net/sched: unregister lockdep keys in qdisc_create/qdisc_alloc error path

commit 86735b57c905e775f05de995df35379366b72168 upstream.

Naresh and Eric report several errors (corrupted elements in the

net/sched: unregister lockdep keys in qdisc_create/qdisc_alloc error path

commit 86735b57c905e775f05de995df35379366b72168 upstream.

Naresh and Eric report several errors (corrupted elements in the dynamic
key hash list), when running tdc.py or syzbot. The error path of
qdisc_alloc() and qdisc_create() frees the qdisc memory, but it forgets
to unregister the lockdep key, thus causing use-after-free like the
following one:

==================================================================
BUG: KASAN: slab-use-after-free in lockdep_register_key+0x5f2/0x700
Read of size 8 at addr ffff88811236f2a8 by task ip/7925

CPU: 26 PID: 7925 Comm: ip Kdump: loaded Not tainted 6.9.0-rc2+ #648
Hardware name: Supermicro SYS-6027R-72RF/X9DRH-7TF/7F/iTF/iF, BIOS 3.0 07/26/2013
Call Trace:
<TASK>
dump_stack_lvl+0x7c/0xc0
print_report+0xc9/0x610
kasan_report+0x89/0xc0
lockdep_register_key+0x5f2/0x700
qdisc_alloc+0x21d/0xb60
qdisc_create_dflt+0x63/0x3c0
attach_one_default_qdisc.constprop.37+0x8e/0x170
dev_activate+0x4bd/0xc30
__dev_open+0x275/0x380
__dev_change_flags+0x3f1/0x570
dev_change_flags+0x7c/0x160
do_setlink+0x1ea1/0x34b0
__rtnl_newlink+0x8c9/0x1510
rtnl_newlink+0x61/0x90
rtnetlink_rcv_msg+0x2f0/0xbc0
netlink_rcv_skb+0x120/0x380
netlink_unicast+0x420/0x630
netlink_sendmsg+0x732/0xbc0
__sock_sendmsg+0x1ea/0x280
____sys_sendmsg+0x5a9/0x990
___sys_sendmsg+0xf1/0x180
__sys_sendmsg+0xd3/0x180
do_syscall_64+0x96/0x180
entry_SYSCALL_64_after_hwframe+0x71/0x79
RIP: 0033:0x7f9503f4fa07
Code: 0a 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b9 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
RSP: 002b:00007fff6c729068 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000006630c681 RCX: 00007f9503f4fa07
RDX: 0000000000000000 RSI: 00007fff6c7290d0 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000078
R10: 000000000000009b R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff6c729180 R14: 0000000000000000 R15: 000055bf67dd9040
</TASK>

Allocated by task 7745:
kasan_save_stack+0x1c/0x40
kasan_save_track+0x10/0x30
__kasan_kmalloc+0x7b/0x90
__kmalloc_node+0x1ff/0x460
qdisc_alloc+0xae/0xb60
qdisc_create+0xdd/0xfb0
tc_modify_qdisc+0x37e/0x1960
rtnetlink_rcv_msg+0x2f0/0xbc0
netlink_rcv_skb+0x120/0x380
netlink_unicast+0x420/0x630
netlink_sendmsg+0x732/0xbc0
__sock_sendmsg+0x1ea/0x280
____sys_sendmsg+0x5a9/0x990
___sys_sendmsg+0xf1/0x180
__sys_sendmsg+0xd3/0x180
do_syscall_64+0x96/0x180
entry_SYSCALL_64_after_hwframe+0x71/0x79

Freed by task 7745:
kasan_save_stack+0x1c/0x40
kasan_save_track+0x10/0x30
kasan_save_free_info+0x36/0x60
__kasan_slab_free+0xfe/0x180
kfree+0x113/0x380
qdisc_create+0xafb/0xfb0
tc_modify_qdisc+0x37e/0x1960
rtnetlink_rcv_msg+0x2f0/0xbc0
netlink_rcv_skb+0x120/0x380
netlink_unicast+0x420/0x630
netlink_sendmsg+0x732/0xbc0
__sock_sendmsg+0x1ea/0x280
____sys_sendmsg+0x5a9/0x990
___sys_sendmsg+0xf1/0x180
__sys_sendmsg+0xd3/0x180
do_syscall_64+0x96/0x180
entry_SYSCALL_64_after_hwframe+0x71/0x79

Fix this ensuring that lockdep_unregister_key() is called before the
qdisc struct is freed, also in the error path of qdisc_create() and
qdisc_alloc().

