forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
626 lines
25 KiB
626 lines
25 KiB
.. SPDX-License-Identifier: GPL-2.0 |
|
|
|
============ |
|
Devlink Trap |
|
============ |
|
|
|
Background |
|
========== |
|
|
|
Devices capable of offloading the kernel's datapath and perform functions such |
|
as bridging and routing must also be able to send specific packets to the |
|
kernel (i.e., the CPU) for processing. |
|
|
|
For example, a device acting as a multicast-aware bridge must be able to send |
|
IGMP membership reports to the kernel for processing by the bridge module. |
|
Without processing such packets, the bridge module could never populate its |
|
MDB. |
|
|
|
As another example, consider a device acting as router which has received an IP |
|
packet with a TTL of 1. Upon routing the packet the device must send it to the |
|
kernel so that it will route it as well and generate an ICMP Time Exceeded |
|
error datagram. Without letting the kernel route such packets itself, utilities |
|
such as ``traceroute`` could never work. |
|
|
|
The fundamental ability of sending certain packets to the kernel for processing |
|
is called "packet trapping". |
|
|
|
Overview |
|
======== |
|
|
|
The ``devlink-trap`` mechanism allows capable device drivers to register their |
|
supported packet traps with ``devlink`` and report trapped packets to |
|
``devlink`` for further analysis. |
|
|
|
Upon receiving trapped packets, ``devlink`` will perform a per-trap packets and |
|
bytes accounting and potentially report the packet to user space via a netlink |
|
event along with all the provided metadata (e.g., trap reason, timestamp, input |
|
port). This is especially useful for drop traps (see :ref:`Trap-Types`) |
|
as it allows users to obtain further visibility into packet drops that would |
|
otherwise be invisible. |
|
|
|
The following diagram provides a general overview of ``devlink-trap``:: |
|
|
|
Netlink event: Packet w/ metadata |
|
Or a summary of recent drops |
|
^ |
|
| |
|
Userspace | |
|
+---------------------------------------------------+ |
|
Kernel | |
|
| |
|
+-------+--------+ |
|
| | |
|
| drop_monitor | |
|
| | |
|
+-------^--------+ |
|
| |
|
| Non-control traps |
|
| |
|
+----+----+ |
|
| | Kernel's Rx path |
|
| devlink | (non-drop traps) |
|
| | |
|
+----^----+ ^ |
|
| | |
|
+-----------+ |
|
| |
|
+-------+-------+ |
|
| | |
|
| Device driver | |
|
| | |
|
+-------^-------+ |
|
Kernel | |
|
+---------------------------------------------------+ |
|
Hardware | |
|
| Trapped packet |
|
| |
|
+--+---+ |
|
| | |
|
| ASIC | |
|
| | |
|
+------+ |
|
|
|
.. _Trap-Types: |
|
|
|
Trap Types |
|
========== |
|
|
|
The ``devlink-trap`` mechanism supports the following packet trap types: |
|
|
|
* ``drop``: Trapped packets were dropped by the underlying device. Packets |
|
are only processed by ``devlink`` and not injected to the kernel's Rx path. |
|
The trap action (see :ref:`Trap-Actions`) can be changed. |
|
* ``exception``: Trapped packets were not forwarded as intended by the |
|
underlying device due to an exception (e.g., TTL error, missing neighbour |
|
entry) and trapped to the control plane for resolution. Packets are |
|
processed by ``devlink`` and injected to the kernel's Rx path. Changing the |
|
action of such traps is not allowed, as it can easily break the control |
|
plane. |
|
* ``control``: Trapped packets were trapped by the device because these are |
|
control packets required for the correct functioning of the control plane. |
|
For example, ARP request and IGMP query packets. Packets are injected to |
|
the kernel's Rx path, but not reported to the kernel's drop monitor. |
|
Changing the action of such traps is not allowed, as it can easily break |
|
the control plane. |
|
|
|
.. _Trap-Actions: |
|
|
|
Trap Actions |
|
============ |
|
|
|
The ``devlink-trap`` mechanism supports the following packet trap actions: |
|
|
|
* ``trap``: The sole copy of the packet is sent to the CPU. |
|
