* [RFC PATCH net-next v2 0/5] switchdev: avoid duplicate packet forwarding
@ 2015-06-17 21:53 sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 1/5] net: don't reforward packets already forwarded by offload device sfeldma
` (4 more replies)
0 siblings, 5 replies; 7+ messages in thread
From: sfeldma @ 2015-06-17 21:53 UTC (permalink / raw)
To: netdev
Cc: jiri, simon.horman, roopa, ronen.arad, john.r.fastabend, andrew,
f.fainelli, linux, davidch, stephen
From: Scott Feldman <sfeldma@gmail.com>
(RFC because we're at rc7+ now)
v2:
- s/fwd_mark/offload_fwd_mark
- use consume_skb rather than kfree_skb when dropping pkt on egress.
- Use Jiri's suggestion to use ifindex of one of the ports in a group
as the mark for all the ports in the group. This can be done with
no additional storage (no hashtable from v1). To pull it off, we
need some simple recursive routines to walk the netdev tree ensuring
all leaves in the tree (ports) in the same group (e.g. bridge)
belonging to the same switch device will have the same offload fwd mark.
Maybe someone sees a better design for the recusive routines? They're
not too bad, and should cover the stacked driver cases.
v1:
With switchdev support for offloading L2/L3 forwarding data path to a
switch device, we have a general problem where both the device and the
kernel may forward the packet, resulting in duplicate packets on the wire.
Anytime a packet is forwarded by the device and a copy is sent to the CPU,
there is potential for duplicate forwarding, as the kernel may also do a
forwarding lookup and send the packet on the wire.
The specific problem this patch series is interested in solving is avoiding
duplicate packets on bridged ports. There was a previous RFC from Roopa
(http://marc.info/?l=linux-netdev&m=142687073314252&w=2) to address this
problem, but didn't solve the problem of mixed ports in the bridge from
different devices; there was no way to exclude some ports from forwarding
and include others. This RFC solves that problem by tagging the ingressing
packet with a unique mark, and then comparing the packet mark with the
egress port mark, and skip forwarding when there is a match. For the mixed
ports bridge case, only those ports with matching marks are skipped.
The switchdev port driver must do two things:
1) Generate a fwd_mark for each switch port, using some unique key of the
switch device (and optionally port). This is done when the port netdev
is registered or if the port's group membership changes (joins/leaves
a bridge, for example).
2) On packet ingress from port, mark the skb with the ingress port's
fwd_mark. If the device supports it, it's useful to only mark skbs
which were already forwarded by the device. If the device does not
support such indication, all skbs can be marked, even if they're
local dst.
Two new 32-bit fields are added to struct sk_buff and struct netdevice to
hold the fwd_mark. I've wrapped these with CONFIG_NET_SWITCHDEV for now. I
tried using skb->mark for this purpose, but ebtables can overwrite the
skb->mark before the bridge gets it, so that will not work.
In general, this fwd_mark can be used for any case where a packet is
forwarded by the device and a copy is sent to the CPU, to avoid the kernel
re-forwarding the packet. sFlow is another use-case that comes to mind,
but I haven't explored the details.