Fixes: af0cb3fa3f9e ("net/sched: fix false lockdep warning on qdisc root lock")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/netdev/20240429221706.1492418-1-naresh.kamboju@linaro.org/
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/2aa1ca0c0a3aa0acc15925c666c777a4b5de553c.1714496886.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

net/sched: fix false lockdep warning on qdisc root lock

[ Upstream commit af0cb3fa3f9ed258d14abab0152e28a0f9593084 ]

Xiumei and Christoph reported the following lockdep splat, complaining of
the qd

net/sched: fix false lockdep warning on qdisc root lock

[ Upstream commit af0cb3fa3f9ed258d14abab0152e28a0f9593084 ]

Xiumei and Christoph reported the following lockdep splat, complaining of
the qdisc root lock being taken twice:

============================================
WARNING: possible recursive locking detected
6.7.0-rc3+ #598 Not tainted
--------------------------------------------
swapper/2/0 is trying to acquire lock:
ffff888177190110 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1560/0x2e70

but task is already holding lock:
ffff88811995a110 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1560/0x2e70

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&sch->q.lock);
lock(&sch->q.lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

5 locks held by swapper/2/0:
#0: ffff888135a09d98 ((&in_dev->mr_ifc_timer)){+.-.}-{0:0}, at: call_timer_fn+0x11a/0x510
#1: ffffffffaaee5260 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x2c0/0x1ed0
#2: ffffffffaaee5200 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x209/0x2e70
#3: ffff88811995a110 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1560/0x2e70
#4: ffffffffaaee5200 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x209/0x2e70

stack backtrace:
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc3+ #598
Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7353+9de0a3cc 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0x4a/0x80
__lock_acquire+0xfdd/0x3150
lock_acquire+0x1ca/0x540
_raw_spin_lock+0x34/0x80
__dev_queue_xmit+0x1560/0x2e70
tcf_mirred_act+0x82e/0x1260 [act_mirred]
tcf_action_exec+0x161/0x480
tcf_classify+0x689/0x1170
prio_enqueue+0x316/0x660 [sch_prio]
dev_qdisc_enqueue+0x46/0x220
__dev_queue_xmit+0x1615/0x2e70
ip_finish_output2+0x1218/0x1ed0
__ip_finish_output+0x8b3/0x1350
ip_output+0x163/0x4e0
igmp_ifc_timer_expire+0x44b/0x930
call_timer_fn+0x1a2/0x510
run_timer_softirq+0x54d/0x11a0
__do_softirq+0x1b3/0x88f
irq_exit_rcu+0x18f/0x1e0
sysvec_apic_timer_interrupt+0x6f/0x90
</IRQ>

This happens when TC does a mirred egress redirect from the root qdisc of
device A to the root qdisc of device B. As long as these two locks aren't
protecting the same qdisc, they can be acquired in chain: add a per-qdisc
lockdep key to silence false warnings.
This dynamic key should safely replace the static key we have in sch_htb:
it was added to allow enqueueing to the device "direct qdisc" while still
holding the qdisc root lock.

v2: don't use static keys anymore in HTB direct qdiscs (thanks Eric Dumazet)

CC: Maxim Mikityanskiy <maxim@isovalent.com>
CC: Xiumei Mu <xmu@redhat.com>
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/451
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/7dc06d6158f72053cf877a82e2a7a5bd23692faa.1713448007.git.dcaratti@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting

mini_Qdisc_pair::p_miniq is a double pointer to mini_Qdisc, initialized
in ingress_init() to point to net_device::miniq_ingre

net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting

mini_Qdisc_pair::p_miniq is a double pointer to mini_Qdisc, initialized
in ingress_init() to point to net_device::miniq_ingress. ingress Qdiscs
access this per-net_device pointer in mini_qdisc_pair_swap(). Similar
for clsact Qdiscs and miniq_egress.

Unfortunately, after introducing RTNL-unlocked RTM_{NEW,DEL,GET}TFILTER
requests (thanks Hillf Danton for the hint), when replacing ingress or
clsact Qdiscs, for example, the old Qdisc ("@old") could access the same
miniq_{in,e}gress pointer(s) concurrently with the new Qdisc ("@new"),
causing race conditions [1] including a use-after-free bug in
mini_qdisc_pair_swap() reported by syzbot:

BUG: KASAN: slab-use-after-free in mini_qdisc_pair_swap+0x1c2/0x1f0 net/sched/sch_generic.c:1573
Write of size 8 at addr ffff888045b31308 by task syz-executor690/14901
...
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:319
print_report mm/kasan/report.c:430 [inline]
kasan_report+0x11c/0x130 mm/kasan/report.c:536
mini_qdisc_pair_swap+0x1c2/0x1f0 net/sched/sch_generic.c:1573
tcf_chain_head_change_item net/sched/cls_api.c:495 [inline]
tcf_chain0_head_change.isra.0+0xb9/0x120 net/sched/cls_api.c:509
tcf_chain_tp_insert net/sched/cls_api.c:1826 [inline]
tcf_chain_tp_insert_unique net/sched/cls_api.c:1875 [inline]
tc_new_tfilter+0x1de6/0x2290 net/sched/cls_api.c:2266
...