* ``drop``: The packet is dropped by the underlying device and a copy is not |
|
sent to the CPU. |
|
* ``mirror``: The packet is forwarded by the underlying device and a copy is |
|
sent to the CPU. |
|
|
|
Generic Packet Traps |
|
==================== |
|
|
|
Generic packet traps are used to describe traps that trap well-defined packets |
|
or packets that are trapped due to well-defined conditions (e.g., TTL error). |
|
Such traps can be shared by multiple device drivers and their description must |
|
be added to the following table: |
|
|
|
.. list-table:: List of Generic Packet Traps |
|
:widths: 5 5 90 |
|
|
|
* - Name |
|
- Type |
|
- Description |
|
* - ``source_mac_is_multicast`` |
|
- ``drop`` |
|
- Traps incoming packets that the device decided to drop because of a |
|
multicast source MAC |
|
* - ``vlan_tag_mismatch`` |
|
- ``drop`` |
|
- Traps incoming packets that the device decided to drop in case of VLAN |
|
tag mismatch: The ingress bridge port is not configured with a PVID and |
|
the packet is untagged or prio-tagged |
|
* - ``ingress_vlan_filter`` |
|
- ``drop`` |
|
- Traps incoming packets that the device decided to drop in case they are |
|
tagged with a VLAN that is not configured on the ingress bridge port |
|
* - ``ingress_spanning_tree_filter`` |
|
- ``drop`` |
|
- Traps incoming packets that the device decided to drop in case the STP |
|
state of the ingress bridge port is not "forwarding" |
|
* - ``port_list_is_empty`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop in case they need to be |
|
flooded (e.g., unknown unicast, unregistered multicast) and there are |
|
no ports the packets should be flooded to |
|
* - ``port_loopback_filter`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop in case after layer 2 |
|
forwarding the only port from which they should be transmitted through |
|
is the port from which they were received |
|
* - ``blackhole_route`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop in case they hit a |
|
blackhole route |
|
* - ``ttl_value_is_too_small`` |
|
- ``exception`` |
|
- Traps unicast packets that should be forwarded by the device whose TTL |
|
was decremented to 0 or less |
|
* - ``tail_drop`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they could not be |
|
enqueued to a transmission queue which is full |
|
* - ``non_ip`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they need to |
|
undergo a layer 3 lookup, but are not IP or MPLS packets |
|
* - ``uc_dip_over_mc_dmac`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they need to be |
|
routed and they have a unicast destination IP and a multicast destination |
|
MAC |
|
* - ``dip_is_loopback_address`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they need to be |
|
routed and their destination IP is the loopback address (i.e., 127.0.0.0/8 |
|
and ::1/128) |
|
* - ``sip_is_mc`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they need to be |
|
routed and their source IP is multicast (i.e., 224.0.0.0/8 and ff::/8) |
|
* - ``sip_is_loopback_address`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they need to be |
|
routed and their source IP is the loopback address (i.e., 127.0.0.0/8 and ::1/128) |
|
* - ``ip_header_corrupted`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they need to be |
|
routed and their IP header is corrupted: wrong checksum, wrong IP version |
|
or too short Internet Header Length (IHL) |
|
* - ``ipv4_sip_is_limited_bc`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they need to be |
|
routed and their source IP is limited broadcast (i.e., 255.255.255.255/32) |
|
* - ``ipv6_mc_dip_reserved_scope`` |
|
- ``drop`` |
|
- Traps IPv6 packets that the device decided to drop because they need to |
|
be routed and their IPv6 multicast destination IP has a reserved scope |
|
(i.e., ffx0::/16) |
|
* - ``ipv6_mc_dip_interface_local_scope`` |
|
- ``drop`` |
|
- Traps IPv6 packets that the device decided to drop because they need to |
|