Scott Feldman (5):
net: don't reforward packets already forwarded by offload device
net: add phys ID compare helper to test if two IDs are the same
switchdev: add offload_fwd_mark generator helper
rocker: add offload_fwd_mark support
switchdev: update documentation for offload_fwd_mark
Documentation/networking/switchdev.txt | 14 +++-
drivers/net/ethernet/rocker/rocker.c | 14 +++-
drivers/net/ethernet/rocker/rocker.h | 1 +
include/linux/netdevice.h | 13 ++++
include/linux/skbuff.h | 4 ++
include/net/switchdev.h | 9 +++
net/core/dev.c | 10 +++
net/switchdev/switchdev.c | 111 ++++++++++++++++++++++++++++++--
8 files changed, 167 insertions(+), 9 deletions(-)
--
1.7.10.4
^ permalink raw reply [flat|nested] 7+ messages in thread
* [RFC PATCH net-next v2 1/5] net: don't reforward packets already forwarded by offload device
2015-06-17 21:53 [RFC PATCH net-next v2 0/5] switchdev: avoid duplicate packet forwarding sfeldma
@ 2015-06-17 21:53 ` sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 2/5] net: add phys ID compare helper to test if two IDs are the same sfeldma
` (3 subsequent siblings)
4 siblings, 0 replies; 7+ messages in thread
From: sfeldma @ 2015-06-17 21:53 UTC (permalink / raw)
To: netdev
Cc: jiri, simon.horman, roopa, ronen.arad, john.r.fastabend, andrew,
f.fainelli, linux, davidch, stephen
From: Scott Feldman <sfeldma@gmail.com>
Just before queuing skb for xmit on port, check if skb has been marked by
switchdev port driver as already fordwarded by device. If so, drop skb. A
non-zero skb->offload_fwd_mark field is set by the switchdev port
driver/device on ingress to indicate the skb has already been forwarded by
the device to egress ports with matching dev->skb_mark. The switchdev port
driver would assign a non-zero dev->skb_mark for each device port netdev
during registration, for example.
Signed-off-by: Scott Feldman <sfeldma@gmail.com>
---
include/linux/netdevice.h | 6 ++++++
include/linux/skbuff.h | 4 ++++
net/core/dev.c | 10 ++++++++++
3 files changed, 20 insertions(+)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e20979d..7be616e1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1448,6 +1448,8 @@ enum netdev_priv_flags {
*
* @xps_maps: XXX: need comments on this one
*
+ * @offload_fwd_mark: Offload device fwding mark
+ *
* @trans_start: Time (in jiffies) of last Tx
* @watchdog_timeo: Represents the timeout that is used by
* the watchdog ( see dev_watchdog() )
@@ -1685,6 +1687,10 @@ struct net_device {
struct xps_dev_maps __rcu *xps_maps;
#endif
+#ifdef CONFIG_NET_SWITCHDEV
+ u32 offload_fwd_mark;
+#endif
+
/* These may be needed for future network-power-down code. */
/*
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d6cdd6e..1533c4f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -506,6 +506,7 @@ static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
* @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS
* @napi_id: id of the NAPI struct this skb came from
* @secmark: security marking
+ * @offload_fwd_mark: fwding offload mark
* @mark: Generic packet mark
* @vlan_proto: vlan encapsulation protocol
* @vlan_tci: vlan tag control information
@@ -653,6 +654,9 @@ struct sk_buff {
#ifdef CONFIG_NETWORK_SECMARK
__u32 secmark;
#endif
+#ifdef CONFIG_NET_SWITCHDEV
+ __u32 offload_fwd_mark;
+#endif
union {
__u32 mark;
__u32 reserved_tailroom;
diff --git a/net/core/dev.c b/net/core/dev.c
index 6778a99..9eb517e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3065,6 +3065,16 @@ static int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
else
skb_dst_force(skb);
+#ifdef CONFIG_NET_SWITCHDEV
+ /* Don't forward if offload device already forwarded */