@old and @new should not affect each other. In other words, @old should
never modify miniq_{in,e}gress after @new, and @new should not update
@old's RCU state.

Fixing without changing sch_api.c turned out to be difficult (please
refer to Closes: for discussions). Instead, make sure @new's first call
always happen after @old's last call (in {ingress,clsact}_destroy()) has
finished:

In qdisc_graft(), return -EBUSY if @old has any ongoing filter requests,
and call qdisc_destroy() for @old before grafting @new.

Introduce qdisc_refcount_dec_if_one() as the counterpart of
qdisc_refcount_inc_nz() used for filter requests. Introduce a
non-static version of qdisc_destroy() that does a TCQ_F_BUILTIN check,
just like qdisc_put() etc.

Depends on patch "net/sched: Refactor qdisc_graft() for ingress and
clsact Qdiscs".

[1] To illustrate, the syzkaller reproducer adds ingress Qdiscs under
TC_H_ROOT (no longer possible after commit c7cfbd115001 ("net/sched:
sch_ingress: Only create under TC_H_INGRESS")) on eth0 that has 8
transmission queues:

Thread 1 creates ingress Qdisc A (containing mini Qdisc a1 and a2),
then adds a flower filter X to A.

Thread 2 creates another ingress Qdisc B (containing mini Qdisc b1 and
b2) to replace A, then adds a flower filter Y to B.

Thread 1 A's refcnt Thread 2
RTM_NEWQDISC (A, RTNL-locked)
qdisc_create(A) 1
qdisc_graft(A) 9

RTM_NEWTFILTER (X, RTNL-unlocked)
__tcf_qdisc_find(A) 10
tcf_chain0_head_change(A)
mini_qdisc_pair_swap(A) (1st)
|
| RTM_NEWQDISC (B, RTNL-locked)
RCU sync 2 qdisc_graft(B)
| 1 notify_and_destroy(A)
|
tcf_block_release(A) 0 RTM_NEWTFILTER (Y, RTNL-unlocked)
qdisc_destroy(A) tcf_chain0_head_change(B)
tcf_chain0_head_change_cb_del(A) mini_qdisc_pair_swap(B) (2nd)
mini_qdisc_pair_swap(A) (3rd) |
... ...

Here, B calls mini_qdisc_pair_swap(), pointing eth0->miniq_ingress to
its mini Qdisc, b1. Then, A calls mini_qdisc_pair_swap() again during
ingress_destroy(), setting eth0->miniq_ingress to NULL, so ingress
packets on eth0 will not find filter Y in sch_handle_ingress().

This is just one of the possible consequences of concurrently accessing
miniq_{in,e}gress pointers.

Fixes: 7a096d579e8e ("net: sched: ingress: set 'unlocked' flag for Qdisc ops")
Fixes: 87f373921c4e ("net: sched: ingress: set 'unlocked' flag for clsact Qdisc ops")
Reported-by: syzbot+b53a9c0d1ea4ad62da8b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/r/0000000000006cf87705f79acf1a@google.com/
Cc: Hillf Danton <hdanton@sina.com>
Cc: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

show more ...

net: sched: add rcu annotations around qdisc->qdisc_sleeping

syzbot reported a race around qdisc->qdisc_sleeping [1]

It is time we add proper annotations to reads and writes to/from
qdisc->qdisc_sl

net: sched: add rcu annotations around qdisc->qdisc_sleeping

syzbot reported a race around qdisc->qdisc_sleeping [1]

It is time we add proper annotations to reads and writes to/from
qdisc->qdisc_sleeping.

