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1 | .. SPDX-License-Identifier: GPL-2.0 |
2 | ||
3 | ============ | |
4 | Devlink Trap | |
5 | ============ | |
6 | ||
7 | Background | |
8 | ========== | |
9 | ||
10 | Devices capable of offloading the kernel's datapath and perform functions such | |
11 | as bridging and routing must also be able to send specific packets to the | |
12 | kernel (i.e., the CPU) for processing. | |
13 | ||
14 | For example, a device acting as a multicast-aware bridge must be able to send | |
15 | IGMP membership reports to the kernel for processing by the bridge module. | |
16 | Without processing such packets, the bridge module could never populate its | |
17 | MDB. | |
18 | ||
19 | As another example, consider a device acting as router which has received an IP | |
20 | packet with a TTL of 1. Upon routing the packet the device must send it to the | |
21 | kernel so that it will route it as well and generate an ICMP Time Exceeded | |
22 | error datagram. Without letting the kernel route such packets itself, utilities | |
23 | such as ``traceroute`` could never work. | |
24 | ||
25 | The fundamental ability of sending certain packets to the kernel for processing | |
26 | is called "packet trapping". | |
27 | ||
28 | Overview | |
29 | ======== | |
30 | ||
31 | The ``devlink-trap`` mechanism allows capable device drivers to register their | |
32 | supported packet traps with ``devlink`` and report trapped packets to | |
33 | ``devlink`` for further analysis. | |
34 | ||
35 | Upon receiving trapped packets, ``devlink`` will perform a per-trap packets and | |
36 | bytes accounting and potentially report the packet to user space via a netlink | |
37 | event along with all the provided metadata (e.g., trap reason, timestamp, input | |
38 | port). This is especially useful for drop traps (see :ref:`Trap-Types`) | |
39 | as it allows users to obtain further visibility into packet drops that would | |
40 | otherwise be invisible. | |
41 | ||
42 | The following diagram provides a general overview of ``devlink-trap``:: | |
43 | ||
44 | Netlink event: Packet w/ metadata | |
45 | Or a summary of recent drops | |
46 | ^ | |
47 | | | |
48 | Userspace | | |
49 | +---------------------------------------------------+ | |
50 | Kernel | | |
51 | | | |
52 | +-------+--------+ | |
53 | | | | |
54 | | drop_monitor | | |
55 | | | | |
56 | +-------^--------+ | |
57 | | | |
30a4e9a2 | 58 | | Non-control traps |
f3047ca0 IS |
59 | | |
60 | +----+----+ | |
61 | | | Kernel's Rx path | |
62 | | devlink | (non-drop traps) | |
63 | | | | |
64 | +----^----+ ^ | |
65 | | | | |
66 | +-----------+ | |
67 | | | |
68 | +-------+-------+ | |
69 | | | | |
70 | | Device driver | | |
71 | | | | |
72 | +-------^-------+ | |
73 | Kernel | | |
74 | +---------------------------------------------------+ | |
75 | Hardware | | |
76 | | Trapped packet | |
77 | | | |
78 | +--+---+ | |
79 | | | | |
80 | | ASIC | | |
81 | | | | |
82 | +------+ | |
83 | ||
84 | .. _Trap-Types: | |
85 | ||
86 | Trap Types | |
87 | ========== | |
88 | ||
89 | The ``devlink-trap`` mechanism supports the following packet trap types: | |
90 | ||
91 | * ``drop``: Trapped packets were dropped by the underlying device. Packets | |
92 | are only processed by ``devlink`` and not injected to the kernel's Rx path. | |
93 | The trap action (see :ref:`Trap-Actions`) can be changed. | |
94 | * ``exception``: Trapped packets were not forwarded as intended by the | |
95 | underlying device due to an exception (e.g., TTL error, missing neighbour | |
96 | entry) and trapped to the control plane for resolution. Packets are | |
97 | processed by ``devlink`` and injected to the kernel's Rx path. Changing the | |
98 | action of such traps is not allowed, as it can easily break the control | |
99 | plane. | |
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100 | * ``control``: Trapped packets were trapped by the device because these are |
101 | control packets required for the correct functioning of the control plane. | |
102 | For example, ARP request and IGMP query packets. Packets are injected to | |