+ if (skb->offload_fwd_mark &&
+ skb->offload_fwd_mark == dev->offload_fwd_mark) {
+ consume_skb(skb);
+ rc = NET_XMIT_SUCCESS;
+ goto out;
+ }
+#endif
+
txq = netdev_pick_tx(dev, skb, accel_priv);
q = rcu_dereference_bh(txq->qdisc);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH net-next v2 2/5] net: add phys ID compare helper to test if two IDs are the same
2015-06-17 21:53 [RFC PATCH net-next v2 0/5] switchdev: avoid duplicate packet forwarding sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 1/5] net: don't reforward packets already forwarded by offload device sfeldma
@ 2015-06-17 21:53 ` sfeldma
2015-06-18 14:11 ` Sergei Shtylyov
2015-06-17 21:53 ` [RFC PATCH net-next v2 3/5] switchdev: add offload_fwd_mark generator helper sfeldma
` (2 subsequent siblings)
4 siblings, 1 reply; 7+ messages in thread
From: sfeldma @ 2015-06-17 21:53 UTC (permalink / raw)
To: netdev
Cc: jiri, simon.horman, roopa, ronen.arad, john.r.fastabend, andrew,
f.fainelli, linux, davidch, stephen
From: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: Scott Feldman <sfeldma@gmail.com>
---
include/linux/netdevice.h | 7 +++++++
net/switchdev/switchdev.c | 8 ++------
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 7be616e1..63090ce 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -766,6 +766,13 @@ struct netdev_phys_item_id {
unsigned char id_len;
};
+static inline bool netdev_phys_item_id_same(struct netdev_phys_item_id *a,
+ struct netdev_phys_item_id *b)
+{
+ return ((a->id_len == b->id_len) &&
+ (memcmp(a->id, b->id, a->id_len) == 0));
+}
+
typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
struct sk_buff *skb);
diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
index a5d0f8e..00c67a5 100644
--- a/net/switchdev/switchdev.c
+++ b/net/switchdev/switchdev.c
@@ -791,13 +791,9 @@ static struct net_device *switchdev_get_dev_by_nhs(struct fib_info *fi)
if (switchdev_port_attr_get(dev, &attr))
return NULL;
- if (nhsel > 0) {
- if (prev_attr.u.ppid.id_len != attr.u.ppid.id_len)
+ if (nhsel > 0 &&
+ !netdev_phys_item_id_same(&prev_attr.u.ppid, &attr.u.ppid))
return NULL;
- if (memcmp(prev_attr.u.ppid.id, attr.u.ppid.id,
- attr.u.ppid.id_len))
- return NULL;
- }
prev_attr = attr;
}
--
1.7.10.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH net-next v2 3/5] switchdev: add offload_fwd_mark generator helper
2015-06-17 21:53 [RFC PATCH net-next v2 0/5] switchdev: avoid duplicate packet forwarding sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 1/5] net: don't reforward packets already forwarded by offload device sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 2/5] net: add phys ID compare helper to test if two IDs are the same sfeldma
@ 2015-06-17 21:53 ` sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 4/5] rocker: add offload_fwd_mark support sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 5/5] switchdev: update documentation for offload_fwd_mark sfeldma
4 siblings, 0 replies; 7+ messages in thread
From: sfeldma @ 2015-06-17 21:53 UTC (permalink / raw)
To: netdev
Cc: jiri, simon.horman, roopa, ronen.arad, john.r.fastabend, andrew,
f.fainelli, linux, davidch, stephen
From: Scott Feldman <sfeldma@gmail.com>
skb->offload_fwd_mark and dev->offload_fwd_mark are 32-bit and should be
unique for device and may even be unique for a sub-set of ports within
device, so add switchdev helper function to generate unique marks based on
port's switch ID and group_ifindex. group_ifindex would typically be the
container dev's ifindex, such as the bridge's ifindex.
The generator uses a global hash table to store offload_fwd_marks hashed by
{switch ID, group_ifindex} key.
