Add skb_crc32c(), which calculates the CRC32C of a sk_buff. It will
replace __skb_checksum(), which unnecessarily supports arbitrary
checksums. Compared to __skb_checksum(), skb_crc32c():
- Uses the correct type for CRC32C values (u32, not __wsum).
- Does not require the caller to provide a skb_checksum_ops struct.
- Is faster because it does not use indirect calls and does not use
the very slow crc32c_combine().
According to commit 2817a336d4 ("net: skb_checksum: allow custom
update/combine for walking skb") which added __skb_checksum(), the
original motivation for the abstraction layer was to avoid code
duplication for CRC32C and other checksums in the future. However:
- No additional checksums showed up after CRC32C. __skb_checksum()
is only used with the "regular" net checksum and CRC32C.
- Indirect calls are expensive. Commit 2544af0344 ("net: avoid
indirect calls in L4 checksum calculation") worked around this
using the INDIRECT_CALL_1 macro. But that only avoided the indirect
call for the net checksum, and at the cost of an extra branch.
- The checksums use different types (__wsum and u32), causing casts
to be needed.
- It made the checksums of fragments be combined (rather than
chained) for both checksums, despite this being highly
counterproductive for CRC32C due to how slow crc32c_combine() is.
This can clearly be seen in commit 4c2f245496 ("sctp: linearize
early if it's not GSO") which tried to work around this performance
bug. With a dedicated function for each checksum, we can instead
just use the proper strategy for each checksum.
As shown by the following tables, the new function skb_crc32c() is
faster than __skb_checksum(), with the improvement varying greatly from
5% to 2500% depending on the case. The largest improvements come from
fragmented packets, mainly due to eliminating the inefficient
crc32c_combine(). But linear packets are improved too, especially
shorter ones, mainly due to eliminating indirect calls. These
benchmarks were done on AMD Zen 5. On that CPU, Linux uses IBRS instead
of retpoline; an even greater improvement might be seen with retpoline:
Linear sk_buffs
Length in bytes __skb_checksum cycles skb_crc32c cycles
=============== ===================== =================
64 43 18
256 94 77
1420 204 161
16384 1735 1642
Nonlinear sk_buffs (even split between head and one fragment)
Length in bytes __skb_checksum cycles skb_crc32c cycles
=============== ===================== =================
64 579 22
256 829 77
1420 1506 194
16384 4365 1682
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://patch.msgid.link/20250519175012.36581-3-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add a hidden kconfig symbol NET_CRC32C that will group together the
functions that calculate CRC32C checksums of packets, so that these
don't have to be built into NET-enabled kernels that don't need them.
Make skb_crc32c_csum_help() (which is called only when IP_SCTP is
enabled) conditional on this symbol, and make IP_SCTP select it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://patch.msgid.link/20250519175012.36581-2-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Jakub Kicinski says:
====================
tools: ynl-gen: add support for "inherited" selector and therefore TC
Add C codegen support for constructs needed by TC, namely passing
sub-message selector from a lower nest, and sub-messages with
fixed headers.
====================
Link: https://patch.msgid.link/20250520161916.413298-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
TC uses all possible sub-message formats:
- nested attrs
- fixed headers + nested attrs
- fixed headers
- empty
Nested attrs are already supported for rt-link. Add support
for remaining 3. The empty and fixed headers ones are fairly
trivial, we can fake a Binary or Flags type instead of a Nest.
For fixed headers + nest we need to teach nest parsing and
nest put to handle fixed headers.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250520161916.413298-10-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In rtnetlink all submessages had the selector at the same level
of nesting as the submessage. We could refer to the relevant
attribute from the current struct. In TC, stats are one level
of nesting deeper than "kind". Teach the code-gen about structs
which need to be passed a selector by the caller for parsing.
Because structs are "topologically sorted" one pass of propagating
the selectors down is enough.
For generating netlink message we depend on the presence bits
so no selector passing needed there.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250520161916.413298-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
All attribute sets and messages are prefixed with tc-.
The C codegen also adds the family name to all structs.
We end up with names like struct tc_tc_act_attrs.
Remove the tc- prefixes to shorten the names.
This should not impact Python as the attr set names
are never exposed to user, they are only used to refer
to things internally, in the encoder / decoder.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250520161916.413298-6-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
There is a define in the uAPI header called tc_gen which expands
to the "generic" TC action fields. This helps other actions include
the base fields without having to deal with nested structs.
A couple of actions (sample, gact) do not define extra fields,
so the spec used a common tc-gen struct for both of them.
Unfortunately this struct does not exist in C. Let's use gact's
(generic act's) struct for basic actions.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250520161916.413298-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tc-act-stats-attrs and tca-stats-attrs are almost identical.
