linux-stable.git/net/core/dev.h, branch v6.15

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 rtnetlink operations

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

To preserve the atomicity, hold the lock while applying multiple
attributes. The major issue with a full conversion to the instance
lock are software nesting devices (bonding/team/vrf/etc). Those
devices call into the core stack for their lower (potentially
real hw) devices. To avoid explicitly wrapping all those places
into instance lock/unlock, introduce new API boundaries:

- (some) existing dev_xxx calls are now considered "external"
  (to drivers) APIs and they transparently grab the instance
  lock if needed (dev_api.c)
- new netif_xxx calls are internal core stack API (naming is
  sketchy, I've tried netdev_xxx_locked per Jakub's suggestion,
  but it feels a bit verbose; but happy to get back to this
  naming scheme if this is the preference)

This avoids touching most of the existing ioctl/sysfs/drivers paths.

Note the special handling of ndo_xxx_slave operations: I exploit
the fact that none of the drivers that call these functions
need/use instance lock. At the same time, they use dev_xxx
APIs, so the lower device has to be unlocked.

Changes in unregister_netdevice_many_notify (to protect dev->state
with instance lock) trigger lockdep - the loop over close_list
(mostly from cleanup_net) introduces spurious ordering issues.
netdev_lock_cmp_fn has a justification on why it's ok to suppress
for now.

Cc: Saeed Mahameed 
Signed-off-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250305163732.2766420-7-sdf@fomichev.me
Signed-off-by: Jakub Kicinski

net: hold netdev instance lock during ndo_open/ndo_stop

2025-03-06T20:59:43+00:00

For the drivers that use shaper API, switch to the mode where
core stack holds the netdev lock. This affects two drivers:

* iavf - already grabs netdev lock in ndo_open/ndo_stop, so mostly
         remove these
* netdevsim - switch to _locked APIs to avoid deadlock

iavf_close diff is a bit confusing, the existing call looks like this:
  iavf_close() {
    netdev_lock()
    ..
    netdev_unlock()
    wait_event_timeout(down_waitqueue)
  }

I change it to the following:
  netdev_lock()
  iavf_close() {
    ..
    netdev_unlock()
    wait_event_timeout(down_waitqueue)
    netdev_lock() // reusing this lock call
  }
  netdev_unlock()

Since I'm reusing existing netdev_lock call, so it looks like I only
add netdev_unlock.

Cc: Saeed Mahameed 
Signed-off-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250305163732.2766420-2-sdf@fomichev.me
Signed-off-by: Jakub Kicinski

net: page_pool: avoid false positive warning if NAPI was never added

2025-02-08T01:21:03+00:00

We expect NAPI to be in disabled state when page pool is torn down.
But it is also legal if the NAPI is completely uninitialized.

Reviewed-by: Mina Almasry 
Link: https://patch.msgid.link/20250206225638.1387810-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski

net: make netdev netlink ops hold netdev_lock()

2025-01-16T03:13:34+00:00

In prep for dropping rtnl_lock, start locking netdev->lock in netlink
genl ops. We need to be using netdev->up instead of flags & IFF_UP.

We can remove the RCU lock protection for the NAPI since NAPI list
is protected by netdev->lock already.

Reviewed-by: Eric Dumazet 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250115035319.559603-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski

net: add netdev->up protected by netdev_lock()

2025-01-16T03:13:34+00:00

Some uAPI (netdev netlink) hide net_device's sub-objects while
the interface is down to ensure uniform behavior across drivers.
To remove the rtnl_lock dependency from those uAPIs we need a way
to safely tell if the device is down or up.

Add an indication of whether device is open or closed, protected
by netdev->lock. The semantics are the same as IFF_UP, but taking
netdev_lock around every write to ->flags would be a lot of code
churn.

We don't want to blanket the entire open / close path by netdev_lock,
because it will prevent us from applying it to specific structures -
core helpers won't be able to take that lock from any function
called by the drivers on open/close paths.

So the state of the flag is "pessimistic", as in it may report false
negatives, but never false positives.

Reviewed-by: Joe Damato 
Reviewed-by: Eric Dumazet 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250115035319.559603-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski

net: add helpers for lookup and walking netdevs under netdev_lock()

2025-01-16T03:13:33+00:00

Add helpers for accessing netdevs under netdev_lock().
There's some careful handling needed to find the device and lock it
safely, without it getting unregistered, and without taking rtnl_lock
(the latter being the whole point of the new locking, after all).

Reviewed-by: Eric Dumazet 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250115035319.559603-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski

net: hide the definition of dev_get_by_napi_id()

2025-01-11T02:37:01+00:00

There are no module callers of dev_get_by_napi_id(),
and commit d1cacd747768 ("netdev: prevent accessing NAPI instances
from another namespace") proves that getting NAPI by id
needs to be done with care. So hide dev_get_by_napi_id().

Reviewed-by: Jacob Keller 
Reviewed-by: Kalesh AP 
Reviewed-by: Joe Damato 
Link: https://patch.msgid.link/20250110004924.3212260-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski