linux-stable.git/net/core, branch v6.2.13

skbuff: Fix a race between coalescing and releasing SKBs

2023-04-20T10:36:55+00:00

[ Upstream commit 0646dc31ca886693274df5749cd0c8c1eaaeb5ca ]

Commit 1effe8ca4e34 ("skbuff: fix coalescing for page_pool fragment
recycling") allowed coalescing to proceed with non page pool page and page
pool page when @from is cloned, i.e.

to->pp_recycle    --> false
from->pp_recycle  --> true
skb_cloned(from)  --> true

However, it actually requires skb_cloned(@from) to hold true until
coalescing finishes in this situation. If the other cloned SKB is
released while the merging is in process, from_shinfo->nr_frags will be
set to 0 toward the end of the function, causing the increment of frag
page _refcount to be unexpectedly skipped resulting in inconsistent
reference counts. Later when SKB(@to) is released, it frees the page
directly even though the page pool page is still in use, leading to
use-after-free or double-free errors. So it should be prohibited.

The double-free error message below prompted us to investigate:
BUG: Bad page state in process swapper/1  pfn:0e0d1
page:00000000c6548b28 refcount:-1 mapcount:0 mapping:0000000000000000
index:0x2 pfn:0xe0d1
flags: 0xfffffc0000000(node=0|zone=1|lastcpupid=0x1fffff)
raw: 000fffffc0000000 0000000000000000 ffffffff00000101 0000000000000000
raw: 0000000000000002 0000000000000000 ffffffffffffffff 0000000000000000
page dumped because: nonzero _refcount

CPU: 1 PID: 0 Comm: swapper/1 Tainted: G            E      6.2.0+
Call Trace:
 
dump_stack_lvl+0x32/0x50
bad_page+0x69/0xf0
free_pcp_prepare+0x260/0x2f0
free_unref_page+0x20/0x1c0
skb_release_data+0x10b/0x1a0
napi_consume_skb+0x56/0x150
net_rx_action+0xf0/0x350
? __napi_schedule+0x79/0x90
__do_softirq+0xc8/0x2b1
__irq_exit_rcu+0xb9/0xf0
common_interrupt+0x82/0xa0


asm_common_interrupt+0x22/0x40
RIP: 0010:default_idle+0xb/0x20

Fixes: 53e0961da1c7 ("page_pool: add frag page recycling support in page pool")
Signed-off-by: Liang Chen 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20230413090353.14448-1-liangchen.linux@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

rtnetlink: Restore RTM_NEW/DELLINK notification behavior

2023-04-20T10:36:55+00:00

[ Upstream commit 59d3efd27c11c59b32291e5ebc307bed2edb65ee ]

The commits referenced below allows userspace to use the NLM_F_ECHO flag
for RTM_NEW/DELLINK operations to receive unicast notifications for the
affected link. Prior to these changes, applications may have relied on
multicast notifications to learn the same information without specifying
the NLM_F_ECHO flag.

For such applications, the mentioned commits changed the behavior for
requests not using NLM_F_ECHO. Multicast notifications are still received,
but now use the portid of the requester and the sequence number of the
request instead of zero values used previously. For the application, this
message may be unexpected and likely handled as a response to the
NLM_F_ACKed request, especially if it uses the same socket to handle
requests and notifications.

To fix existing applications relying on the old notification behavior,
set the portid and sequence number in the notification only if the
request included the NLM_F_ECHO flag. This restores the old behavior
for applications not using it, but allows unicasted notifications for
others.

