linux.git/net/core/net-sysfs.c, branch v6.16

net: designate queue counts as "double ops protected" by instance lock

2025-03-25T17:06:49+00:00

Drivers which opt into instance lock protection of ops should
only call set_real_num_*_queues() under the instance lock.
This means that queue counts are double protected (writes
are under both rtnl_lock and instance lock, readers under
either).

Some readers may still be under the rtnl_lock, however, so for
now we need double protection of writers.

OTOH queue API paths are only under the protection of the instance
lock, so we need to validate that the instance is actually locking
ops, otherwise the input checks we do against queue count are racy.

Acked-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250324224537.248800-6-kuba@kernel.org
Signed-off-by: Jakub Kicinski

net: rfs: hash function change

2025-03-25T15:24:13+00:00

RFS is using two kinds of hash tables.

First one is controlled by /proc/sys/net/core/rps_sock_flow_entries = 2^N
and using the N low order bits of the l4 hash is good enough.

Then each RX queue has its own hash table, controlled by
/sys/class/net/eth1/queues/rx-$q/rps_flow_cnt = 2^X

Current hash function, using the X low order bits is suboptimal,
because RSS is usually using Func(hash) = (hash % power_of_two);

For example, with 32 RX queues, 6 low order bits have no entropy
for a given queue.

Switch this hash function to hash_32(hash, log) to increase
chances to use all possible slots and reduce collisions.

Signed-off-by: Eric Dumazet 
Cc: Tom Herbert 
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/20250321171309.634100-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

Revert "net: replace dev_addr_sem with netdev instance lock"

2025-03-19T17:52:00+00:00

This reverts commit df43d8bf10316a7c3b1e47e3cc0057a54df4a5b8.

Cc: Kohei Enju 
Reviewed-by: Kuniyuki Iwashima 
Fixes: df43d8bf1031 ("net: replace dev_addr_sem with netdev instance lock")
Signed-off-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250312190513.1252045-2-sdf@fomichev.me
Tested-by: Lei Yang 
Signed-off-by: Paolo Abeni

net: move misc netdev_lock flavors to a separate header

2025-03-08T17:06:50+00:00

Move the more esoteric helpers for netdev instance lock to
a dedicated header. This avoids growing netdevice.h to infinity
and makes rebuilding the kernel much faster (after touching
the header with the helpers).

The main netdev_lock() / netdev_unlock() functions are used
in static inlines in netdevice.h and will probably be used
most commonly, so keep them in netdevice.h.

Acked-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250307183006.2312761-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski

net: replace dev_addr_sem with netdev instance lock

2025-03-06T20:59:45+00:00

Lockdep reports possible circular dependency in [0]. Instead of
fixing the ordering, replace global dev_addr_sem with netdev
instance lock. Most of the paths that set/get mac are RTNL
protected. Two places where it's not, convert to explicit
locking:
- sysfs address_show
- dev_get_mac_address via dev_ioctl

0: https://netdev-3.bots.linux.dev/vmksft-forwarding-dbg/results/993321/24-router-bridge-1d-lag-sh/stderr

Signed-off-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250305163732.2766420-12-sdf@fomichev.me
Signed-off-by: Jakub Kicinski

net: hold netdev instance lock during sysfs operations

2025-03-06T20:59:44+00:00

Most of them are already covered by the converted dev_xxx APIs.
Add the locking wrappers for the remaining ones.

Cc: Saeed Mahameed 
Signed-off-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250305163732.2766420-9-sdf@fomichev.me
Signed-off-by: Jakub Kicinski

net-sysfs: remove unused initial ret values

2025-02-28T01:38:42+00:00

In some net-sysfs functions the ret value is initialized but never used
as it is always overridden. Remove those.

Signed-off-by: Antoine Tenart 
Reviewed-by: Mateusz Polchlopek 
Link: https://patch.msgid.link/20250226174644.311136-1-atenart@kernel.org
Signed-off-by: Jakub Kicinski

net-sysfs: restore behavior for not running devices

2025-02-24T22:21:23+00:00

modprobe dummy dumdummies=1

Old behavior :

$ cat /sys/class/net/dummy0/carrier
cat: /sys/class/net/dummy0/carrier: Invalid argument

After blamed commit, an empty string is reported.

$ cat /sys/class/net/dummy0/carrier
$

In this commit, I restore the old behavior for carrier,
speed and duplex attributes.

Fixes: 79c61899b5ee ("net-sysfs: remove rtnl_trylock from device attributes")
Signed-off-by: Eric Dumazet 
Reported-by: Marco Leogrande 
Reviewed-by: Antoine Tenart 
Link: https://patch.msgid.link/20250221051223.576726-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

net-sysfs: remove rtnl_trylock from queue attributes

2025-02-06T01:49:08+00:00

Similar to the commit removing remove rtnl_trylock from device
attributes we here apply the same technique to networking queues.

Signed-off-by: Antoine Tenart 
Link: https://patch.msgid.link/20250204170314.146022-5-atenart@kernel.org
Signed-off-by: Jakub Kicinski

net-sysfs: prevent uncleared queues from being re-added

2025-02-06T01:49:08+00:00

With the (upcoming) removal of the rtnl_trylock/restart_syscall logic
and because of how Tx/Rx queues are implemented (and their
requirements), it might happen that a queue is re-added before having
the chance to be cleared. In such rare case, do not complete the queue
addition operation.

Signed-off-by: Antoine Tenart 
Link: https://patch.msgid.link/20250204170314.146022-4-atenart@kernel.org
Signed-off-by: Jakub Kicinski