[1]
BUG: KCSAN: data-race in dev_graft_qdisc / qdisc_lookup_rcu

read to 0xffff8881286fc618 of 8 bytes by task 6928 on cpu 1:
qdisc_lookup_rcu+0x192/0x2c0 net/sched/sch_api.c:331
__tcf_qdisc_find+0x74/0x3c0 net/sched/cls_api.c:1174
tc_get_tfilter+0x18f/0x990 net/sched/cls_api.c:2547
rtnetlink_rcv_msg+0x7af/0x8c0 net/core/rtnetlink.c:6386
netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413
netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365
netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
____sys_sendmsg+0x375/0x4c0 net/socket.c:2503
___sys_sendmsg net/socket.c:2557 [inline]
__sys_sendmsg+0x1e3/0x270 net/socket.c:2586
__do_sys_sendmsg net/socket.c:2595 [inline]
__se_sys_sendmsg net/socket.c:2593 [inline]
__x64_sys_sendmsg+0x46/0x50 net/socket.c:2593
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff8881286fc618 of 8 bytes by task 6912 on cpu 0:
dev_graft_qdisc+0x4f/0x80 net/sched/sch_generic.c:1115
qdisc_graft+0x7d0/0xb60 net/sched/sch_api.c:1103
tc_modify_qdisc+0x712/0xf10 net/sched/sch_api.c:1693
rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6395
netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2546
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6413
netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365
netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1913
sock_sendmsg_nosec net/socket.c:724 [inline]
sock_sendmsg net/socket.c:747 [inline]
____sys_sendmsg+0x375/0x4c0 net/socket.c:2503
___sys_sendmsg net/socket.c:2557 [inline]
__sys_sendmsg+0x1e3/0x270 net/socket.c:2586
__do_sys_sendmsg net/socket.c:2595 [inline]
__se_sys_sendmsg net/socket.c:2593 [inline]
__x64_sys_sendmsg+0x46/0x50 net/socket.c:2593
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6912 Comm: syz-executor.5 Not tainted 6.4.0-rc3-syzkaller-00190-g0d85b27b0cc6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023

Fixes: 3a7d0d07a386 ("net: sched: extend Qdisc with rcu")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Vlad Buslov <vladbu@nvidia.com>
Acked-by: Jamal Hadi Salim<jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: sched: Print msecs when transmit queue time out

The kernel will print several warnings in a short period of time
when it stalls. Like this:

First warning:
[ 7100.097547] ------------[ cut here

net: sched: Print msecs when transmit queue time out

The kernel will print several warnings in a short period of time
when it stalls. Like this:

First warning:
[ 7100.097547] ------------[ cut here ]------------
[ 7100.097550] NETDEV WATCHDOG: eno2 (xxx): transmit queue 8 timed out
[ 7100.097571] WARNING: CPU: 8 PID: 0 at net/sched/sch_generic.c:467
dev_watchdog+0x260/0x270
...

Second warning:
[ 7147.756952] rcu: INFO: rcu_preempt self-detected stall on CPU
[ 7147.756958] rcu: 24-....: (59999 ticks this GP) idle=546/1/0x400000000000000
softirq=367 3137/3673146 fqs=13844
[ 7147.756960] (t=60001 jiffies g=4322709 q=133381)
[ 7147.756962] NMI backtrace for cpu 24
...

We calculate that the transmit queue start stall should occur before
7095s according to watchdog_timeo, the rcu start stall at 7087s.
These two times are close together, it is difficult to confirm which
happened first.

To let users know the exact time the stall started, print msecs when
the transmit queue time out.

Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net/sched: fix netdevice reference leaks in attach_default_qdiscs()

In attach_default_qdiscs(), if a dev has multiple queues and queue 0 fails
to attach qdisc because there is no memory in attach_on

net/sched: fix netdevice reference leaks in attach_default_qdiscs()

In attach_default_qdiscs(), if a dev has multiple queues and queue 0 fails
to attach qdisc because there is no memory in attach_one_default_qdisc().
Then dev->qdisc will be noop_qdisc by default. But the other queues may be
able to successfully attach to default qdisc.

In this case, the fallback to noqueue process will be triggered. If the
original attached qdisc is not released and a new one is directly
attached, this will cause netdevice reference leaks.

The following is the bug log:

veth0: default qdisc (fq_codel) fail, fallback to noqueue
unregister_netdevice: waiting for veth0 to become free. Usage count = 32
leaked reference.
qdisc_alloc+0x12e/0x210
qdisc_create_dflt+0x62/0x140
attach_one_default_qdisc.constprop.41+0x44/0x70
dev_activate+0x128/0x290
__dev_open+0x12a/0x190
__dev_change_flags+0x1a2/0x1f0
dev_change_flags+0x23/0x60
do_setlink+0x332/0x1150
__rtnl_newlink+0x52f/0x8e0
rtnl_newlink+0x43/0x70
rtnetlink_rcv_msg+0x140/0x3b0
netlink_rcv_skb+0x50/0x100
netlink_unicast+0x1bb/0x290
netlink_sendmsg+0x37c/0x4e0
sock_sendmsg+0x5f/0x70
____sys_sendmsg+0x208/0x280

Fix this bug by clearing any non-noop qdiscs that may have been assigned
before trying to re-attach.

