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Kuniyuki reports that the assert for netdev lock fires when
there are netdev event listeners (otherwise we skip the netlink
event generation).
Correct the locking when coming from the notifier.
The NETDEV_XDP_FEAT_CHANGE notifier is already fully locked,
it's the documentation that's incorrect.
Fixes: 99e44f39a8f7 ("netdev: depend on netdev->lock for xdp features")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Reported-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/20250410171019.62128-1-kuniyu@amazon.com
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250416030447.1077551-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The netdevices doc is dangerously broad. At least make it clear
that it's intended for developers, not for users.
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250415172653.811147-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Cross-merge networking fixes after downstream PR (net-6.15-rc2).
Conflict:
Documentation/networking/netdevices.rst
net/core/lock_debug.c
04efcee6ef8d ("net: hold instance lock during NETDEV_CHANGE")
03df156dd3a6 ("xdp: double protect netdev->xdp_flags with netdev->lock")
No adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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We mostly needed rtnl_lock in qstat to make sure the queue count
is stable while we work. For "ops locked" drivers the instance
lock protects the queue count, so we don't have to take rtnl_lock.
For currently ops-locked drivers: netdevsim and bnxt need
the protection from netdev going down while we dump, which
instance lock provides. gve doesn't care.
Reviewed-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250408195956.412733-9-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Explicitly list all the ops structs and what locking they provide.
Use "ops locked" as a term for drivers which have ops called under
the instance lock.
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20250408195956.412733-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Protect xdp_features with netdev->lock. This way pure readers
no longer have to take rtnl_lock to access the field.
This includes calling NETDEV_XDP_FEAT_CHANGE under the lock.
Looks like that's fine for bonding, the only "real" listener,
it's the same as ethtool feature change.
In terms of normal drivers - only GVE need special consideration
(other drivers don't use instance lock or don't support XDP).
It calls xdp_set_features_flag() helper from gve_init_priv() which
in turn is called from gve_reset_recovery() (locked), or prior
to netdev registration. So switch to _locked.
Reviewed-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Acked-by: Harshitha Ramamurthy <hramamurthy@google.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250408195956.412733-6-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Cosmin reports an issue with ipv6_add_dev being called from
NETDEV_CHANGE notifier:
[ 3455.008776] ? ipv6_add_dev+0x370/0x620
[ 3455.010097] ipv6_find_idev+0x96/0xe0
[ 3455.010725] addrconf_add_dev+0x1e/0xa0
[ 3455.011382] addrconf_init_auto_addrs+0xb0/0x720
[ 3455.013537] addrconf_notify+0x35f/0x8d0
[ 3455.014214] notifier_call_chain+0x38/0xf0
[ 3455.014903] netdev_state_change+0x65/0x90
[ 3455.015586] linkwatch_do_dev+0x5a/0x70
[ 3455.016238] rtnl_getlink+0x241/0x3e0
[ 3455.019046] rtnetlink_rcv_msg+0x177/0x5e0
Similarly, linkwatch might get to ipv6_add_dev without ops lock:
[ 3456.656261] ? ipv6_add_dev+0x370/0x620
[ 3456.660039] ipv6_find_idev+0x96/0xe0
[ 3456.660445] addrconf_add_dev+0x1e/0xa0
[ 3456.660861] addrconf_init_auto_addrs+0xb0/0x720
[ 3456.661803] addrconf_notify+0x35f/0x8d0
[ 3456.662236] notifier_call_chain+0x38/0xf0
[ 3456.662676] netdev_state_change+0x65/0x90
[ 3456.663112] linkwatch_do_dev+0x5a/0x70
[ 3456.663529] __linkwatch_run_queue+0xeb/0x200
[ 3456.663990] linkwatch_event+0x21/0x30
[ 3456.664399] process_one_work+0x211/0x610
[ 3456.664828] worker_thread+0x1cc/0x380
[ 3456.665691] kthread+0xf4/0x210
Reclassify NETDEV_CHANGE as a notifier that consistently runs under the
instance lock.
Link: https://lore.kernel.org/netdev/aac073de8beec3e531c86c101b274d434741c28e.camel@nvidia.com/
Reported-by: Cosmin Ratiu <cratiu@nvidia.com>
Tested-by: Cosmin Ratiu <cratiu@nvidia.com>
Fixes: ad7c7b2172c3 ("net: hold netdev instance lock during sysfs operations")
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250404161122.3907628-1-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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We don't have a consistent state yet, but document where we think
we are and where we wanna be.
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250401163452.622454-8-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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There is a couple of places from which we can arrive to ndo_setup_tc
with TC_SETUP_BLOCK/TC_SETUP_FT:
- netlink
- netlink notifier
- netdev notifier
Locking netdev too deep in this call chain seems to be problematic
(especially assuming some/all of the call_netdevice_notifiers
NETDEV_UNREGISTER) might soon be running with the instance lock).
