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net: better IFF_XMIT_DST_RELEASE support

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Testing xmit_more support with netperf and connected UDP sockets,
I found strange dst refcount false sharing.

Current handling of IFF_XMIT_DST_RELEASE is not optimal.

Dropping dst in validate_xmit_skb() is certainly too late in case
packet was queued by cpu X but dequeued by cpu Y

The logical point to take care of drop/force is in __dev_queue_xmit()
before even taking qdisc lock.

As Julian Anastasov pointed out, need for skb_dst() might come from some
packet schedulers or classifiers.

This patch adds new helper to cleanly express needs of various drivers
or qdiscs/classifiers.

Drivers that need skb_dst() in their ndo_start_xmit() should call
following helper in their setup instead of the prior :

	dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
->
	netif_keep_dst(dev);

Instead of using a single bit, we use two bits, one being
eventually rebuilt in bonding/team drivers.

The other one, is permanent and blocks IFF_XMIT_DST_RELEASE being
rebuilt in bonding/team. Eventually, we could add something
smarter later.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-10-05 18:38:35 -07:00 committed by David S. Miller
parent fe971b95c2
commit 0287587884
27 changed files with 54 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/infiniband/ulp/ipoib/ipoib_main.c
View File

@ -1364,7 +1364,7 @@ void ipoib_setup(struct net_device *dev)
dev->tx_queue_len = ipoib_sendq_size * 2;
dev->features = (NETIF_F_VLAN_CHALLENGED |
NETIF_F_HIGHDMA);
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
memcpy(dev->broadcast, ipv4_bcast_addr, INFINIBAND_ALEN);

2
drivers/net/appletalk/ipddp.c
View File

@ -74,7 +74,7 @@ static struct net_device * __init ipddp_init(void)
if (!dev)
return ERR_PTR(-ENOMEM);
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
strcpy(dev->name, "ipddp%d");
if (version_printed++ == 0)

9
drivers/net/bonding/bond_main.c
View File

@ -1002,7 +1002,8 @@ static netdev_features_t bond_fix_features(struct net_device *dev,
static void bond_compute_features(struct bonding *bond)
{
unsigned int flags, dst_release_flag = IFF_XMIT_DST_RELEASE;
unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE |
IFF_XMIT_DST_RELEASE_PERM;
netdev_features_t vlan_features = BOND_VLAN_FEATURES;
netdev_features_t enc_features = BOND_ENC_FEATURES;
struct net_device *bond_dev = bond->dev;
@ -1038,8 +1039,10 @@ done:
bond_dev->gso_max_segs = gso_max_segs;
netif_set_gso_max_size(bond_dev, gso_max_size);
flags = bond_dev->priv_flags & ~IFF_XMIT_DST_RELEASE;
bond_dev->priv_flags = flags | dst_release_flag;
bond_dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
if ((bond_dev->priv_flags & IFF_XMIT_DST_RELEASE_PERM) &&
dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM))
bond_dev->priv_flags |= IFF_XMIT_DST_RELEASE;
netdev_change_features(bond_dev);
}

2
drivers/net/eql.c
View File

@ -199,7 +199,7 @@ static void __init eql_setup(struct net_device *dev)
dev->type = ARPHRD_SLIP;
dev->tx_queue_len = 5; /* Hands them off fast */
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
}
static int eql_open(struct net_device *dev)

3
drivers/net/ifb.c
View File

@ -185,7 +185,8 @@ static void ifb_setup(struct net_device *dev)
dev->flags |= IFF_NOARP;
dev->flags &= ~IFF_MULTICAST;
dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
dev->priv_flags &= ~IFF_TX_SKB_SHARING;
netif_keep_dst(dev);
eth_hw_addr_random(dev);
}

2
drivers/net/loopback.c
View File

@ -169,7 +169,7 @@ static void loopback_setup(struct net_device *dev)
dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
dev->flags = IFF_LOOPBACK;
dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
dev->hw_features = NETIF_F_ALL_TSO | NETIF_F_UFO;
dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
| NETIF_F_ALL_TSO

3
drivers/net/macvlan.c
View File

@ -1025,7 +1025,8 @@ void macvlan_common_setup(struct net_device *dev)
{
ether_setup(dev);
dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
dev->priv_flags &= ~IFF_TX_SKB_SHARING;
netif_keep_dst(dev);
dev->priv_flags |= IFF_UNICAST_FLT;
dev->netdev_ops = &macvlan_netdev_ops;
dev->destructor = free_netdev;

2
drivers/net/ppp/ppp_generic.c
View File

@ -1103,7 +1103,7 @@ static void ppp_setup(struct net_device *dev)
dev->type = ARPHRD_PPP;
dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
dev->features |= NETIF_F_NETNS_LOCAL;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
}
/*