The only difference is that the latter has sub-message decoding
for app, rather than declaring it as a binary attr.
tc-act-police-attrs and tc-police-attrs are identical but for
the TODO annotations.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250520161916.413298-3-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
These two commits preallocated two per-cpu variables in
ip6_route_info_create() as fib_nh_common_init() and fib6_nh_init()
were expected to be called under RCU.
* commit d27b9c40db ("ipv6: Preallocate nhc_pcpu_rth_output in
ip6_route_info_create().")
* commit 5720a328c3 ("ipv6: Preallocate rt->fib6_nh->rt6i_pcpu in
ip6_route_info_create().")
Now these functions can be called without RCU and can use GFP_KERNEL.
Let's revert the commits.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250516022759.44392-8-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Since commit c4837b9853 ("ipv6: Split ip6_route_info_create()."),
ip6_route_info_create_nh() uses GFP_ATOMIC as it was expected to be
called under RCU.
Now, we can call it without RCU and use GFP_KERNEL.
Let's pass gfp_flags to ip6_route_info_create_nh().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250516022759.44392-7-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit 71c0efb6d1 ("ipv6: Factorise ip6_route_multipath_add().") split
a loop in ip6_route_multipath_add() so that we can put rcu_read_lock()
between ip6_route_info_create() and ip6_route_info_create_nh().
We no longer need to do so as ip6_route_info_create_nh() does not require
RCU now.
Let's revert the commit to simplify the code.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250516022759.44392-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit 169fd62799 ("ipv6: Get rid of RTNL for SIOCADDRT and
RTM_NEWROUTE.") added rcu_read_lock() covering
ip6_route_info_create_nh() and __ip6_ins_rt() to guarantee that
nexthop and netdev will not go away.
However, as reported by syzkaller [0], ip_tun_build_state() calls
dst_cache_init() with GFP_KERNEL during the RCU critical section.
ip6_route_info_create_nh() fetches nexthop or netdev depending on
whether RTA_NH_ID is set, and struct fib6_info holds a refcount
of either of them by nexthop_get() or netdev_get_by_index().
netdev_get_by_index() looks up a dev and calls dev_hold() under RCU.
So, we need RCU only around nexthop_find_by_id() and nexthop_get()
( and a few more nexthop code).
Let's add rcu_read_lock() there and remove rcu_read_lock() in
ip6_route_add() and ip6_route_multipath_add().
Now these functions called from fib6_add() need RCU:
- inet6_rt_notify()
- fib6_drop_pcpu_from() (via fib6_purge_rt())
- rt6_flush_exceptions() (via fib6_purge_rt())
- ip6_ignore_linkdown() (via rt6_multipath_rebalance())
All callers of inet6_rt_notify() need RCU, so rcu_read_lock() is
added there.
[0]:
[ BUG: Invalid wait context ]
6.15.0-rc4-syzkaller-00746-g836b313a14a3 #0 Tainted: G W
----------------------------
syz-executor234/5832 is trying to lock:
ffffffff8e021688 (pcpu_alloc_mutex){+.+.}-{4:4}, at:
pcpu_alloc_noprof+0x284/0x16b0 mm/percpu.c:1782
other info that might help us debug this:
context-{5:5}
1 lock held by syz-executor234/5832:
0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire
include/linux/rcupdate.h:331 [inline]
0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock
include/linux/rcupdate.h:841 [inline]
0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at:
ip6_route_add+0x4d/0x2f0 net/ipv6/route.c:3913
stack backtrace:
CPU: 0 UID: 0 PID: 5832 Comm: syz-executor234 Tainted: G W
6.15.0-rc4-syzkaller-00746-g836b313a14a3 #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 04/29/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_lock_invalid_wait_context kernel/locking/lockdep.c:4831 [inline]
check_wait_context kernel/locking/lockdep.c:4903 [inline]
__lock_acquire+0xbcf/0xd20 kernel/locking/lockdep.c:5185
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
__mutex_lock_common kernel/locking/mutex.c:601 [inline]
__mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
pcpu_alloc_noprof+0x284/0x16b0 mm/percpu.c:1782
dst_cache_init+0x37/0xc0 net/core/dst_cache.c:145
ip_tun_build_state+0x193/0x6b0 net/ipv4/ip_tunnel_core.c:687
lwtunnel_build_state+0x381/0x4c0 net/core/lwtunnel.c:137
fib_nh_common_init+0x129/0x460 net/ipv4/fib_semantics.c:635
fib6_nh_init+0x15e4/0x2030 net/ipv6/route.c:3669
ip6_route_info_create_nh+0x139/0x870 net/ipv6/route.c:3866
ip6_route_add+0xf6/0x2f0 net/ipv6/route.c:3915
inet6_rtm_newroute+0x284/0x1c50 net/ipv6/route.c:5732
rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6955
netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534
netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
sock_sendmsg_nosec net/socket.c:712 [inline]
__sock_sendmsg+0x219/0x270 net/socket.c:727
____sys_sendmsg+0x505/0x830 net/socket.c:2566
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
__sys_sendmsg net/socket.c:2652 [inline]
__do_sys_sendmsg net/socket.c:2657 [inline]
__se_sys_sendmsg net/socket.c:2655 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
Fixes: 169fd62799 ("ipv6: Get rid of RTNL for SIOCADDRT and RTM_NEWROUTE.")