be routed and their IPv6 multicast destination IP has an interface-local scope |
|
(i.e., ffx1::/16) |
|
* - ``mtu_value_is_too_small`` |
|
- ``exception`` |
|
- Traps packets that should have been routed by the device, but were bigger |
|
than the MTU of the egress interface |
|
* - ``unresolved_neigh`` |
|
- ``exception`` |
|
- Traps packets that did not have a matching IP neighbour after routing |
|
* - ``mc_reverse_path_forwarding`` |
|
- ``exception`` |
|
- Traps multicast IP packets that failed reverse-path forwarding (RPF) |
|
check during multicast routing |
|
* - ``reject_route`` |
|
- ``exception`` |
|
- Traps packets that hit reject routes (i.e., "unreachable", "prohibit") |
|
* - ``ipv4_lpm_miss`` |
|
- ``exception`` |
|
- Traps unicast IPv4 packets that did not match any route |
|
* - ``ipv6_lpm_miss`` |
|
- ``exception`` |
|
- Traps unicast IPv6 packets that did not match any route |
|
* - ``non_routable_packet`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop because they are not |
|
supposed to be routed. For example, IGMP queries can be flooded by the |
|
device in layer 2 and reach the router. Such packets should not be |
|
routed and instead dropped |
|
* - ``decap_error`` |
|
- ``exception`` |
|
- Traps NVE and IPinIP packets that the device decided to drop because of |
|
failure during decapsulation (e.g., packet being too short, reserved |
|
bits set in VXLAN header) |
|
* - ``overlay_smac_is_mc`` |
|
- ``drop`` |
|
- Traps NVE packets that the device decided to drop because their overlay |
|
source MAC is multicast |
|
* - ``ingress_flow_action_drop`` |
|
- ``drop`` |
|
- Traps packets dropped during processing of ingress flow action drop |
|
* - ``egress_flow_action_drop`` |
|
- ``drop`` |
|
- Traps packets dropped during processing of egress flow action drop |
|
* - ``stp`` |
|
- ``control`` |
|
- Traps STP packets |
|
* - ``lacp`` |
|
- ``control`` |
|
- Traps LACP packets |
|
* - ``lldp`` |
|
- ``control`` |
|
- Traps LLDP packets |
|
* - ``igmp_query`` |
|
- ``control`` |
|
- Traps IGMP Membership Query packets |
|
* - ``igmp_v1_report`` |
|
- ``control`` |
|
- Traps IGMP Version 1 Membership Report packets |
|
* - ``igmp_v2_report`` |
|
- ``control`` |
|
- Traps IGMP Version 2 Membership Report packets |
|
* - ``igmp_v3_report`` |
|
- ``control`` |
|
- Traps IGMP Version 3 Membership Report packets |
|
* - ``igmp_v2_leave`` |
|
- ``control`` |
|
- Traps IGMP Version 2 Leave Group packets |
|
* - ``mld_query`` |
|
- ``control`` |
|
- Traps MLD Multicast Listener Query packets |
|
* - ``mld_v1_report`` |
|
- ``control`` |
|
- Traps MLD Version 1 Multicast Listener Report packets |
|
* - ``mld_v2_report`` |
|
- ``control`` |
|
- Traps MLD Version 2 Multicast Listener Report packets |
|
* - ``mld_v1_done`` |
|
- ``control`` |
|
- Traps MLD Version 1 Multicast Listener Done packets |
|
* - ``ipv4_dhcp`` |
|
- ``control`` |
|
- Traps IPv4 DHCP packets |
|
* - ``ipv6_dhcp`` |
|
- ``control`` |
|
- Traps IPv6 DHCP packets |
|
* - ``arp_request`` |
|
- ``control`` |
|
- Traps ARP request packets |
|
* - ``arp_response`` |
|
- ``control`` |
|
- Traps ARP response packets |
|
* - ``arp_overlay`` |
|
- ``control`` |
|
- Traps NVE-decapsulated ARP packets that reached the overlay network. |
|
This is required, for example, when the address that needs to be |
|
resolved is a local address |
|
* - ``ipv6_neigh_solicit`` |
|
- ``control`` |
|
- Traps IPv6 Neighbour Solicitation packets |
|
* - ``ipv6_neigh_advert`` |
|
- ``control`` |
|
- Traps IPv6 Neighbour Advertisement packets |
|
* - ``ipv4_bfd`` |
|
- ``control`` |
|
- Traps IPv4 BFD packets |
|
* - ``ipv6_bfd`` |
|
- ``control`` |
|
- Traps IPv6 BFD packets |
|
* - ``ipv4_ospf`` |
|
- ``control`` |
|
- Traps IPv4 OSPF packets |
|
* - ``ipv6_ospf`` |
|
- ``control`` |
|
- Traps IPv6 OSPF packets |
|
* - ``ipv4_bgp`` |
|
- ``control`` |
|
- Traps IPv4 BGP packets |
|
* - ``ipv6_bgp`` |
|
- ``control`` |
|
- Traps IPv6 BGP packets |
|
* - ``ipv4_vrrp`` |
|
- ``control`` |