Fixes: bf6dba76d278 ("net: sched: fallback to qdisc noqueue if default qdisc setup fail")
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Link: https://lore.kernel.org/r/20220826090055.24424-1-wanghai38@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

show more ...

net: sched: remove unnecessary init of qdisc skb head

The memory allocated by using kzallloc_node and kcalloc has been cleared.
Therefore, the structure members of the new qdisc are 0. So there's no

net: sched: remove unnecessary init of qdisc skb head

The memory allocated by using kzallloc_node and kcalloc has been cleared.
Therefore, the structure members of the new qdisc are 0. So there's no
need to explicitly assign a value of 0.

Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: Fix data-races around weight_p and dev_weight_[rt]x_bias.

While reading weight_p, it can be changed concurrently. Thus, we need
to add READ_ONCE() to its reader.

Also, dev_[rt]x_weight can be

net: Fix data-races around weight_p and dev_weight_[rt]x_bias.

While reading weight_p, it can be changed concurrently. Thus, we need
to add READ_ONCE() to its reader.

Also, dev_[rt]x_weight can be read/written at the same time. So, we
need to use READ_ONCE() and WRITE_ONCE() for its access. Moreover, to
use the same weight_p while changing dev_[rt]x_weight, we add a mutex
in proc_do_dev_weight().

Fixes: 3d48b53fb2ae ("net: dev_weight: TX/RX orthogonality")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net/sched: remove hacks added to dev_trans_start() for bonding to work

Now that the bonding driver keeps track of the last TX time of ARP and
NS probes, we effectively revert the following commits:

net/sched: remove hacks added to dev_trans_start() for bonding to work

Now that the bonding driver keeps track of the last TX time of ARP and
NS probes, we effectively revert the following commits:

32d3e51a82d4 ("net_sched: use macvlan real dev trans_start in dev_trans_start()")
07ce76aa9bcf ("net_sched: make dev_trans_start return vlan's real dev trans_start")

Note that the approach of continuing to hack at this function would not
get us very far, hence the desire to take a different approach. DSA is
also a virtual device that uses NETIF_F_LLTX, but there, many uppers
share the same lower (DSA master, i.e. the physical host port of a
switch). By making dev_trans_start() on a DSA interface return the
dev_trans_start() of the master, we effectively assume that all other
DSA interfaces are silent, otherwise this corrupts the validity of the
probe timestamp data from the bonding driver's perspective.

Furthermore, the hacks didn't take into consideration the fact that the
lower interface of @dev may not have been physical either. For example,
VLAN over VLAN, or DSA with 2 masters in a LAG.

And even furthermore, there are NETIF_F_LLTX devices which are not
stacked, like veth. The hack here would not work with those, because it
would not have to provide the bonding driver something to chew at all.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: rename reference+tracking helpers

Netdev reference helpers have a dev_ prefix for historic
reasons. Renaming the old helpers would be too much churn
but we can rename the tracking ones which ar

net: rename reference+tracking helpers

Netdev reference helpers have a dev_ prefix for historic
reasons. Renaming the old helpers would be too much churn
but we can rename the tracking ones which are relatively
recent and should be the default for new code.

Rename:
dev_hold_track() -> netdev_hold()
dev_put_track() -> netdev_put()
dev_replace_track() -> netdev_ref_replace()

Link: https://lore.kernel.org/r/20220608043955.919359-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net_sched: make qdisc_reset() smaller

For some unknown reason qdisc_reset() is using
a convoluted way of freeing two lists of skbs.

Use __skb_queue_purge() instead.

Signed-off-by: Eric Dumazet <ed

net_sched: make qdisc_reset() smaller

For some unknown reason qdisc_reset() is using
a convoluted way of freeing two lists of skbs.

Use __skb_queue_purge() instead.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20220414011004.2378350-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net_sched: add __rcu annotation to netdev->qdisc

syzbot found a data-race [1] which lead me to add __rcu
annotations to netdev->qdisc, and proper accessors
to get LOCKDEP support.

[1]
BUG: KCSAN: d

net_sched: add __rcu annotation to netdev->qdisc

syzbot found a data-race [1] which lead me to add __rcu
annotations to netdev->qdisc, and proper accessors
to get LOCKDEP support.

