linux.git/drivers/net/netdevsim/netdev.c, branch v6.12.80

netdevsim: set the carrier when the device goes up

2025-10-23T14:20:31+00:00

[ Upstream commit 1a8fed52f7be14e45785e8e54d0d0b50fc17dbd8 ]

Bringing a linked netdevsim device down and then up causes communication
failure because both interfaces lack carrier. Basically a ifdown/ifup on
the interface make the link broken.

Commit 3762ec05a9fbda ("netdevsim: add NAPI support") added supported
for NAPI, calling netif_carrier_off() in nsim_stop(). This patch
re-enables the carrier symmetrically on nsim_open(), in case the device
is linked and the peer is up.

Signed-off-by: Breno Leitao 
Fixes: 3762ec05a9fbda ("netdevsim: add NAPI support")
Reviewed-by: Andrew Lunn 
Link: https://patch.msgid.link/20251014-netdevsim_fix-v2-1-53b40590dae1@debian.org
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

netdevsim: Mark NAPI ID on skb in nsim_rcv

2025-06-27T10:11:33+00:00

[ Upstream commit f71c549b26a33fd62f1e9c7deeba738bfc73fbfc ]

Previously, nsim_rcv was not marking the NAPI ID on the skb, leading to
applications seeing a napi ID of 0 when using SO_INCOMING_NAPI_ID.

To add to the userland confusion, netlink appears to correctly report
the NAPI IDs for netdevsim queues but the resulting file descriptor from
a call to accept() was reporting a NAPI ID of 0.

Signed-off-by: Joe Damato 
Link: https://patch.msgid.link/20250424002746.16891-2-jdamato@fastly.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: drv: netdevsim: don't napi_complete() from netpoll

2025-06-19T13:32:31+00:00

[ Upstream commit 1264971017b4d7141352a7fe29021bdfce5d885d ]

netdevsim supports netpoll. Make sure we don't call napi_complete()
from it, since it may not be scheduled. Breno reports hitting a
warning in napi_complete_done():

WARNING: CPU: 14 PID: 104 at net/core/dev.c:6592 napi_complete_done+0x2cc/0x560
  __napi_poll+0x2d8/0x3a0
  handle_softirqs+0x1fe/0x710

This is presumably after netpoll stole the SCHED bit prematurely.

Reported-by: Breno Leitao 
Fixes: 3762ec05a9fb ("netdevsim: add NAPI support")
Tested-by: Breno Leitao 
Link: https://patch.msgid.link/20250611174643.2769263-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: netdevsim: fix nsim_pp_hold_write()

2024-12-27T13:02:04+00:00

[ Upstream commit b9b8301d369b4c876de5255dbf067b19ba88ac71 ]

nsim_pp_hold_write() has two problems:

1) It may return with rtnl held, as found by syzbot.

2) Its return value does not propagate an error if any.

Fixes: 1580cbcbfe77 ("net: netdevsim: add some fake page pool use")
Reported-by: syzbot 
Signed-off-by: Eric Dumazet 
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/20241216083703.1859921-1-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

netdevsim: fix backwards compatibility in nsim_get_iflink()

2024-06-10T10:51:04+00:00

The default ndo_get_iflink() implementation returns the current ifindex
of the netdev. But the overridden nsim_get_iflink() returns 0 if the
current nsim is not linked, breaking backwards compatibility for
userspace that depend on this behaviour.

Fix the problem by returning the current ifindex if not linked to a
peer.

Fixes: 8debcf5832c3 ("netdevsim: add ndo_get_iflink() implementation")
Reported-by: Yu Watanabe 
Suggested-by: Yu Watanabe 
Signed-off-by: David Wei 
Signed-off-by: David S. Miller

netdevsim: add NAPI support

2024-05-09T01:59:47+00:00

Add NAPI support to netdevim, similar to veth.

* Add a nsim_rq rx queue structure to hold a NAPI instance and a skb
  queue.
* During xmit, store the skb in the peer skb queue and schedule NAPI.
* During napi_poll(), drain the skb queue and pass up the stack.
* Add assoc between rxq and NAPI instance using netif_queue_set_napi().

Signed-off-by: David Wei 
Link: https://lore.kernel.org/r/20240507163228.2066817-2-dw@davidwei.uk
Signed-off-by: Jakub Kicinski

net: annotate writes on dev->mtu from ndo_change_mtu()

2024-05-07T23:19:14+00:00

Simon reported that ndo_change_mtu() methods were never
updated to use WRITE_ONCE(dev->mtu, new_mtu) as hinted
in commit 501a90c94510 ("inet: protect against too small
mtu values.")

We read dev->mtu without holding RTNL in many places,
with READ_ONCE() annotations.

It is time to take care of ndo_change_mtu() methods
to use corresponding WRITE_ONCE()

Signed-off-by: Eric Dumazet 
Reported-by: Simon Horman 
Closes: https://lore.kernel.org/netdev/20240505144608.GB67882@kernel.org/
Reviewed-by: Jacob Keller 
Reviewed-by: Sabrina Dubroca 
Reviewed-by: Simon Horman 
Acked-by: Shannon Nelson 
Link: https://lore.kernel.org/r/20240506102812.3025432-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

net: netdevsim: add some fake page pool use

2024-04-15T18:21:11+00:00

Add very basic page pool use so that we can exercise
the netlink uAPI in a selftest.

Page pool gets created on open, destroyed on close.
But we control allocating of a single page thru debugfs.
This page may survive past the page pool itself so that
we can test orphaned page pools.

Link: https://lore.kernel.org/r/20240412141436.828666-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski

netdevsim: report stats by default, like a real device

2024-04-08T10:40:41+00:00

Real devices should implement qstats. Devices which support
pause or FEC configuration should also report the relevant stats.

nsim was missing FEC stats completely, some of the qstats
and pause stats required toggling a debugfs knob.

Note that the tests which used pause always initialize the setting
so they shouldn't be affected by the different starting value.

Signed-off-by: Jakub Kicinski 
Signed-off-by: David S. Miller

netdevsim: add ndo_get_iflink() implementation

2024-03-01T10:43:10+00:00

Add an implementation for ndo_get_iflink() in netdevsim that shows the
ifindex of the linked peer, if any.

Signed-off-by: David Wei 
Reviewed-by: Maciek Machnikowski 
Signed-off-by: David S. Miller