|
- Traps IPv4 VRRP packets |
|
* - ``ipv6_vrrp`` |
|
- ``control`` |
|
- Traps IPv6 VRRP packets |
|
* - ``ipv4_pim`` |
|
- ``control`` |
|
- Traps IPv4 PIM packets |
|
* - ``ipv6_pim`` |
|
- ``control`` |
|
- Traps IPv6 PIM packets |
|
* - ``uc_loopback`` |
|
- ``control`` |
|
- Traps unicast packets that need to be routed through the same layer 3 |
|
interface from which they were received. Such packets are routed by the |
|
kernel, but also cause it to potentially generate ICMP redirect packets |
|
* - ``local_route`` |
|
- ``control`` |
|
- Traps unicast packets that hit a local route and need to be locally |
|
delivered |
|
* - ``external_route`` |
|
- ``control`` |
|
- Traps packets that should be routed through an external interface (e.g., |
|
management interface) that does not belong to the same device (e.g., |
|
switch ASIC) as the ingress interface |
|
* - ``ipv6_uc_dip_link_local_scope`` |
|
- ``control`` |
|
- Traps unicast IPv6 packets that need to be routed and have a destination |
|
IP address with a link-local scope (i.e., fe80::/10). The trap allows |
|
device drivers to avoid programming link-local routes, but still receive |
|
packets for local delivery |
|
* - ``ipv6_dip_all_nodes`` |
|
- ``control`` |
|
- Traps IPv6 packets that their destination IP address is the "All Nodes |
|
Address" (i.e., ff02::1) |
|
* - ``ipv6_dip_all_routers`` |
|
- ``control`` |
|
- Traps IPv6 packets that their destination IP address is the "All Routers |
|
Address" (i.e., ff02::2) |
|
* - ``ipv6_router_solicit`` |
|
- ``control`` |
|
- Traps IPv6 Router Solicitation packets |
|
* - ``ipv6_router_advert`` |
|
- ``control`` |
|
- Traps IPv6 Router Advertisement packets |
|
* - ``ipv6_redirect`` |
|
- ``control`` |
|
- Traps IPv6 Redirect Message packets |
|
* - ``ipv4_router_alert`` |
|
- ``control`` |
|
- Traps IPv4 packets that need to be routed and include the Router Alert |
|
option. Such packets need to be locally delivered to raw sockets that |
|
have the IP_ROUTER_ALERT socket option set |
|
* - ``ipv6_router_alert`` |
|
- ``control`` |
|
- Traps IPv6 packets that need to be routed and include the Router Alert |
|
option in their Hop-by-Hop extension header. Such packets need to be |
|
locally delivered to raw sockets that have the IPV6_ROUTER_ALERT socket |
|
option set |
|
* - ``ptp_event`` |
|
- ``control`` |
|
- Traps PTP time-critical event messages (Sync, Delay_req, Pdelay_Req and |
|
Pdelay_Resp) |
|
* - ``ptp_general`` |
|
- ``control`` |
|
- Traps PTP general messages (Announce, Follow_Up, Delay_Resp, |
|
Pdelay_Resp_Follow_Up, management and signaling) |
|
* - ``flow_action_sample`` |
|
- ``control`` |
|
- Traps packets sampled during processing of flow action sample (e.g., via |
|
tc's sample action) |
|
* - ``flow_action_trap`` |
|
- ``control`` |
|
- Traps packets logged during processing of flow action trap (e.g., via |
|
tc's trap action) |
|
* - ``early_drop`` |
|
- ``drop`` |
|
- Traps packets dropped due to the RED (Random Early Detection) algorithm |
|
(i.e., early drops) |
|
* - ``vxlan_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the VXLAN header parsing which |
|
might be because of packet truncation or the I flag is not set. |
|
* - ``llc_snap_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the LLC+SNAP header parsing |
|
* - ``vlan_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the VLAN header parsing. Could |
|
include unexpected packet truncation. |
|
* - ``pppoe_ppp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the PPPoE+PPP header parsing. |
|
This could include finding a session ID of 0xFFFF (which is reserved and |
|
not for use), a PPPoE length which is larger than the frame received or |
|
any common error on this type of header |
|
* - ``mpls_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the MPLS header parsing which |
|
could include unexpected header truncation |
|
* - ``arp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the ARP header parsing |