[1]
BUG: KCSAN: data-race in dev_activate / qdisc_lookup_rcu

write to 0xffff888168ad6410 of 8 bytes by task 13559 on cpu 1:
attach_default_qdiscs net/sched/sch_generic.c:1167 [inline]
dev_activate+0x2ed/0x8f0 net/sched/sch_generic.c:1221
__dev_open+0x2e9/0x3a0 net/core/dev.c:1416
__dev_change_flags+0x167/0x3f0 net/core/dev.c:8139
rtnl_configure_link+0xc2/0x150 net/core/rtnetlink.c:3150
__rtnl_newlink net/core/rtnetlink.c:3489 [inline]
rtnl_newlink+0xf4d/0x13e0 net/core/rtnetlink.c:3529
rtnetlink_rcv_msg+0x745/0x7e0 net/core/rtnetlink.c:5594
netlink_rcv_skb+0x14e/0x250 net/netlink/af_netlink.c:2494
rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5612
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x602/0x6d0 net/netlink/af_netlink.c:1343
netlink_sendmsg+0x728/0x850 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg net/socket.c:725 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2413
___sys_sendmsg net/socket.c:2467 [inline]
__sys_sendmsg+0x195/0x230 net/socket.c:2496
__do_sys_sendmsg net/socket.c:2505 [inline]
__se_sys_sendmsg net/socket.c:2503 [inline]
__x64_sys_sendmsg+0x42/0x50 net/socket.c:2503
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888168ad6410 of 8 bytes by task 13560 on cpu 0:
qdisc_lookup_rcu+0x30/0x2e0 net/sched/sch_api.c:323
__tcf_qdisc_find+0x74/0x3a0 net/sched/cls_api.c:1050
tc_del_tfilter+0x1c7/0x1350 net/sched/cls_api.c:2211
rtnetlink_rcv_msg+0x5ba/0x7e0 net/core/rtnetlink.c:5585
netlink_rcv_skb+0x14e/0x250 net/netlink/af_netlink.c:2494
rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5612
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x602/0x6d0 net/netlink/af_netlink.c:1343
netlink_sendmsg+0x728/0x850 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg net/socket.c:725 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2413
___sys_sendmsg net/socket.c:2467 [inline]
__sys_sendmsg+0x195/0x230 net/socket.c:2496
__do_sys_sendmsg net/socket.c:2505 [inline]
__se_sys_sendmsg net/socket.c:2503 [inline]
__x64_sys_sendmsg+0x42/0x50 net/socket.c:2503
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffffffff85dee080 -> 0xffff88815d96ec00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13560 Comm: syz-executor.2 Not tainted 5.17.0-rc3-syzkaller-00116-gf1baf68e1383-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: 470502de5bdb ("net: sched: unlock rules update API")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Vlad Buslov <vladbu@mellanox.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

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net_sched: restore "mpu xxx" handling

commit 56b765b79e9a ("htb: improved accuracy at high rates") broke
"overhead X", "linklayer atm" and "mpu X" attributes.

"overhead X" and "linklayer atm" have

net_sched: restore "mpu xxx" handling

commit 56b765b79e9a ("htb: improved accuracy at high rates") broke
"overhead X", "linklayer atm" and "mpu X" attributes.

"overhead X" and "linklayer atm" have already been fixed. This restores
the "mpu X" handling, as might be used by DOCSIS or Ethernet shaping:

tc class add ... htb rate X overhead 4 mpu 64

The code being fixed is used by htb, tbf and act_police. Cake has its
own mpu handling. qdisc_calculate_pkt_len still uses the size table
containing values adjusted for mpu by user space.

iproute2 tc has always passed mpu into the kernel via a tc_ratespec
structure, but the kernel never directly acted on it, merely stored it
so that it could be read back by `tc class show`.

Rather, tc would generate length-to-time tables that included the mpu
(and linklayer) in their construction, and the kernel used those tables.

Since v3.7, the tables were no longer used. Along with "mpu", this also
broke "overhead" and "linklayer" which were fixed in 01cb71d2d47b
("net_sched: restore "overhead xxx" handling", v3.10) and 8a8e3d84b171
("net_sched: restore "linklayer atm" handling", v3.11).

"overhead" was fixed by simply restoring use of tc_ratespec::overhead -
this had originally been used by the kernel but was initially omitted
from the new non-table-based calculations.

"linklayer" had been handled in the table like "mpu", but the mode was
not originally passed in tc_ratespec. The new implementation was made to
handle it by getting new versions of tc to pass the mode in an extended
tc_ratespec, and for older versions of tc the table contents were analysed
at load time to deduce linklayer.