8
drivers/net/team/team.c
View File

@ -970,7 +970,8 @@ static void __team_compute_features(struct team *team)
struct team_port *port;
u32 vlan_features = TEAM_VLAN_FEATURES & NETIF_F_ALL_FOR_ALL;
unsigned short max_hard_header_len = ETH_HLEN;
unsigned int flags, dst_release_flag = IFF_XMIT_DST_RELEASE;
unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE |
IFF_XMIT_DST_RELEASE_PERM;
list_for_each_entry(port, &team->port_list, list) {
vlan_features = netdev_increment_features(vlan_features,
@ -985,8 +986,9 @@ static void __team_compute_features(struct team *team)
team->dev->vlan_features = vlan_features;
team->dev->hard_header_len = max_hard_header_len;
flags = team->dev->priv_flags & ~IFF_XMIT_DST_RELEASE;
team->dev->priv_flags = flags | dst_release_flag;
team->dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
if (dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM))
team->dev->priv_flags |= IFF_XMIT_DST_RELEASE;
netdev_change_features(team->dev);
}

2
drivers/net/vxlan.c
View File

@ -2193,7 +2193,7 @@ static void vxlan_setup(struct net_device *dev)
dev->hw_features |= NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_RXCSUM;
dev->hw_features |= NETIF_F_GSO_SOFTWARE;
dev->hw_features |= NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
INIT_LIST_HEAD(&vxlan->next);

2
drivers/net/wan/hdlc_fr.c
View File

@ -1047,7 +1047,7 @@ static void pvc_setup(struct net_device *dev)
dev->flags = IFF_POINTOPOINT;
dev->hard_header_len = 10;
dev->addr_len = 2;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
}
static const struct net_device_ops pvc_ops = {

2
drivers/s390/net/qeth_l3_main.c
View File

@ -3306,7 +3306,7 @@ static int qeth_l3_setup_netdev(struct qeth_card *card)
card->dev->features |= NETIF_F_HW_VLAN_CTAG_TX |
NETIF_F_HW_VLAN_CTAG_RX |
NETIF_F_HW_VLAN_CTAG_FILTER;
card->dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(card->dev);
card->dev->gso_max_size = 15 * PAGE_SIZE;
SET_NETDEV_DEV(card->dev, &card->gdev->dev);

8
include/linux/netdevice.h
View File

@ -1206,6 +1206,7 @@ enum netdev_priv_flags {
IFF_SUPP_NOFCS = 1<<19,
IFF_LIVE_ADDR_CHANGE = 1<<20,
IFF_MACVLAN = 1<<21,
IFF_XMIT_DST_RELEASE_PERM = 1<<22,
};
#define IFF_802_1Q_VLAN IFF_802_1Q_VLAN
@ -1230,6 +1231,7 @@ enum netdev_priv_flags {
#define IFF_SUPP_NOFCS IFF_SUPP_NOFCS
#define IFF_LIVE_ADDR_CHANGE IFF_LIVE_ADDR_CHANGE
#define IFF_MACVLAN IFF_MACVLAN
#define IFF_XMIT_DST_RELEASE_PERM IFF_XMIT_DST_RELEASE_PERM
/**
* struct net_device - The DEVICE structure.
@ -3588,6 +3590,12 @@ static inline bool netif_supports_nofcs(struct net_device *dev)
return dev->priv_flags & IFF_SUPP_NOFCS;
}
/* This device needs to keep skb dst for qdisc enqueue or ndo_start_xmit() */
static inline void netif_keep_dst(struct net_device *dev)
{
dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM);
}
extern struct pernet_operations __net_initdata loopback_net_ops;
/* Logging, debugging and troubleshooting/diagnostic helpers. */

3
net/8021q/vlan_dev.c
View File

@ -799,7 +799,8 @@ void vlan_setup(struct net_device *dev)
ether_setup(dev);
dev->priv_flags |= IFF_802_1Q_VLAN;
dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
dev->priv_flags &= ~IFF_TX_SKB_SHARING;
netif_keep_dst(dev);
dev->tx_queue_len = 0;
dev->netdev_ops = &vlan_netdev_ops;

2
net/atm/clip.c
View File

@ -501,7 +501,7 @@ static void clip_setup(struct net_device *dev)
/* without any more elaborate queuing. 100 is a reasonable */
/* compromise between decent burst-tolerance and protection */
/* against memory hogs. */
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
}
static int clip_create(int number)

19
net/core/dev.c
View File

@ -2665,12 +2665,6 @@ static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device
if (skb->next)
return skb;
/* If device doesn't need skb->dst, release it right now while
* its hot in this cpu cache
*/
if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
skb_dst_drop(skb);
features = netif_skb_features(skb);
skb = validate_xmit_vlan(skb, features);
if (unlikely(!skb))
@ -2811,8 +2805,6 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
* waiting to be sent out; and the qdisc is not running -
* xmit the skb directly.
*/
if (!(dev->priv_flags & IFF_XMIT_DST_RELEASE))
skb_dst_force(skb);
qdisc_bstats_update(q, skb);
@ -2827,7 +2819,6 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
rc = NET_XMIT_SUCCESS;
} else {
skb_dst_force(skb);
rc = q->enqueue(skb, q) & NET_XMIT_MASK;
if (qdisc_run_begin(q)) {
if (unlikely(contended)) {
@ -2924,6 +2915,14 @@ static int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
skb_update_prio(skb);
/* If device/qdisc don't need skb->dst, release it right now while
* its hot in this cpu cache.
*/
if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
skb_dst_drop(skb);
else
skb_dst_force(skb);
txq = netdev_pick_tx(dev, skb, accel_priv);
q = rcu_dereference_bh(txq->qdisc);
@ -6674,7 +6673,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
INIT_LIST_HEAD(&dev->adj_list.lower);
INIT_LIST_HEAD(&dev->all_adj_list.upper);
INIT_LIST_HEAD(&dev->all_adj_list.lower);
dev->priv_flags = IFF_XMIT_DST_RELEASE;
dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
setup(dev);
dev->num_tx_queues = txqs;