|
* - ``ip_1_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the first IP header parsing. |
|
This packet trap could include packets which do not pass an IP checksum |
|
check, a header length check (a minimum of 20 bytes), which might suffer |
|
from packet truncation thus the total length field exceeds the received |
|
packet length etc |
|
* - ``ip_n_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the parsing of the last IP |
|
header (the inner one in case of an IP over IP tunnel). The same common |
|
error checking is performed here as for the ip_1_parsing trap |
|
* - ``gre_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the GRE header parsing |
|
* - ``udp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the UDP header parsing. |
|
This packet trap could include checksum errorrs, an improper UDP |
|
length detected (smaller than 8 bytes) or detection of header |
|
truncation. |
|
* - ``tcp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the TCP header parsing. |
|
This could include TCP checksum errors, improper combination of SYN, FIN |
|
and/or RESET etc. |
|
* - ``ipsec_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the IPSEC header parsing |
|
* - ``sctp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the SCTP header parsing. |
|
This would mean that port number 0 was used or that the header is |
|
truncated. |
|
* - ``dccp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the DCCP header parsing |
|
* - ``gtp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the GTP header parsing |
|
* - ``esp_parsing`` |
|
- ``drop`` |
|
- Traps packets dropped due to an error in the ESP header parsing |
|
* - ``blackhole_nexthop`` |
|
- ``drop`` |
|
- Traps packets that the device decided to drop in case they hit a |
|
blackhole nexthop |
|
* - ``dmac_filter`` |
|
- ``drop`` |
|
- Traps incoming packets that the device decided to drop because |
|
the destination MAC is not configured in the MAC table and |
|
the interface is not in promiscuous mode |
|
|
|
Driver-specific Packet Traps |
|
============================ |
|
|
|
Device drivers can register driver-specific packet traps, but these must be |
|
clearly documented. Such traps can correspond to device-specific exceptions and |
|
help debug packet drops caused by these exceptions. The following list includes |
|
links to the description of driver-specific traps registered by various device |
|
drivers: |
|
|
|
* :doc:`netdevsim` |
|
* :doc:`mlxsw` |
|
|
|
.. _Generic-Packet-Trap-Groups: |
|
|
|
Generic Packet Trap Groups |
|
========================== |
|
|
|
Generic packet trap groups are used to aggregate logically related packet |
|
traps. These groups allow the user to batch operations such as setting the trap |
|
action of all member traps. In addition, ``devlink-trap`` can report aggregated |
|
per-group packets and bytes statistics, in case per-trap statistics are too |
|
narrow. The description of these groups must be added to the following table: |
|
|
|
.. list-table:: List of Generic Packet Trap Groups |
|
:widths: 10 90 |
|
|
|
* - Name |
|
- Description |
|
* - ``l2_drops`` |
|
- Contains packet traps for packets that were dropped by the device during |
|
layer 2 forwarding (i.e., bridge) |
|
* - ``l3_drops`` |
|
- Contains packet traps for packets that were dropped by the device during |
|
layer 3 forwarding |
|
* - ``l3_exceptions`` |
|
- Contains packet traps for packets that hit an exception (e.g., TTL |
|
error) during layer 3 forwarding |
|
* - ``buffer_drops`` |
|
- Contains packet traps for packets that were dropped by the device due to |
|
an enqueue decision |
|
* - ``tunnel_drops`` |
|
- Contains packet traps for packets that were dropped by the device during |
|
tunnel encapsulation / decapsulation |
|
* - ``acl_drops`` |
|
- Contains packet traps for packets that were dropped by the device during |
|
ACL processing |
|
* - ``stp`` |
|
- Contains packet traps for STP packets |
|
* - ``lacp`` |
|