Signed-off-by: Scott Feldman <sfeldma@gmail.com>
---
include/net/switchdev.h | 9 ++++
net/switchdev/switchdev.c | 103 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 112 insertions(+)
diff --git a/include/net/switchdev.h b/include/net/switchdev.h
index 437f8fe..d882902 100644
--- a/include/net/switchdev.h
+++ b/include/net/switchdev.h
@@ -157,6 +157,9 @@ int switchdev_port_fdb_del(struct ndmsg *ndm, struct nlattr *tb[],
int switchdev_port_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,
struct net_device *dev,
struct net_device *filter_dev, int idx);
+void switchdev_port_fwd_mark_set(struct net_device *dev,
+ struct net_device *group_dev,
+ bool joining);
#else
@@ -271,6 +274,12 @@ static inline int switchdev_port_fdb_dump(struct sk_buff *skb,
return -EOPNOTSUPP;
}
+static inline void switchdev_port_fwd_mark_set(struct net_device *dev,
+ struct net_device *group_dev,
+ bool joining)
+{
+}
+
#endif
#endif /* _LINUX_SWITCHDEV_H_ */
diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
index 00c67a5..6cb30bf 100644
--- a/net/switchdev/switchdev.c
+++ b/net/switchdev/switchdev.c
@@ -920,3 +920,106 @@ void switchdev_fib_ipv4_abort(struct fib_info *fi)
fi->fib_net->ipv4.fib_offload_disabled = true;
}
EXPORT_SYMBOL_GPL(switchdev_fib_ipv4_abort);
+
+static bool switchdev_port_same_parent_id(struct net_device *a,
+ struct net_device *b)
+{
+ struct switchdev_attr a_attr = {
+ .id = SWITCHDEV_ATTR_PORT_PARENT_ID,
+ .flags = SWITCHDEV_F_NO_RECURSE,
+ };
+ struct switchdev_attr b_attr = {
+ .id = SWITCHDEV_ATTR_PORT_PARENT_ID,
+ .flags = SWITCHDEV_F_NO_RECURSE,
+ };
+
+ if (switchdev_port_attr_get(a, &a_attr) ||
+ switchdev_port_attr_get(b, &b_attr))
+ return false;
+
+ return netdev_phys_item_id_same(&a_attr.u.ppid, &b_attr.u.ppid);
+}
+
+static u32 switchdev_port_fwd_mark_get(struct net_device *dev,
+ struct net_device *group_dev)
+{
+ struct net_device *lower_dev;
+ struct list_head *iter;
+
+ netdev_for_each_lower_dev(group_dev, lower_dev, iter) {
+ if (lower_dev == dev)
+ continue;
+ if (switchdev_port_same_parent_id(dev, lower_dev))
+ return lower_dev->offload_fwd_mark;
+ return switchdev_port_fwd_mark_get(dev, lower_dev);
+ }
+
+ return dev->ifindex;
+}
+
+static void switchdev_port_fwd_mark_reset(struct net_device *group_dev,
+ u32 old_mark, u32 *reset_mark)
+{
+ struct net_device *lower_dev;
+ struct list_head *iter;
+
+ netdev_for_each_lower_dev(group_dev, lower_dev, iter) {
+ if (lower_dev->offload_fwd_mark == old_mark) {
+ if (!*reset_mark)
+ *reset_mark = lower_dev->ifindex;
+ lower_dev->offload_fwd_mark = *reset_mark;
+ }
+ switchdev_port_fwd_mark_reset(lower_dev, old_mark, reset_mark);
+ }
+}
+
+/**
+ * switchdev_port_fwd_mark_set - Set port offload forwarding mark
+ *
+ * @dev: port device
+ * @group_dev: containing device
+ * @joining: true if dev is joining group; false if leaving group
+ *
+ * An ungrouped port's offload mark is just its ifindex. A grouped
+ * port's (member of a bridge, for example) offload mark is the ifindex
+ * of one of the ports in the group with the same parent (switch) ID.
+ * Ports on the same device in the same group will have the same mark.