103 | the kernel's Rx path, but not reported to the kernel's drop monitor. | |
104 | Changing the action of such traps is not allowed, as it can easily break | |
105 | the control plane. | |
f3047ca0 IS |
106 | |
107 | .. _Trap-Actions: | |
108 | ||
109 | Trap Actions | |
110 | ============ | |
111 | ||
112 | The ``devlink-trap`` mechanism supports the following packet trap actions: | |
113 | ||
114 | * ``trap``: The sole copy of the packet is sent to the CPU. | |
115 | * ``drop``: The packet is dropped by the underlying device and a copy is not | |
116 | sent to the CPU. | |
9eefeabe IS |
117 | * ``mirror``: The packet is forwarded by the underlying device and a copy is |
118 | sent to the CPU. | |
f3047ca0 IS |
119 | |
120 | Generic Packet Traps | |
121 | ==================== | |
122 | ||
123 | Generic packet traps are used to describe traps that trap well-defined packets | |
124 | or packets that are trapped due to well-defined conditions (e.g., TTL error). | |
125 | Such traps can be shared by multiple device drivers and their description must | |
126 | be added to the following table: | |
127 | ||
128 | .. list-table:: List of Generic Packet Traps | |
129 | :widths: 5 5 90 | |
130 | ||
131 | * - Name | |
132 | - Type | |
133 | - Description | |
134 | * - ``source_mac_is_multicast`` | |
135 | - ``drop`` | |
136 | - Traps incoming packets that the device decided to drop because of a | |
137 | multicast source MAC | |
138 | * - ``vlan_tag_mismatch`` | |
139 | - ``drop`` | |
140 | - Traps incoming packets that the device decided to drop in case of VLAN | |
141 | tag mismatch: The ingress bridge port is not configured with a PVID and | |
142 | the packet is untagged or prio-tagged | |
143 | * - ``ingress_vlan_filter`` | |
144 | - ``drop`` | |
145 | - Traps incoming packets that the device decided to drop in case they are | |
146 | tagged with a VLAN that is not configured on the ingress bridge port | |
147 | * - ``ingress_spanning_tree_filter`` | |
148 | - ``drop`` | |
149 | - Traps incoming packets that the device decided to drop in case the STP | |
150 | state of the ingress bridge port is not "forwarding" | |
151 | * - ``port_list_is_empty`` | |
152 | - ``drop`` | |
153 | - Traps packets that the device decided to drop in case they need to be | |
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154 | flooded (e.g., unknown unicast, unregistered multicast) and there are |
155 | no ports the packets should be flooded to | |
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156 | * - ``port_loopback_filter`` |
157 | - ``drop`` | |
158 | - Traps packets that the device decided to drop in case after layer 2 | |
159 | forwarding the only port from which they should be transmitted through | |
160 | is the port from which they were received | |
161 | * - ``blackhole_route`` | |
162 | - ``drop`` | |
163 | - Traps packets that the device decided to drop in case they hit a | |
164 | blackhole route | |
165 | * - ``ttl_value_is_too_small`` | |
166 | - ``exception`` | |
167 | - Traps unicast packets that should be forwarded by the device whose TTL | |
168 | was decremented to 0 or less | |
169 | * - ``tail_drop`` | |
170 | - ``drop`` | |
171 | - Traps packets that the device decided to drop because they could not be | |
172 | enqueued to a transmission queue which is full | |
6896cc4d AC |
173 | * - ``non_ip`` |
174 | - ``drop`` | |
175 | - Traps packets that the device decided to drop because they need to | |
176 | undergo a layer 3 lookup, but are not IP or MPLS packets | |
177 | * - ``uc_dip_over_mc_dmac`` | |
178 | - ``drop`` | |
179 | - Traps packets that the device decided to drop because they need to be | |
180 | routed and they have a unicast destination IP and a multicast destination | |
181 | MAC | |
182 | * - ``dip_is_loopback_address`` | |
183 | - ``drop`` | |
184 | - Traps packets that the device decided to drop because they need to be | |
185 | routed and their destination IP is the loopback address (i.e., 127.0.0.0/8 | |
186 | and ::1/128) | |
187 | * - ``sip_is_mc`` | |
188 | - ``drop`` | |
189 | - Traps packets that the device decided to drop because they need to be | |