As "mpu" has always been given to the kernel in tc_ratespec,
accompanying the mpu-based table, we can restore system functionality
with no userspace change by making the kernel act on the tc_ratespec
value.

Fixes: 56b765b79e9a ("htb: improved accuracy at high rates")
Signed-off-by: Kevin Bracey <kevin@bracey.fi>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: Vimalkumar <j.vimal@gmail.com>
Link: https://lore.kernel.org/r/20220112170210.1014351-1-kevin@bracey.fi
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: watchdog: add net device refcount tracker

Add a netdevice_tracker inside struct net_device, to track
the self reference when a device has an active watchdog timer.

Signed-off-by: Eric Dumazet

net: watchdog: add net device refcount tracker

Add a netdevice_tracker inside struct net_device, to track
the self reference when a device has an active watchdog timer.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

net/sched: add net device refcount tracker to struct Qdisc

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: no longer stop all TX queues in dev_watchdog()

There is no reason for stopping all TX queues from dev_watchdog()

Not only this stops feeding the NIC, it also migrates all qdiscs
to be serviced

net: no longer stop all TX queues in dev_watchdog()

There is no reason for stopping all TX queues from dev_watchdog()

Not only this stops feeding the NIC, it also migrates all qdiscs
to be serviced on the cpu calling netif_tx_unlock(), causing
a potential latency artifact.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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net: do not inline netif_tx_lock()/netif_tx_unlock()

These are not fast path, there is no point in inlining them.

Also provide netif_freeze_queues()/netif_unfreeze_queues()
so that we can use them

net: do not inline netif_tx_lock()/netif_tx_unlock()

These are not fast path, there is no point in inlining them.

Also provide netif_freeze_queues()/netif_unfreeze_queues()
so that we can use them from dev_watchdog() in the following patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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net: annotate accesses to queue->trans_start

In following patches, dev_watchdog() will no longer stop all queues.
It will read queue->trans_start locklessly.

Signed-off-by: Eric Dumazet <edumazet@g

net: annotate accesses to queue->trans_start

In following patches, dev_watchdog() will no longer stop all queues.
It will read queue->trans_start locklessly.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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net: use an atomic_long_t for queue->trans_timeout

tx_timeout_show() assumed dev_watchdog() would stop all
the queues, to fetch queue->trans_timeout under protection
of the queue->_xmit_lock.

As we

net: use an atomic_long_t for queue->trans_timeout

tx_timeout_show() assumed dev_watchdog() would stop all
the queues, to fetch queue->trans_timeout under protection
of the queue->_xmit_lock.

As we want to no longer disrupt transmits, we use an
atomic_long_t instead.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: david decotigny <david.decotigny@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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net: sch: simplify condtion for selecting mini_Qdisc_pair buffer

The only valid values for a miniq pointer are NULL or a pointer to
miniq1 or miniq2, so testing for miniq_old != &miniq1 is functiona

net: sch: simplify condtion for selecting mini_Qdisc_pair buffer

The only valid values for a miniq pointer are NULL or a pointer to
miniq1 or miniq2, so testing for miniq_old != &miniq1 is functionally
equivalent to testing that it is NULL or equal to &miniq2.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Seth Forshee <sforshee@digitalocean.com>
Link: https://lore.kernel.org/r/20211026183721.137930-1-seth@forshee.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: sch: eliminate unnecessary RCU waits in mini_qdisc_pair_swap()

Currently rcu_barrier() is used to ensure that no readers of the
inactive mini_Qdisc buffer remain before it is reused. This waits

net: sch: eliminate unnecessary RCU waits in mini_qdisc_pair_swap()

Currently rcu_barrier() is used to ensure that no readers of the
inactive mini_Qdisc buffer remain before it is reused. This waits for
any pending RCU callbacks to complete, when all that is actually
required is to wait for one RCU grace period to elapse after the buffer
was made inactive. This means that using rcu_barrier() may result in
unnecessary waits.

To improve this, store the current RCU state when a buffer is made
inactive and use poll_state_synchronize_rcu() to check whether a full
grace period has elapsed before reusing it. If a full grace period has
not elapsed, wait for a grace period to elapse, and in the non-RT case
use synchronize_rcu_expedited() to hasten it.

Since this approach eliminates the RCU callback it is no longer
necessary to synchronize_rcu() in the tp_head==NULL case. However, the
RCU state should still be saved for the previously active buffer.

Before this change I would typically see mini_qdisc_pair_swap() take
tens of milliseconds to complete. After this change it typcially
finishes in less than 1 ms, and often it takes just a few microseconds.

Thanks to Paul for walking me through the options for improving this.