Reported-by: syzbot+bcc12d6799364500fbec@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=bcc12d6799364500fbec
Reported-by: Eric Dumazet <edumazet@google.com>
Closes: https://lore.kernel.org/netdev/CANn89i+r1cGacVC_6n3-A-WSkAa_Nr+pmxJ7Gt+oP-P9by2aGw@mail.gmail.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250516022759.44392-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit f130a0cc1b ("inet: fix lwtunnel_valid_encap_type() lock
imbalance") added the rtnl_is_held argument as a temporary fix while
I'm converting nexthop and IPv6 routing table to per-netns RTNL or RCU.
Now all callers of lwtunnel_valid_encap_type() do not hold RTNL.
Let's remove the argument.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250516022759.44392-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Once allocated, the IPv6 routing table is not freed until
netns is dismantled.
fib6_get_table() uses rcu_read_lock() while iterating
net->ipv6.fib_table_hash[], but it's not needed and
rather confusing.
Because some callers have this pattern,
table = fib6_get_table();
rcu_read_lock();
/* ... use table here ... */
rcu_read_unlock();
[ See: addrconf_get_prefix_route(), ip6_route_del(),
rt6_get_route_info(), rt6_get_dflt_router() ]
and this looks illegal but is actually safe.
Let's remove rcu_read_lock() in fib6_get_table() and pass true
to the last argument of hlist_for_each_entry_rcu() to bypass
the RCU check.
Note that protection is not needed but RCU helper is used to
avoid data-race.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250516022759.44392-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Heiner Kallweit says:
====================
net: phy: fixed_phy: simplifications and improvements
This series includes two types of changes:
- All callers pass PHY_POLL, therefore remove irq argument
- constify the passed struct fixed_phy_status *status
====================
Link: https://patch.msgid.link/4d4c468e-300d-42c7-92a1-eabbdb6be748@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
AFAIU always returning -1 from lockdep's compare function
basically disables checking of dependencies between given
locks. Try to be a little more precise about what guarantees
that instance locks won't deadlock.
Right now we only nest them under protection of rtnl_lock.
Mostly in unregister_netdevice_many() and dev_close_many().
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250517200810.466531-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cover three recent cases:
1. missing ops locking for the lowers during netdev_sync_lower_features
2. missing locking for dev_set_promiscuity (plus netdev_ops_assert_locked
with a comment on why/when it's needed)
3. rcu lock during team_change_rx_flags
Verified that each one triggers when the respective fix is reverted.
Not sure about the placement, but since it all relies on teaming,
added to the teaming directory.
One ugly bit is that I add NETIF_F_LRO to netdevsim; there is no way
to trigger netdev_sync_lower_features without it.
Signed-off-by: Stanislav Fomichev <stfomichev@gmail.com>
Link: https://patch.msgid.link/20250516232205.539266-1-stfomichev@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Function __sctp_write_space() doesn't set poll key, which leads to
ep_poll_callback() waking up all waiters, not only these waiting
for the socket being writable. Set the key properly using
wake_up_interruptible_poll(), which is preferred over the sync
variant, as writers are not woken up before at least half of the
queue is available. Also, TCP does the same.
Signed-off-by: Petr Malat <oss@malat.biz>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20250516081727.1361451-1-oss@malat.biz
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
After having factored out the provider part from mdio_bus.c, we can
make the mdio consumer / device layer a separate module. This also
allows to remove Kconfig symbol MDIO_DEVICE.
The module init / exit functions from mdio_bus.c no longer have to be
called from phy_device.c. The link order defined in
drivers/net/phy/Makefile ensures that init / exit functions are called
in the right order.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/dba6b156-5748-44ce-b5e2-e8dc2fcee5a7@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Gur Stavi says:
====================
queue_api: reduce risk of name collision over txq
Rename local variable in macros from txq to _txq.
When macro parameter get_desc is expended it is likely to have a txq
token that refers to a different txq variable at the caller's site.
====================
Link: https://patch.msgid.link/cover.1747559621.git.gur.stavi@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