190 | routed and their source IP is multicast (i.e., 224.0.0.0/8 and ff::/8) | |
191 | * - ``sip_is_loopback_address`` | |
192 | - ``drop`` | |
193 | - Traps packets that the device decided to drop because they need to be | |
194 | routed and their source IP is the loopback address (i.e., 127.0.0.0/8 and ::1/128) | |
195 | * - ``ip_header_corrupted`` | |
196 | - ``drop`` | |
197 | - Traps packets that the device decided to drop because they need to be | |
198 | routed and their IP header is corrupted: wrong checksum, wrong IP version | |
199 | or too short Internet Header Length (IHL) | |
200 | * - ``ipv4_sip_is_limited_bc`` | |
201 | - ``drop`` | |
202 | - Traps packets that the device decided to drop because they need to be | |
203 | routed and their source IP is limited broadcast (i.e., 255.255.255.255/32) | |
204 | * - ``ipv6_mc_dip_reserved_scope`` | |
205 | - ``drop`` | |
206 | - Traps IPv6 packets that the device decided to drop because they need to | |
207 | be routed and their IPv6 multicast destination IP has a reserved scope | |
208 | (i.e., ffx0::/16) | |
209 | * - ``ipv6_mc_dip_interface_local_scope`` | |
210 | - ``drop`` | |
211 | - Traps IPv6 packets that the device decided to drop because they need to | |
212 | be routed and their IPv6 multicast destination IP has an interface-local scope | |
213 | (i.e., ffx1::/16) | |
3b063ae5 AC |
214 | * - ``mtu_value_is_too_small`` |
215 | - ``exception`` | |
216 | - Traps packets that should have been routed by the device, but were bigger | |
217 | than the MTU of the egress interface | |
218 | * - ``unresolved_neigh`` | |
219 | - ``exception`` | |
220 | - Traps packets that did not have a matching IP neighbour after routing | |
221 | * - ``mc_reverse_path_forwarding`` | |
222 | - ``exception`` | |
223 | - Traps multicast IP packets that failed reverse-path forwarding (RPF) | |
224 | check during multicast routing | |
225 | * - ``reject_route`` | |
226 | - ``exception`` | |
227 | - Traps packets that hit reject routes (i.e., "unreachable", "prohibit") | |
228 | * - ``ipv4_lpm_miss`` | |
229 | - ``exception`` | |
230 | - Traps unicast IPv4 packets that did not match any route | |
231 | * - ``ipv6_lpm_miss`` | |
232 | - ``exception`` | |
233 | - Traps unicast IPv6 packets that did not match any route | |
95f0ead8 AC |
234 | * - ``non_routable_packet`` |
235 | - ``drop`` | |
236 | - Traps packets that the device decided to drop because they are not | |
237 | supposed to be routed. For example, IGMP queries can be flooded by the | |
238 | device in layer 2 and reach the router. Such packets should not be | |
239 | routed and instead dropped | |
13c056ec AC |
240 | * - ``decap_error`` |
241 | - ``exception`` | |
242 | - Traps NVE and IPinIP packets that the device decided to drop because of | |
243 | failure during decapsulation (e.g., packet being too short, reserved | |
244 | bits set in VXLAN header) | |
c3cae491 AC |
245 | * - ``overlay_smac_is_mc`` |
246 | - ``drop`` | |
247 | - Traps NVE packets that the device decided to drop because their overlay | |
248 | source MAC is multicast | |
ecd942a0 JP |
249 | * - ``ingress_flow_action_drop`` |
250 | - ``drop`` | |
251 | - Traps packets dropped during processing of ingress flow action drop | |
252 | * - ``egress_flow_action_drop`` | |
253 | - ``drop`` | |
254 | - Traps packets dropped during processing of egress flow action drop | |
515eac67 IS |
255 | * - ``stp`` |
256 | - ``control`` | |
257 | - Traps STP packets | |
258 | * - ``lacp`` | |
259 | - ``control`` | |
260 | - Traps LACP packets | |
261 | * - ``lldp`` | |
262 | - ``control`` | |
263 | - Traps LLDP packets | |
264 | * - ``igmp_query`` | |
265 | - ``control`` | |
266 | - Traps IGMP Membership Query packets | |
267 | * - ``igmp_v1_report`` | |
268 | - ``control`` | |
269 | - Traps IGMP Version 1 Membership Report packets | |
270 | * - ``igmp_v2_report`` | |
271 | - ``control`` | |
272 | - Traps IGMP Version 2 Membership Report packets | |
273 | * - ``igmp_v3_report`` | |
274 | - ``control`` | |
275 | - Traps IGMP Version 3 Membership Report packets | |
276 | * - ``igmp_v2_leave`` | |
