linux.git/net/openvswitch/datapath.h, branch v6.16

openvswitch: Allocate struct ovs_pcpu_storage dynamically

2025-06-17T12:47:46+00:00

PERCPU_MODULE_RESERVE defines the maximum size that can by used for the
per-CPU data size used by modules. This is 8KiB.

Commit 035fcdc4d240c ("openvswitch: Merge three per-CPU structures into
one") restructured the per-CPU memory allocation for the module and
moved the separate alloc_percpu() invocations at module init time to a
static per-CPU variable which is allocated by the module loader.

The size of the per-CPU data section for openvswitch is 6488 bytes which
is ~80% of the available per-CPU memory. Together with a few other
modules it is easy to exhaust the available 8KiB of memory.

Allocate ovs_pcpu_storage dynamically at module init time.

Reported-by: Gal Pressman 
Closes: https://lore.kernel.org/all/c401e017-f8db-4f57-a1cd-89beb979a277@nvidia.com
Fixes: 035fcdc4d240c ("openvswitch: Merge three per-CPU structures into one")
Signed-off-by: Sebastian Andrzej Siewior 
Reviewed-by: Aaron Conole 
Link: https://patch.msgid.link/20250613123629.-XSoQTCu@linutronix.de
Signed-off-by: Paolo Abeni

openvswitch: Move ovs_frag_data_storage into the struct ovs_pcpu_storage

2025-05-15T13:23:31+00:00

ovs_frag_data_storage is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.

Move ovs_frag_data_storage into the struct ovs_pcpu_storage which already
provides locking for the structure.

Cc: Aaron Conole 
Cc: Eelco Chaudron 
Cc: Ilya Maximets 
Cc: dev@openvswitch.org
Signed-off-by: Sebastian Andrzej Siewior 
Reviewed-by: Aaron Conole 
Link: https://patch.msgid.link/20250512092736.229935-10-bigeasy@linutronix.de
Signed-off-by: Paolo Abeni

openvswitch: Use nested-BH locking for ovs_pcpu_storage

2025-05-15T13:23:31+00:00

ovs_pcpu_storage is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.
The data structure can be referenced recursive and there is a recursion
counter to avoid too many recursions.

Add a local_lock_t to the data structure and use
local_lock_nested_bh() for locking. Add an owner of the struct which is
the current task and acquire the lock only if the structure is not owned
by the current task.

Cc: Aaron Conole 
Cc: Eelco Chaudron 
Cc: Ilya Maximets 
Cc: dev@openvswitch.org
Signed-off-by: Sebastian Andrzej Siewior 
Reviewed-by: Aaron Conole 
Link: https://patch.msgid.link/20250512092736.229935-9-bigeasy@linutronix.de
Signed-off-by: Paolo Abeni

openvswitch: Merge three per-CPU structures into one

2025-05-15T13:23:31+00:00

exec_actions_level is a per-CPU integer allocated at compile time.
action_fifos and flow_keys are per-CPU pointer and have their data
allocated at module init time.
There is no gain in splitting it, once the module is allocated, the
structures are allocated.

Merge the three per-CPU variables into ovs_pcpu_storage, adapt callers.

Cc: Aaron Conole 
Cc: Eelco Chaudron 
Cc: Ilya Maximets 
Cc: dev@openvswitch.org
Signed-off-by: Sebastian Andrzej Siewior 
Reviewed-by: Aaron Conole 
Link: https://patch.msgid.link/20250512092736.229935-8-bigeasy@linutronix.de
Signed-off-by: Paolo Abeni

net: openvswitch: fix kernel-doc warnings in internal headers

2025-03-24T16:30:21+00:00

Some field descriptions were missing, some were not very accurate.
Not touching the uAPI header or .c files for now.

Formatting of those comments isn't great in general, but at least
they are not missing anything now.

Before:
  $ ./scripts/kernel-doc -none -Wall net/openvswitch/*.h 2>&1 | wc -l
  16

After:
  $ ./scripts/kernel-doc -none -Wall net/openvswitch/*.h 2>&1 | wc -l
  0

Signed-off-by: Ilya Maximets 
Acked-by: Eelco Chaudron 
Reviewed-by: Aaron Conole 
Link: https://patch.msgid.link/20250320224431.252489-1-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski

Revert "openvswitch: switch to per-action label counting in conntrack"

2025-03-13T09:29:34+00:00

Currently, ovs_ct_set_labels() is only called for confirmed conntrack
entries (ct) within ovs_ct_commit(). However, if the conntrack entry
does not have the labels_ext extension, attempting to allocate it in
ovs_ct_get_conn_labels() for a confirmed entry triggers a warning in
nf_ct_ext_add():

  WARN_ON(nf_ct_is_confirmed(ct));

This happens when the conntrack entry is created externally before OVS
increments net->ct.labels_used. The issue has become more likely since
commit fcb1aa5163b1 ("openvswitch: switch to per-action label counting
in conntrack"), which changed to use per-action label counting and
increment net->ct.labels_used when a flow with ct action is added.