+ *
+ * Example:
+ *
+ * br0 ifindex=9
+ * sw1p1 ifindex=2 mark=2
+ * sw1p2 ifindex=3 mark=2
+ * sw2p1 ifindex=4 mark=5
+ * sw2p2 ifindex=5 mark=5
+ *
+ * If sw2p2 leaves the bridge, we'll have:
+ *
+ * br0 ifindex=9
+ * sw1p1 ifindex=2 mark=2
+ * sw1p2 ifindex=3 mark=2
+ * sw2p1 ifindex=4 mark=4
+ * sw2p2 ifindex=5 mark=5
+ */
+void switchdev_port_fwd_mark_set(struct net_device *dev,
+ struct net_device *group_dev,
+ bool joining)
+{
+ u32 mark = dev->ifindex;
+ u32 reset_mark = 0;
+
+ if (group_dev && joining) {
+ mark = switchdev_port_fwd_mark_get(dev, group_dev);
+ } else if (group_dev && !joining) {
+ if (dev->offload_fwd_mark == mark)
+ /* Ohoh, this port was the mark reference port,
+ * but it's leaving the group, so reset the
+ * mark for the remaining ports in the group.
+ */
+ switchdev_port_fwd_mark_reset(group_dev, mark,
+ &reset_mark);
+ }
+
+ dev->offload_fwd_mark = mark;
+}
+EXPORT_SYMBOL_GPL(switchdev_port_fwd_mark_set);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH net-next v2 4/5] rocker: add offload_fwd_mark support
2015-06-17 21:53 [RFC PATCH net-next v2 0/5] switchdev: avoid duplicate packet forwarding sfeldma
` (2 preceding siblings ...)
2015-06-17 21:53 ` [RFC PATCH net-next v2 3/5] switchdev: add offload_fwd_mark generator helper sfeldma
@ 2015-06-17 21:53 ` sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 5/5] switchdev: update documentation for offload_fwd_mark sfeldma
4 siblings, 0 replies; 7+ messages in thread
From: sfeldma @ 2015-06-17 21:53 UTC (permalink / raw)
To: netdev
Cc: jiri, simon.horman, roopa, ronen.arad, john.r.fastabend, andrew,
f.fainelli, linux, davidch, stephen
From: Scott Feldman <sfeldma@gmail.com>
If device flags ingress packet as "fwd offload", mark the
skb->offlaod_fwd_mark using the ingress port's dev->offlaod_fwd_mark. This
will be the hint to the kernel that this packet has already been forwarded
by device to egress ports matching skb->offlaod_fwd_mark.
For rocker, derive port dev->offlaod_fwd_mark based on device switch ID and
port ifindex. If port is bridged, use the bridge ifindex rather than the
port ifindex.
Signed-off-by: Scott Feldman <sfeldma@gmail.com>
---
drivers/net/ethernet/rocker/rocker.c | 14 +++++++++++++-
drivers/net/ethernet/rocker/rocker.h | 1 +
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/rocker/rocker.c b/drivers/net/ethernet/rocker/rocker.c
index d4ec660..b72674c 100644
--- a/drivers/net/ethernet/rocker/rocker.c
+++ b/drivers/net/ethernet/rocker/rocker.c
@@ -4701,6 +4701,7 @@ static int rocker_port_rx_proc(const struct rocker *rocker,
const struct rocker_tlv *attrs[ROCKER_TLV_RX_MAX + 1];
struct sk_buff *skb = rocker_desc_cookie_ptr_get(desc_info);
size_t rx_len;
+ u16 rx_flags = 0;
if (!skb)
return -ENOENT;