Cc: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Seth Forshee <sforshee@digitalocean.com>
Link: https://lore.kernel.org/r/20211026130700.121189-1-seth@forshee.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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net: sched: Remove Qdisc::running sequence counter

The Qdisc::running sequence counter has two uses:

1. Reliably reading qdisc's tc statistics while the qdisc is running
(a seqcount read/ret

net: sched: Remove Qdisc::running sequence counter

The Qdisc::running sequence counter has two uses:

1. Reliably reading qdisc's tc statistics while the qdisc is running
(a seqcount read/retry loop at gnet_stats_add_basic()).

2. As a flag, indicating whether the qdisc in question is running
(without any retry loops).

For the first usage, the Qdisc::running sequence counter write section,
qdisc_run_begin() => qdisc_run_end(), covers a much wider area than what
is actually needed: the raw qdisc's bstats update. A u64_stats sync
point was thus introduced (in previous commits) inside the bstats
structure itself. A local u64_stats write section is then started and
stopped for the bstats updates.

Use that u64_stats sync point mechanism for the bstats read/retry loop
at gnet_stats_add_basic().

For the second qdisc->running usage, a __QDISC_STATE_RUNNING bit flag,
accessed with atomic bitops, is sufficient. Using a bit flag instead of
a sequence counter at qdisc_run_begin/end() and qdisc_is_running() leads
to the SMP barriers implicitly added through raw_read_seqcount() and
write_seqcount_begin/end() getting removed. All call sites have been
surveyed though, and no required ordering was identified.

Now that the qdisc->running sequence counter is no longer used, remove
it.

Note, using u64_stats implies no sequence counter protection for 64-bit
architectures. This can lead to the qdisc tc statistics "packets" vs.
"bytes" values getting out of sync on rare occasions. The individual
values will still be valid.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: sched: Merge Qdisc::bstats and Qdisc::cpu_bstats data types

The only factor differentiating per-CPU bstats data type (struct
gnet_stats_basic_cpu) from the packed non-per-CPU one (struct
gnet_s

net: sched: Merge Qdisc::bstats and Qdisc::cpu_bstats data types

The only factor differentiating per-CPU bstats data type (struct
gnet_stats_basic_cpu) from the packed non-per-CPU one (struct
gnet_stats_basic_packed) was a u64_stats sync point inside the former.
The two data types are now equivalent: earlier commits added a u64_stats
sync point to the latter.

Combine both data types into "struct gnet_stats_basic_sync". This
eliminates redundancy and simplifies the bstats read/write APIs.

Use u64_stats_t for bstats "packets" and "bytes" data types. On 64-bit
architectures, u64_stats sync points do not use sequence counter
protection.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: sched: Protect Qdisc::bstats with u64_stats

The not-per-CPU variant of qdisc tc (traffic control) statistics,
Qdisc::gnet_stats_basic_packed bstats, is protected with Qdisc::running
sequence co

net: sched: Protect Qdisc::bstats with u64_stats

The not-per-CPU variant of qdisc tc (traffic control) statistics,
Qdisc::gnet_stats_basic_packed bstats, is protected with Qdisc::running
sequence counter.

This sequence counter is used for reliably protecting bstats reads from
parallel writes. Meanwhile, the seqcount's write section covers a much
wider area than bstats update: qdisc_run_begin() => qdisc_run_end().

That read/write section asymmetry can lead to needless retries of the
read section. To prepare for removing the Qdisc::running sequence
counter altogether, introduce a u64_stats sync point inside bstats
instead.

Modify _bstats_update() to start/end the bstats u64_stats write
section.

For bisectability, and finer commits granularity, the bstats read
section is still protected with a Qdisc::running read/retry loop and
qdisc_run_begin/end() still starts/ends that seqcount write section.
Once all call sites are modified to use _bstats_update(), the
Qdisc::running seqcount will be removed and bstats read/retry loop will
be modified to utilize the internal u64_stats sync point.

Note, using u64_stats implies no sequence counter protection for 64-bit
architectures. This can lead to the statistics "packets" vs. "bytes"
values getting out of sync on rare occasions. The individual values will
still be valid.

[bigeasy: Minor commit message edits, init all gnet_stats_basic_packed.]

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: sched: move and reuse mq_change_real_num_tx()

The code for handling active queue changes is identical
between mq and mqprio, reuse it.

Suggested-by: Cong Wang <cong.wang@bytedance.com>
Signed-

net: sched: move and reuse mq_change_real_num_tx()

The code for handling active queue changes is identical
between mq and mqprio, reuse it.

Suggested-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...