp, struct sk_buff *skb)

{

	struct sk_buff *segs, *nskb;



	/* Estimate the number of fragments in the worst case */

	if (unlikely(TX_BUFFS_AVAIL(tp) <= (skb_shinfo(skb)->gso_segs * 3))) {

		netif_stop_queue(tp->dev);

		return NETDEV_TX_BUSY;

	}



	segs = skb_gso_segment(skb, tp->dev->features & ~NETIF_F_TSO);

	if (unlikely(IS_ERR(segs)))

		goto tg3_tso_bug_end;



	do {

		nskb = segs;

		segs = segs->next;

		nskb->next = NULL;

		tg3_start_xmit_dma_bug(nskb, tp->dev);

	} while (segs);



tg3_tso_bug_end:

	dev_kfree_skb(skb);



	return NETDEV_TX_OK;

}

#endif



/* hard_start_xmit for devices that have the 4G bug and/or 40-bit bug and

 * support TG3_FLG2_HW_TSO_1 or firmware TSO only.

 */
@@ -3916,7 +3950,7 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev) 
	mss = 0;

	if (skb->len > (tp->dev->mtu + ETH_HLEN) &&

	    (mss = skb_shinfo(skb)->gso_size) != 0) {

		int tcp_opt_len, ip_tcp_len;

		int tcp_opt_len, ip_tcp_len, hdr_len;



		if (skb_header_cloned(skb) &&

		    pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
@@ -3927,11 +3961,16 @@ static int tg3_start_xmit_dma_bug(struct sk_buff *skb, struct net_device *dev) 
		tcp_opt_len = ((skb->h.th->doff - 5) * 4);

		ip_tcp_len = (skb->nh.iph->ihl * 4) + sizeof(struct tcphdr);



		hdr_len = ip_tcp_len + tcp_opt_len;

		if (unlikely((ETH_HLEN + hdr_len) > 80) &&

			     (tp->tg3_flags2 & TG3_FLG2_HW_TSO_1_BUG))

			return (tg3_tso_bug(tp, skb));



		base_flags |= (TXD_FLAG_CPU_PRE_DMA |

			       TXD_FLAG_CPU_POST_DMA);



		skb->nh.iph->check = 0;

		skb->nh.iph->tot_len = htons(mss + ip_tcp_len + tcp_opt_len);

		skb->nh.iph->tot_len = htons(mss + hdr_len);

		if (tp->tg3_flags2 & TG3_FLG2_HW_TSO) {

			skb->h.th->check = 0;

			base_flags &= ~TXD_FLAG_TCPUDP_CSUM;
@@ -10192,8 +10231,14 @@ static int __devinit tg3_get_invariants(struct tg3 *tp) 
		    GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5787) {

			tp->tg3_flags2 |= TG3_FLG2_HW_TSO_2;

			tp->tg3_flags2 |= TG3_FLG2_1SHOT_MSI;

		} else

			tp->tg3_flags2 |= TG3_FLG2_HW_TSO_1;

		} else {

			tp->tg3_flags2 |= TG3_FLG2_HW_TSO_1 |

					  TG3_FLG2_HW_TSO_1_BUG;

			if (GET_ASIC_REV(tp->pci_chip_rev_id) ==

				ASIC_REV_5750 &&

	     		    tp->pci_chip_rev_id >= CHIPREV_ID_5750_C2)

				tp->tg3_flags2 &= ~TG3_FLG2_HW_TSO_1_BUG;

		}

	}



	if (GET_ASIC_REV(tp->pci_chip_rev_id) != ASIC_REV_5705 &&

drivers/net/tg3.h

+2 −1
Original line number Diff line number Diff line
@@ -125,6 +125,7 @@ 
#define  CHIPREV_ID_5750_A0		 0x4000

#define  CHIPREV_ID_5750_A1		 0x4001

#define  CHIPREV_ID_5750_A3		 0x4003

#define  CHIPREV_ID_5750_C2		 0x4202

#define  CHIPREV_ID_5752_A0_HW		 0x5000

#define  CHIPREV_ID_5752_A0		 0x6000

#define  CHIPREV_ID_5752_A1		 0x6001
@@ -2193,7 +2194,7 @@ struct tg3 { 
#define TG3_FLAG_INIT_COMPLETE		0x80000000

	u32				tg3_flags2;

#define TG3_FLG2_RESTART_TIMER		0x00000001

/*					0x00000002 available */

#define TG3_FLG2_HW_TSO_1_BUG		0x00000002

#define TG3_FLG2_NO_ETH_WIRE_SPEED	0x00000004

#define TG3_FLG2_IS_5788		0x00000008

#define TG3_FLG2_MAX_RXPEND_64		0x00000010