Since there’s no straightforward way to fully resolve this issue at the
moment, this reverts the commit to avoid breaking existing use cases.

Fixes: fcb1aa5163b1 ("openvswitch: switch to per-action label counting in conntrack")
Reported-by: Jianbo Liu 
Signed-off-by: Xin Long 
Acked-by: Aaron Conole 
Link: https://patch.msgid.link/1bdeb2f3a812bca016a225d3de714427b2cd4772.1741457143.git.lucien.xin@gmail.com
Signed-off-by: Paolo Abeni

openvswitch: switch to per-action label counting in conntrack

2024-08-16T02:05:19+00:00

Similar to commit 70f06c115bcc ("sched: act_ct: switch to per-action
label counting"), we should also switch to per-action label counting
in openvswitch conntrack, as Florian suggested.

The difference is that nf_connlabels_get() is called unconditionally
when creating an ct action in ovs_ct_copy_action(). As with these
flows:

  table=0,ip,actions=ct(commit,table=1)
  table=1,ip,actions=ct(commit,exec(set_field:0xac->ct_label),table=2)

it needs to make sure the label ext is created in the 1st flow before
the ct is committed in ovs_ct_commit(). Otherwise, the warning in
nf_ct_ext_add() when creating the label ext in the 2nd flow will
be triggered:

   WARN_ON(nf_ct_is_confirmed(ct));

Signed-off-by: Xin Long 
Reviewed-by: Aaron Conole 
Acked-by: Florian Westphal 
Link: https://patch.msgid.link/6b9347d5c1a0b364e88d900b29a616c3f8e5b1ca.1723483073.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski

net: openvswitch: store sampling probability in cb.

2024-07-06T00:45:47+00:00

When a packet sample is observed, the sampling rate that was used is
important to estimate the real frequency of such event.

Store the probability of the parent sample action in the skb's cb area
and use it in psample action to pass it down to psample module.

Reviewed-by: Aaron Conole 
Acked-by: Eelco Chaudron 
Reviewed-by: Ilya Maximets 
Signed-off-by: Adrian Moreno 
Link: https://patch.msgid.link/20240704085710.353845-7-amorenoz@redhat.com
Signed-off-by: Jakub Kicinski

net/sched: Enable tc skb ext allocation on chain miss only when needed

2022-02-05T10:12:53+00:00

Currently tc skb extension is used to send miss info from
tc to ovs datapath module, and driver to tc. For the tc to ovs
miss it is currently always allocated even if it will not
be used by ovs datapath (as it depends on a requested feature).

Export the static key which is used by openvswitch module to
guard this code path as well, so it will be skipped if ovs
datapath doesn't need it. Enable this code path once
ovs datapath needs it.

Signed-off-by: Paul Blakey 
Reviewed-by: Jamal Hadi Salim 
Signed-off-by: David S. Miller

openvswitch: Introduce per-cpu upcall dispatch

2021-07-16T18:06:33+00:00

The Open vSwitch kernel module uses the upcall mechanism to send
packets from kernel space to user space when it misses in the kernel
space flow table. The upcall sends packets via a Netlink socket.
Currently, a Netlink socket is created for every vport. In this way,
there is a 1:1 mapping between a vport and a Netlink socket.
When a packet is received by a vport, if it needs to be sent to
user space, it is sent via the corresponding Netlink socket.

This mechanism, with various iterations of the corresponding user
space code, has seen some limitations and issues:

* On systems with a large number of vports, there is a correspondingly
large number of Netlink sockets which can limit scaling.
(https://bugzilla.redhat.com/show_bug.cgi?id=1526306)
* Packet reordering on upcalls.
(https://bugzilla.redhat.com/show_bug.cgi?id=1844576)
* A thundering herd issue.
(https://bugzilla.redhat.com/show_bug.cgi?id=1834444)

This patch introduces an alternative, feature-negotiated, upcall
mode using a per-cpu dispatch rather than a per-vport dispatch.

In this mode, the Netlink socket to be used for the upcall is
selected based on the CPU of the thread that is executing the upcall.
In this way, it resolves the issues above as:

a) The number of Netlink sockets scales with the number of CPUs
rather than the number of vports.
b) Ordering per-flow is maintained as packets are distributed to
CPUs based on mechanisms such as RSS and flows are distributed
to a single user space thread.
c) Packets from a flow can only wake up one user space thread.

The corresponding user space code can be found at:
https://mail.openvswitch.org/pipermail/ovs-dev/2021-July/385139.html

Bugzilla: https://bugzilla.redhat.com/1844576
Signed-off-by: Mark Gray 
Acked-by: Flavio Leitner 
Acked-by: Pravin B Shelar 
Signed-off-by: David S. Miller