@@ -4708,6 +4709,8 @@ static int rocker_port_rx_proc(const struct rocker *rocker,
rocker_tlv_parse_desc(attrs, ROCKER_TLV_RX_MAX, desc_info);
if (!attrs[ROCKER_TLV_RX_FRAG_LEN])
return -EINVAL;
+ if (attrs[ROCKER_TLV_RX_FLAGS])
+ rx_flags = rocker_tlv_get_u16(attrs[ROCKER_TLV_RX_FLAGS]);
rocker_dma_rx_ring_skb_unmap(rocker, attrs);
@@ -4715,6 +4718,9 @@ static int rocker_port_rx_proc(const struct rocker *rocker,
skb_put(skb, rx_len);
skb->protocol = eth_type_trans(skb, rocker_port->dev);
+ if (rx_flags & ROCKER_RX_FLAGS_FWD_OFFLOAD)
+ skb->offload_fwd_mark = rocker_port->dev->offload_fwd_mark;
+
rocker_port->dev->stats.rx_packets++;
rocker_port->dev->stats.rx_bytes += skb->len;
@@ -4852,11 +4858,13 @@ static int rocker_probe_port(struct rocker *rocker, unsigned int port_number)
}
rocker->ports[port_number] = rocker_port;
+ switchdev_port_fwd_mark_set(rocker_port->dev, NULL, false);
+
rocker_port_set_learning(rocker_port, SWITCHDEV_TRANS_NONE);
err = rocker_port_ig_tbl(rocker_port, SWITCHDEV_TRANS_NONE, 0);
if (err) {
- dev_err(&pdev->dev, "install ig port table failed\n");
+ netdev_err(rocker_port->dev, "install ig port table failed\n");
goto err_port_ig_tbl;
}
@@ -4876,6 +4884,7 @@ err_untagged_vlan:
rocker_port_ig_tbl(rocker_port, SWITCHDEV_TRANS_NONE,
ROCKER_OP_FLAG_REMOVE);
err_port_ig_tbl:
+ rocker->ports[port_number] = NULL;
unregister_netdev(dev);
err_register_netdev:
free_netdev(dev);
@@ -5131,6 +5140,7 @@ static int rocker_port_bridge_join(struct rocker_port *rocker_port,
rocker_port_internal_vlan_id_get(rocker_port, bridge->ifindex);
rocker_port->bridge_dev = bridge;
+ switchdev_port_fwd_mark_set(rocker_port->dev, bridge, true);
return rocker_port_vlan_add(rocker_port, SWITCHDEV_TRANS_NONE,
untagged_vid, 0);
@@ -5151,6 +5161,8 @@ static int rocker_port_bridge_leave(struct rocker_port *rocker_port)
rocker_port_internal_vlan_id_get(rocker_port,
rocker_port->dev->ifindex);
+ switchdev_port_fwd_mark_set(rocker_port->dev, rocker_port->bridge_dev,
+ false);
rocker_port->bridge_dev = NULL;
err = rocker_port_vlan_add(rocker_port, SWITCHDEV_TRANS_NONE,
diff --git a/drivers/net/ethernet/rocker/rocker.h b/drivers/net/ethernet/rocker/rocker.h
index c61fbf9..f846c0d 100644
--- a/drivers/net/ethernet/rocker/rocker.h
+++ b/drivers/net/ethernet/rocker/rocker.h
@@ -245,6 +245,7 @@ enum {
#define ROCKER_RX_FLAGS_TCP BIT(5)
#define ROCKER_RX_FLAGS_UDP BIT(6)
#define ROCKER_RX_FLAGS_TCP_UDP_CSUM_GOOD BIT(7)
+#define ROCKER_RX_FLAGS_FWD_OFFLOAD BIT(8)
enum {
ROCKER_TLV_TX_UNSPEC,
--
1.7.10.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [RFC PATCH net-next v2 5/5] switchdev: update documentation for offload_fwd_mark
2015-06-17 21:53 [RFC PATCH net-next v2 0/5] switchdev: avoid duplicate packet forwarding sfeldma
` (3 preceding siblings ...)