Revert to lockless ndo_setup_tc for TC_SETUP_BLOCK/TC_SETUP_FT. NFT
framework already takes care of most of the locking. Document
the assumptions.
ndo_setup_tc TC_SETUP_BLOCK
nft_block_offload_cmd
nft_chain_offload_cmd
nft_flow_block_chain
nft_flow_offload_chain
nft_flow_rule_offload_abort
nft_flow_rule_offload_commit
nft_flow_rule_offload_commit
nf_tables_commit
nfnetlink_rcv_batch
nfnetlink_rcv_skb_batch
nfnetlink_rcv
nft_offload_netdev_event
NETDEV_UNREGISTER notifier
ndo_setup_tc TC_SETUP_FT
nf_flow_table_offload_cmd
nf_flow_table_offload_setup
nft_unregister_flowtable_hook
nft_register_flowtable_net_hooks
nft_flowtable_update
nf_tables_newflowtable
nfnetlink_rcv_batch (.call NFNL_CB_BATCH)
nft_flowtable_update
nf_tables_newflowtable
nft_flowtable_event
nf_tables_flowtable_event
NETDEV_UNREGISTER notifier
__nft_unregister_flowtable_net_hooks
nft_unregister_flowtable_net_hooks
nf_tables_commit
nfnetlink_rcv_batch (.call NFNL_CB_BATCH)
__nf_tables_abort
nf_tables_abort
nfnetlink_rcv_batch
__nft_release_hook
__nft_release_hooks
nf_tables_pre_exit_net -> module unload
nft_rcv_nl_event
netlink_register_notifier (oh boy)
nft_register_flowtable_net_hooks
nft_flowtable_update
nf_tables_newflowtable
nf_tables_newflowtable
Fixes: c4f0f30b424e ("net: hold netdev instance lock during nft ndo_setup_tc")
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reported-by: syzbot+0afb4bcf91e5a1afdcad@syzkaller.appspotmail.com
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250308044726.1193222-1-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Also clarify ndo_get_stats (that read and write paths can run
concurrently) and mention only RCU.
Cc: Saeed Mahameed <saeed@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250305163732.2766420-14-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Linus suggested during one of past maintainer summits (in context of
a DMA_BUF discussion) that symbol namespaces can be used to prevent
unwelcome but in-tree code from using all exported functions.
Create a namespace for netdev.
Export netdev_rx_queue_restart(), drivers may want to use it since
it gives them a simple and safe way to restart a queue to apply
config changes. But it's both too low level and too actively developed
to be used outside netdev.
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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NETIF_F_LLTX can't be changed via Ethtool and is not a feature,
rather an attribute, very similar to IFF_NO_QUEUE (and hot).
Free one netdev_features_t bit and make it a "hot" private flag.
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Change comments incorrectly mentioning dev_base_lock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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All other user triggered operations are gone from ndo_ioctl, so move
the SIOCBOND family into a custom operation as well.
The .ndo_ioctl() helper is no longer called by the dev_ioctl.c code now,
but there are still a few definitions in obsolete wireless drivers as well
as the appletalk and ieee802154 layers to call SIOCSIFADDR/SIOCGIFADDR
helpers from inside the kernel.
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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In order to further reduce the scope of ndo_do_ioctl(), move
out the SIOCWANDEV handling into a new network device operation
function.
Adjust the prototype to only pass the if_settings sub-structure
in place of the ifreq, and remove the redundant 'cmd' argument
in the process.
Cc: Krzysztof Halasa <khc@pm.waw.pl>
Cc: "Jan \"Yenya\" Kasprzak" <kas@fi.muni.cz>
Cc: Kevin Curtis <kevin.curtis@farsite.co.uk>
Cc: Zhao Qiang <qiang.zhao@nxp.com>
Cc: Martin Schiller <ms@dev.tdt.de>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: linux-x25@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Most users of ndo_do_ioctl are ethernet drivers that implement
the MII commands SIOCGMIIPHY/SIOCGMIIREG/SIOCSMIIREG, or hardware
timestamping with SIOCSHWTSTAMP/SIOCGHWTSTAMP.
Separate these from the few drivers that use ndo_do_ioctl to
implement SIOCBOND, SIOCBR and SIOCWANDEV commands.
This is a purely cosmetic change intended to help readers find
their way through the implementation.
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Vivien Didelot <vivien.didelot@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Vladimir Oltean <olteanv@gmail.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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SIOCDEVPRIVATE ioctl commands are mainly used in really old
drivers, and they have a number of problems:
- They hide behind the normal .ndo_do_ioctl function that
is also used for other things in modern drivers, so it's
hard to spot a driver that actually uses one of these
- Since drivers use a number different calling conventions,
it is impossible to support compat mode for them in
a generic way.
- With all drivers using the same 16 commands codes, there
is no way to introspect the data being passed through
things like strace.
Add a new net_device_ops callback pointer, to address the
first two of these. Separating them from .ndo_do_ioctl
makes it easy to grep for drivers with a .ndo_siocdevprivate
callback, and the unwieldy name hopefully makes it easier
to spot in code review.
By passing the ifreq structure and the ifr_data pointer
separately, it is no longer necessary to overload these,
and the driver can use either one for a given command.
Cc: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Explain the two basic flows of struct net_device's operation.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Fix calling context.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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- add SPDX header;
- adjust title markup;
- mark lists as such;
- adjust identation, whitespaces and blank lines;
- add to networking/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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