277 | - ``control`` | |
278 | - Traps IGMP Version 2 Leave Group packets | |
279 | * - ``mld_query`` | |
280 | - ``control`` | |
281 | - Traps MLD Multicast Listener Query packets | |
282 | * - ``mld_v1_report`` | |
283 | - ``control`` | |
284 | - Traps MLD Version 1 Multicast Listener Report packets | |
285 | * - ``mld_v2_report`` | |
286 | - ``control`` | |
287 | - Traps MLD Version 2 Multicast Listener Report packets | |
288 | * - ``mld_v1_done`` | |
289 | - ``control`` | |
290 | - Traps MLD Version 1 Multicast Listener Done packets | |
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291 | * - ``ipv4_dhcp`` |
292 | - ``control`` | |
293 | - Traps IPv4 DHCP packets | |
294 | * - ``ipv6_dhcp`` | |
295 | - ``control`` | |
296 | - Traps IPv6 DHCP packets | |
297 | * - ``arp_request`` | |
298 | - ``control`` | |
299 | - Traps ARP request packets | |
300 | * - ``arp_response`` | |
301 | - ``control`` | |
302 | - Traps ARP response packets | |
303 | * - ``arp_overlay`` | |
304 | - ``control`` | |
305 | - Traps NVE-decapsulated ARP packets that reached the overlay network. | |
306 | This is required, for example, when the address that needs to be | |
307 | resolved is a local address | |
308 | * - ``ipv6_neigh_solicit`` | |
309 | - ``control`` | |
310 | - Traps IPv6 Neighbour Solicitation packets | |
311 | * - ``ipv6_neigh_advert`` | |
312 | - ``control`` | |
313 | - Traps IPv6 Neighbour Advertisement packets | |
314 | * - ``ipv4_bfd`` | |
315 | - ``control`` | |
316 | - Traps IPv4 BFD packets | |
317 | * - ``ipv6_bfd`` | |
318 | - ``control`` | |
319 | - Traps IPv6 BFD packets | |
320 | * - ``ipv4_ospf`` | |
321 | - ``control`` | |
322 | - Traps IPv4 OSPF packets | |
323 | * - ``ipv6_ospf`` | |
324 | - ``control`` | |
325 | - Traps IPv6 OSPF packets | |
326 | * - ``ipv4_bgp`` | |
327 | - ``control`` | |
328 | - Traps IPv4 BGP packets | |
329 | * - ``ipv6_bgp`` | |
330 | - ``control`` | |
331 | - Traps IPv6 BGP packets | |
332 | * - ``ipv4_vrrp`` | |
333 | - ``control`` | |
334 | - Traps IPv4 VRRP packets | |
335 | * - ``ipv6_vrrp`` | |
336 | - ``control`` | |
337 | - Traps IPv6 VRRP packets | |
338 | * - ``ipv4_pim`` | |
339 | - ``control`` | |
340 | - Traps IPv4 PIM packets | |
341 | * - ``ipv6_pim`` | |
342 | - ``control`` | |
343 | - Traps IPv6 PIM packets | |
344 | * - ``uc_loopback`` | |
345 | - ``control`` | |
346 | - Traps unicast packets that need to be routed through the same layer 3 | |
347 | interface from which they were received. Such packets are routed by the | |
348 | kernel, but also cause it to potentially generate ICMP redirect packets | |
349 | * - ``local_route`` | |
350 | - ``control`` | |
351 | - Traps unicast packets that hit a local route and need to be locally | |
352 | delivered | |
353 | * - ``external_route`` | |
354 | - ``control`` | |
355 | - Traps packets that should be routed through an external interface (e.g., | |
356 | management interface) that does not belong to the same device (e.g., | |
357 | switch ASIC) as the ingress interface | |
358 | * - ``ipv6_uc_dip_link_local_scope`` | |
359 | - ``control`` | |
360 | - Traps unicast IPv6 packets that need to be routed and have a destination | |
361 | IP address with a link-local scope (i.e., fe80::/10). The trap allows | |
362 | device drivers to avoid programming link-local routes, but still receive | |
363 | packets for local delivery | |
364 | * - ``ipv6_dip_all_nodes`` | |
365 | - ``control`` | |
366 | - Traps IPv6 packets that their destination IP address is the "All Nodes | |
367 | Address" (i.e., ff02::1) | |
368 | * - ``ipv6_dip_all_routers`` | |
369 | - ``control`` | |
370 | - Traps IPv6 packets that their destination IP address is the "All Routers | |
371 | Address" (i.e., ff02::2) | |
372 | * - ``ipv6_router_solicit`` | |
373 | - ``control`` | |
374 | - Traps IPv6 Router Solicitation packets | |
375 | * - ``ipv6_router_advert`` | |
376 | - ``control`` | |
377 | - Traps IPv6 Router Advertisement packets | |
378 | * - ``ipv6_redirect`` | |
379 | - ``control`` | |
380 | - Traps IPv6 Redirect Message packets | |
381 | * - ``ipv4_router_alert`` | |
382 | - ``control`` | |
383 | - Traps IPv4 packets that need to be routed and include the Router Alert | |
384 | option. Such packets need to be locally delivered to raw sockets that | |
385 | have the IP_ROUTER_ALERT socket option set | |
386 | * - ``ipv6_router_alert`` | |
387 | - ``control`` | |
388 | - Traps IPv6 packets that need to be routed and include the Router Alert | |
389 | option in their Hop-by-Hop extension header. Such packets need to be | |
390 | locally delivered to raw sockets that have the IPV6_ROUTER_ALERT socket | |
391 | option set | |
392 | * - ``ptp_event`` | |
393 | - ``control`` | |
394 | - Traps PTP time-critical event messages (Sync, Delay_req, Pdelay_Req and | |
395 | Pdelay_Resp) | |
396 | * - ``ptp_general`` | |
397 | - ``control`` | |
398 | - Traps PTP general messages (Announce, Follow_Up, Delay_Resp, | |
399 | Pdelay_Resp_Follow_Up, management and signaling) | |
5eb18a2b IS |
400 | * - ``flow_action_sample`` |
401 | - ``control`` | |
402 | - Traps packets sampled during processing of flow action sample (e.g., via | |
403 | tc's sample action) | |
404 | * - ``flow_action_trap`` | |
405 | - ``control`` | |
406 | - Traps packets logged during processing of flow action trap (e.g., via | |
407 | tc's trap action) | |
08e335f6 AC |
408 | * - ``early_drop`` |
409 | - ``drop`` | |
410 | - Traps packets dropped due to the RED (Random Early Detection) algorithm | |
411 | (i.e., early drops) | |
f3047ca0 | 412 | |
9e087457 IS |
413 | Driver-specific Packet Traps |
414 | ============================ | |
415 | ||
416 | Device drivers can register driver-specific packet traps, but these must be | |
417 | clearly documented. Such traps can correspond to device-specific exceptions and | |
418 | help debug packet drops caused by these exceptions. The following list includes | |
419 | links to the description of driver-specific traps registered by various device | |
420 | drivers: | |
421 | ||
04e4272c | 422 | * :doc:`netdevsim` |
5b051621 | 423 | * :doc:`mlxsw` |
9e087457 | 424 | |
e750b84d LR |
425 | .. _Generic-Packet-Trap-Groups: |
426 | ||
f3047ca0 IS |
427 | Generic Packet Trap Groups |
428 | ========================== | |
429 | ||
430 | Generic packet trap groups are used to aggregate logically related packet | |
431 | traps. These groups allow the user to batch operations such as setting the trap | |
432 | action of all member traps. In addition, ``devlink-trap`` can report aggregated | |
433 | per-group packets and bytes statistics, in case per-trap statistics are too | |
434 | narrow. The description of these groups must be added to the following table: | |
435 | ||
436 | .. list-table:: List of Generic Packet Trap Groups | |
437 | :widths: 10 90 | |
438 | ||
439 | * - Name | |
440 | - Description | |
441 | * - ``l2_drops`` | |
442 | - Contains packet traps for packets that were dropped by the device during | |
443 | layer 2 forwarding (i.e., bridge) | |
444 | * - ``l3_drops`` | |
678eb199 IS |
445 | - Contains packet traps for packets that were dropped by the device during |
446 | layer 3 forwarding | |
447 | * - ``l3_exceptions`` | |
448 | - Contains packet traps for packets that hit an exception (e.g., TTL | |
449 | error) during layer 3 forwarding | |
f3047ca0 IS |
450 | * - ``buffer_drops`` |
451 | - Contains packet traps for packets that were dropped by the device due to | |
452 | an enqueue decision | |
13c056ec AC |
453 | * - ``tunnel_drops`` |
454 | - Contains packet traps for packets that were dropped by the device during | |
455 | tunnel encapsulation / decapsulation | |
ecd942a0 JP |
456 | * - ``acl_drops`` |
457 | - Contains packet traps for packets that were dropped by the device during | |
458 | ACL processing | |
515eac67 IS |
459 | * - ``stp`` |
460 | - Contains packet traps for STP packets | |
461 | * - ``lacp`` | |
462 | - Contains packet traps for LACP packets | |
463 | * - ``lldp`` | |
464 | - Contains packet traps for LLDP packets | |
465 | * - ``mc_snooping`` | |
466 | - Contains packet traps for IGMP and MLD packets required for multicast | |
467 | snooping | |
d77cfd16 IS |
468 | * - ``dhcp`` |
469 | - Contains packet traps for DHCP packets | |