2015-06-17 21:53 ` [RFC PATCH net-next v2 4/5] rocker: add offload_fwd_mark support sfeldma
@ 2015-06-17 21:53 ` sfeldma
4 siblings, 0 replies; 7+ messages in thread
From: sfeldma @ 2015-06-17 21:53 UTC (permalink / raw)
To: netdev
Cc: jiri, simon.horman, roopa, ronen.arad, john.r.fastabend, andrew,
f.fainelli, linux, davidch, stephen
From: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: Scott Feldman <sfeldma@gmail.com>
---
Documentation/networking/switchdev.txt | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/Documentation/networking/switchdev.txt b/Documentation/networking/switchdev.txt
index c5d7ade..b864e47 100644
--- a/Documentation/networking/switchdev.txt
+++ b/Documentation/networking/switchdev.txt
@@ -279,8 +279,18 @@ and unknown unicast packets to all ports in domain, if allowed by port's
current STP state. The switch driver, knowing which ports are within which
vlan L2 domain, can program the switch device for flooding. The packet should
also be sent to the port netdev for processing by the bridge driver. The
-bridge should not reflood the packet to the same ports the device flooded.
-XXX: the mechanism to avoid duplicate flood packets is being discuseed.
+bridge should not reflood the packet to the same ports the device flooded,
+otherwise there will be duplicate packets on the wire.
+
+To avoid duplicate packets, the device/driver can mark a packet as already
+forwarded using skb->offload_fwd_mark. The same mark is set on the device
+ports in the domain using dev->offload_fwd_mark. If the skb->offload_fwd_mark
+is non-zero and matches the forwarding egress port's dev->skb_mark, the kernel
+will drop the skb right before transmit on the egress port, with the
+understanding that the device already forwarded the packet on same egress port.
+The driver can use switchdev_port_fwd_mark_set() to set a globally unique mark
+for port's dev->offload_fwd_mark, based on the port's parent ID (switch ID) and
+a group ifindex.
It is possible for the switch device to not handle flooding and push the
packets up to the bridge driver for flooding. This is not ideal as the number
--
1.7.10.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [RFC PATCH net-next v2 2/5] net: add phys ID compare helper to test if two IDs are the same
2015-06-17 21:53 ` [RFC PATCH net-next v2 2/5] net: add phys ID compare helper to test if two IDs are the same sfeldma
@ 2015-06-18 14:11 ` Sergei Shtylyov
0 siblings, 0 replies; 7+ messages in thread
From: Sergei Shtylyov @ 2015-06-18 14:11 UTC (permalink / raw)
To: sfeldma, netdev
Cc: jiri, simon.horman, roopa, ronen.arad, john.r.fastabend, andrew,
f.fainelli, linux, davidch, stephen
Hello.
On 6/18/2015 12:53 AM, sfeldma@gmail.com wrote:
> From: Scott Feldman <sfeldma@gmail.com>
> Signed-off-by: Scott Feldman <sfeldma@gmail.com>
> ---
> include/linux/netdevice.h | 7 +++++++
> net/switchdev/switchdev.c | 8 ++------
> 2 files changed, 9 insertions(+), 6 deletions(-)
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 7be616e1..63090ce 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -766,6 +766,13 @@ struct netdev_phys_item_id {
> unsigned char id_len;
> };
>
> +static inline bool netdev_phys_item_id_same(struct netdev_phys_item_id *a,
> + struct netdev_phys_item_id *b)
> +{
> + return ((a->id_len == b->id_len) &&
> + (memcmp(a->id, b->id, a->id_len) == 0));
Parens around the *return* expression not needed (and neither the ones
around ==).
[...]
WBR, Sergei
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2015-06-18 14:11 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-06-17 21:53 [RFC PATCH net-next v2 0/5] switchdev: avoid duplicate packet forwarding sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 1/5] net: don't reforward packets already forwarded by offload device sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 2/5] net: add phys ID compare helper to test if two IDs are the same sfeldma
2015-06-18 14:11 ` Sergei Shtylyov
2015-06-17 21:53 ` [RFC PATCH net-next v2 3/5] switchdev: add offload_fwd_mark generator helper sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 4/5] rocker: add offload_fwd_mark support sfeldma
2015-06-17 21:53 ` [RFC PATCH net-next v2 5/5] switchdev: update documentation for offload_fwd_mark sfeldma
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