2
net/ipv4/ip_gre.c
View File

@ -510,7 +510,7 @@ static int ipgre_tunnel_init(struct net_device *dev)
memcpy(dev->broadcast, &iph->daddr, 4);
dev->flags = IFF_NOARP;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
dev->addr_len = 4;
if (iph->daddr) {

2
net/ipv4/ip_vti.c
View File

@ -364,7 +364,7 @@ static int vti_tunnel_init(struct net_device *dev)
dev->iflink = 0;
dev->addr_len = 4;
dev->features |= NETIF_F_LLTX;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
return ip_tunnel_init(dev);
}

2
net/ipv4/ipip.c
View File

@ -289,7 +289,7 @@ static void ipip_tunnel_setup(struct net_device *dev)
dev->iflink = 0;
dev->addr_len = 4;
dev->features |= NETIF_F_LLTX;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
dev->features |= IPIP_FEATURES;
dev->hw_features |= IPIP_FEATURES;

2
net/ipv6/ip6_gre.c
View File

@ -1242,7 +1242,7 @@ static void ip6gre_tunnel_setup(struct net_device *dev)
dev->flags |= IFF_NOARP;
dev->iflink = 0;
dev->addr_len = sizeof(struct in6_addr);
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
}
static int ip6gre_tunnel_init(struct net_device *dev)

2
net/ipv6/ip6_tunnel.c
View File

@ -1493,7 +1493,7 @@ static void ip6_tnl_dev_setup(struct net_device *dev)
dev->mtu -= 8;
dev->flags |= IFF_NOARP;
dev->addr_len = sizeof(struct in6_addr);
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
/* This perm addr will be used as interface identifier by IPv6 */
dev->addr_assign_type = NET_ADDR_RANDOM;
eth_random_addr(dev->perm_addr);

2
net/ipv6/ip6_vti.c
View File

@ -807,7 +807,7 @@ static void vti6_dev_setup(struct net_device *dev)
dev->mtu = ETH_DATA_LEN;
dev->flags |= IFF_NOARP;
dev->addr_len = sizeof(struct in6_addr);
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
}
/**

2
net/ipv6/sit.c
View File

@ -1364,7 +1364,7 @@ static void ipip6_tunnel_setup(struct net_device *dev)
dev->hard_header_len = LL_MAX_HEADER + t_hlen;
dev->mtu = ETH_DATA_LEN - t_hlen;
dev->flags = IFF_NOARP;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
dev->iflink = 0;
dev->addr_len = 4;
dev->features |= NETIF_F_LLTX;

2
net/sched/cls_flow.c
View File

@ -493,6 +493,8 @@ static int flow_change(struct net *net, struct sk_buff *in_skb,
tcf_exts_change(tp, &fnew->exts, &e);
tcf_em_tree_change(tp, &fnew->ematches, &t);
netif_keep_dst(qdisc_dev(tp->q));
if (tb[TCA_FLOW_KEYS]) {
fnew->keymask = keymask;
fnew->nkeys = nkeys;

1
net/sched/cls_route.c
View File

@ -524,6 +524,7 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
if (f->handle < f1->handle)
break;
netif_keep_dst(qdisc_dev(tp->q));
rcu_assign_pointer(f->next, f1);
rcu_assign_pointer(*fp, f);

3
net/sched/sch_generic.c
View File

@ -47,7 +47,6 @@ EXPORT_SYMBOL(default_qdisc_ops);
static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
{
skb_dst_force(skb);
q->gso_skb = skb;
q->qstats.requeues++;
q->q.qlen++; /* it's still part of the queue */
@ -218,8 +217,6 @@ static inline int qdisc_restart(struct Qdisc *q)
if (unlikely(!skb))
return 0;
WARN_ON_ONCE(skb_dst_is_noref(skb));
root_lock = qdisc_lock(q);
dev = qdisc_dev(q);
txq = skb_get_tx_queue(dev, skb);

2
net/sched/sch_teql.c
View File

@ -470,7 +470,7 @@ static __init void teql_master_setup(struct net_device *dev)
dev->tx_queue_len = 100;
dev->flags = IFF_NOARP;
dev->hard_header_len = LL_MAX_HEADER;
dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
netif_keep_dst(dev);
}
static LIST_HEAD(master_dev_list);