tg3: Prevent page allocation failure during TSO workaround

If any TSO fragment hits hardware bug conditions (e.g. 4G boundary), the
driver will workaround by calling skb_copy() to copy to a linear SKB.  Users
have reported page allocation failures as the TSO packet can be up to 64K.
Copying such a large packet is also very inefficient.  We fix this by using
existing tg3_tso_bug() to transmit the packet using GSO.

Signed-off-by: Prashant Sreedharan <prashant@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 7 deletions

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index bdfd08bcfe57..36b2b51facb9 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -7882,6 +7882,10 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
         struct tg3_napi *tnapi;
         struct netdev_queue *txq;
         unsigned int last;
+        struct iphdr *iph = NULL;
+        struct tcphdr *tcph = NULL;
+        __sum16 tcp_csum = 0, ip_csum = 0;
+        __be16 ip_tot_len = 0;
 
         txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
         tnapi = &tp->napi[skb_get_queue_mapping(skb)];
@@ -7913,7 +7917,6 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
         mss = skb_shinfo(skb)->gso_size;
         if (mss) {
-                struct iphdr *iph;
                 u32 tcp_opt_len, hdr_len;
 
                 if (skb_cow_head(skb, 0))
@@ -7929,6 +7932,8 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
                             tg3_flag(tp, TSO_BUG))
                                 return tg3_tso_bug(tp, skb);
 
+                        ip_csum = iph->check;
+                        ip_tot_len = iph->tot_len;
                         iph->check = 0;
                         iph->tot_len = htons(mss + hdr_len);
                 }
@@ -7936,16 +7941,18 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
                 base_flags |= (TXD_FLAG_CPU_PRE_DMA |
                                TXD_FLAG_CPU_POST_DMA);
 
+                tcph = tcp_hdr(skb);
+                tcp_csum = tcph->check;
+
                 if (tg3_flag(tp, HW_TSO_1) ||
                     tg3_flag(tp, HW_TSO_2) ||
                     tg3_flag(tp, HW_TSO_3)) {
-                        tcp_hdr(skb)->check = 0;
+                        tcph->check = 0;
                         base_flags &= ~TXD_FLAG_TCPUDP_CSUM;
-                } else
-                        tcp_hdr(skb)->check = ~csum_tcpudp_magic(iph->saddr,
-                                                                 iph->daddr, 0,
-                                                                 IPPROTO_TCP,
-                                                                 0);
+                } else {
+                        tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
+                                                         0, IPPROTO_TCP, 0);
+                }
 
                 if (tg3_flag(tp, HW_TSO_3)) {
                         mss |= (hdr_len & 0xc) << 12;
@@ -8045,6 +8052,18 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
         if (would_hit_hwbug) {
                 tg3_tx_skb_unmap(tnapi, tnapi->tx_prod, i);
 
+                if (mss) {
+                        /* If it's a TSO packet, do GSO instead of
+                         * allocating and copying to a large linear SKB
+                         */
+                        if (ip_tot_len) {
+                                iph->check = ip_csum;
+                                iph->tot_len = ip_tot_len;
+                        }
+                        tcph->check = tcp_csum;
+                        return tg3_tso_bug(tp, skb);
+                }
+
                 /* If the workaround fails due to memory/mapping
                  * failure, silently drop this packet.
                  */