- Contains packet traps for LACP packets |
|
* - ``lldp`` |
|
- Contains packet traps for LLDP packets |
|
* - ``mc_snooping`` |
|
- Contains packet traps for IGMP and MLD packets required for multicast |
|
snooping |
|
* - ``dhcp`` |
|
- Contains packet traps for DHCP packets |
|
* - ``neigh_discovery`` |
|
- Contains packet traps for neighbour discovery packets (e.g., ARP, IPv6 |
|
ND) |
|
* - ``bfd`` |
|
- Contains packet traps for BFD packets |
|
* - ``ospf`` |
|
- Contains packet traps for OSPF packets |
|
* - ``bgp`` |
|
- Contains packet traps for BGP packets |
|
* - ``vrrp`` |
|
- Contains packet traps for VRRP packets |
|
* - ``pim`` |
|
- Contains packet traps for PIM packets |
|
* - ``uc_loopback`` |
|
- Contains a packet trap for unicast loopback packets (i.e., |
|
``uc_loopback``). This trap is singled-out because in cases such as |
|
one-armed router it will be constantly triggered. To limit the impact on |
|
the CPU usage, a packet trap policer with a low rate can be bound to the |
|
group without affecting other traps |
|
* - ``local_delivery`` |
|
- Contains packet traps for packets that should be locally delivered after |
|
routing, but do not match more specific packet traps (e.g., |
|
``ipv4_bgp``) |
|
* - ``external_delivery`` |
|
- Contains packet traps for packets that should be routed through an |
|
external interface (e.g., management interface) that does not belong to |
|
the same device (e.g., switch ASIC) as the ingress interface |
|
* - ``ipv6`` |
|
- Contains packet traps for various IPv6 control packets (e.g., Router |
|
Advertisements) |
|
* - ``ptp_event`` |
|
- Contains packet traps for PTP time-critical event messages (Sync, |
|
Delay_req, Pdelay_Req and Pdelay_Resp) |
|
* - ``ptp_general`` |
|
- Contains packet traps for PTP general messages (Announce, Follow_Up, |
|
Delay_Resp, Pdelay_Resp_Follow_Up, management and signaling) |
|
* - ``acl_sample`` |
|
- Contains packet traps for packets that were sampled by the device during |
|
ACL processing |
|
* - ``acl_trap`` |
|
- Contains packet traps for packets that were trapped (logged) by the |
|
device during ACL processing |
|
* - ``parser_error_drops`` |
|
- Contains packet traps for packets that were marked by the device during |
|
parsing as erroneous |
|
|
|
Packet Trap Policers |
|
==================== |
|
|
|
As previously explained, the underlying device can trap certain packets to the |
|
CPU for processing. In most cases, the underlying device is capable of handling |
|
packet rates that are several orders of magnitude higher compared to those that |
|
can be handled by the CPU. |
|
|
|
Therefore, in order to prevent the underlying device from overwhelming the CPU, |
|
devices usually include packet trap policers that are able to police the |
|
trapped packets to rates that can be handled by the CPU. |
|
|
|
The ``devlink-trap`` mechanism allows capable device drivers to register their |
|
supported packet trap policers with ``devlink``. The device driver can choose |
|
to associate these policers with supported packet trap groups (see |
|
:ref:`Generic-Packet-Trap-Groups`) during its initialization, thereby exposing |
|
its default control plane policy to user space. |
|
|
|
Device drivers should allow user space to change the parameters of the policers |
|
(e.g., rate, burst size) as well as the association between the policers and |
|
trap groups by implementing the relevant callbacks. |
|
|
|
If possible, device drivers should implement a callback that allows user space |
|
to retrieve the number of packets that were dropped by the policer because its |
|
configured policy was violated. |
|
|
|
Testing |
|
======= |
|
|
|
See ``tools/testing/selftests/drivers/net/netdevsim/devlink_trap.sh`` for a |
|
test covering the core infrastructure. Test cases should be added for any new |
|
functionality. |
|
|
|
Device drivers should focus their tests on device-specific functionality, such |
|
as the triggering of supported packet traps.
|
|
|