470 | * - ``neigh_discovery`` | |
471 | - Contains packet traps for neighbour discovery packets (e.g., ARP, IPv6 | |
472 | ND) | |
473 | * - ``bfd`` | |
474 | - Contains packet traps for BFD packets | |
475 | * - ``ospf`` | |
476 | - Contains packet traps for OSPF packets | |
477 | * - ``bgp`` | |
478 | - Contains packet traps for BGP packets | |
479 | * - ``vrrp`` | |
480 | - Contains packet traps for VRRP packets | |
481 | * - ``pim`` | |
482 | - Contains packet traps for PIM packets | |
483 | * - ``uc_loopback`` | |
484 | - Contains a packet trap for unicast loopback packets (i.e., | |
485 | ``uc_loopback``). This trap is singled-out because in cases such as | |
486 | one-armed router it will be constantly triggered. To limit the impact on | |
487 | the CPU usage, a packet trap policer with a low rate can be bound to the | |
488 | group without affecting other traps | |
489 | * - ``local_delivery`` | |
490 | - Contains packet traps for packets that should be locally delivered after | |
491 | routing, but do not match more specific packet traps (e.g., | |
492 | ``ipv4_bgp``) | |
ec4f5b36 IS |
493 | * - ``external_delivery`` |
494 | - Contains packet traps for packets that should be routed through an | |
495 | external interface (e.g., management interface) that does not belong to | |
496 | the same device (e.g., switch ASIC) as the ingress interface | |
d77cfd16 IS |
497 | * - ``ipv6`` |
498 | - Contains packet traps for various IPv6 control packets (e.g., Router | |
499 | Advertisements) | |
500 | * - ``ptp_event`` | |
501 | - Contains packet traps for PTP time-critical event messages (Sync, | |
502 | Delay_req, Pdelay_Req and Pdelay_Resp) | |
503 | * - ``ptp_general`` | |
504 | - Contains packet traps for PTP general messages (Announce, Follow_Up, | |
505 | Delay_Resp, Pdelay_Resp_Follow_Up, management and signaling) | |
5eb18a2b IS |
506 | * - ``acl_sample`` |
507 | - Contains packet traps for packets that were sampled by the device during | |
508 | ACL processing | |
509 | * - ``acl_trap`` | |
510 | - Contains packet traps for packets that were trapped (logged) by the | |
511 | device during ACL processing | |
95766451 | 512 | |
ef7d5c7d IS |
513 | Packet Trap Policers |
514 | ==================== | |
515 | ||
516 | As previously explained, the underlying device can trap certain packets to the | |
517 | CPU for processing. In most cases, the underlying device is capable of handling | |
518 | packet rates that are several orders of magnitude higher compared to those that | |
519 | can be handled by the CPU. | |
520 | ||
521 | Therefore, in order to prevent the underlying device from overwhelming the CPU, | |
522 | devices usually include packet trap policers that are able to police the | |
523 | trapped packets to rates that can be handled by the CPU. | |
524 | ||
525 | The ``devlink-trap`` mechanism allows capable device drivers to register their | |
526 | supported packet trap policers with ``devlink``. The device driver can choose | |
527 | to associate these policers with supported packet trap groups (see | |
528 | :ref:`Generic-Packet-Trap-Groups`) during its initialization, thereby exposing | |
529 | its default control plane policy to user space. | |
530 | ||
531 | Device drivers should allow user space to change the parameters of the policers | |
532 | (e.g., rate, burst size) as well as the association between the policers and | |
533 | trap groups by implementing the relevant callbacks. | |
534 | ||
535 | If possible, device drivers should implement a callback that allows user space | |
536 | to retrieve the number of packets that were dropped by the policer because its | |
537 | configured policy was violated. | |
538 | ||
95766451 IS |
539 | Testing |
540 | ======= | |
541 | ||
542 | See ``tools/testing/selftests/drivers/net/netdevsim/devlink_trap.sh`` for a | |
543 | test covering the core infrastructure. Test cases should be added for any new | |
544 | functionality. | |
545 | ||
546 | Device drivers should focus their tests on device-specific functionality, such | |
547 | as the triggering of supported packet traps. |