Fixes: f3a63cce1b4f ("rtnetlink: Honour NLM_F_ECHO flag in rtnl_delete_link")
Fixes: d88e136cab37 ("rtnetlink: Honour NLM_F_ECHO flag in rtnl_newlink_create")
Signed-off-by: Martin Willi 
Acked-by: Guillaume Nault 
Acked-by: Hangbin Liu 
Link: https://lore.kernel.org/r/20230411074319.24133-1-martin@strongswan.org
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: openvswitch: fix race on port output

2023-04-20T10:36:54+00:00

[ Upstream commit 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 ]

assume the following setup on a single machine:
1. An openvswitch instance with one bridge and default flows
2. two network namespaces "server" and "client"
3. two ovs interfaces "server" and "client" on the bridge
4. for each ovs interface a veth pair with a matching name and 32 rx and
   tx queues
5. move the ends of the veth pairs to the respective network namespaces
6. assign ip addresses to each of the veth ends in the namespaces (needs
   to be the same subnet)
7. start some http server on the server network namespace
8. test if a client in the client namespace can reach the http server

when following the actions below the host has a chance of getting a cpu
stuck in a infinite loop:
1. send a large amount of parallel requests to the http server (around
   3000 curls should work)
2. in parallel delete the network namespace (do not delete interfaces or
   stop the server, just kill the namespace)

there is a low chance that this will cause the below kernel cpu stuck
message. If this does not happen just retry.
Below there is also the output of bpftrace for the functions mentioned
in the output.

The series of events happening here is:
1. the network namespace is deleted calling
   `unregister_netdevice_many_notify` somewhere in the process
2. this sets first `NETREG_UNREGISTERING` on both ends of the veth and
   then runs `synchronize_net`
3. it then calls `call_netdevice_notifiers` with `NETDEV_UNREGISTER`
4. this is then handled by `dp_device_event` which calls
   `ovs_netdev_detach_dev` (if a vport is found, which is the case for
   the veth interface attached to ovs)
5. this removes the rx_handlers of the device but does not prevent
   packages to be sent to the device
6. `dp_device_event` then queues the vport deletion to work in
   background as a ovs_lock is needed that we do not hold in the
   unregistration path
7. `unregister_netdevice_many_notify` continues to call
   `netdev_unregister_kobject` which sets `real_num_tx_queues` to 0
8. port deletion continues (but details are not relevant for this issue)
9. at some future point the background task deletes the vport

If after 7. but before 9. a packet is send to the ovs vport (which is
not deleted at this point in time) which forwards it to the
`dev_queue_xmit` flow even though the device is unregistering.
In `skb_tx_hash` (which is called in the `dev_queue_xmit`) path there is
a while loop (if the packet has a rx_queue recorded) that is infinite if
`dev->real_num_tx_queues` is zero.

To prevent this from happening we update `do_output` to handle devices
without carrier the same as if the device is not found (which would
be the code path after 9. is done).

Additionally we now produce a warning in `skb_tx_hash` if we will hit
the infinite loop.

bpftrace (first word is function name):

__dev_queue_xmit server: real_num_tx_queues: 1, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 1
netdev_core_pick_tx server: addr: 0xffff9f0a46d4a000 real_num_tx_queues: 1, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 1
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 2, reg_state: 1
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 6, reg_state: 2
ovs_netdev_detach_dev server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, reg_state: 2
netdev_rx_handler_unregister server: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024, reg_state: 2
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
netdev_rx_handler_unregister ret server: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024, reg_state: 2
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 27, reg_state: 2
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 22, reg_state: 2
dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 18, reg_state: 2
netdev_unregister_kobject: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024
synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
ovs_vport_send server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
__dev_queue_xmit server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
netdev_core_pick_tx server: addr: 0xffff9f0a46d4a000 real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
broken device server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024
ovs_dp_detach_port server: real_num_tx_queues: 0 cpu 9, pid: 9124, tid: 9124, reg_state: 2
synchronize_rcu_expedited: cpu 9, pid: 33604, tid: 33604

stuck message:

watchdog: BUG: soft lockup - CPU#5 stuck for 26s! [curl:1929279]
Modules linked in: veth pktgen bridge stp llc ip_set_hash_net nft_counter xt_set nft_compat nf_tables ip_set_hash_ip ip_set nfnetlink_cttimeout nfnetlink openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 tls binfmt_misc nls_iso8859_1 input_leds joydev serio_raw dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua sch_fq_codel drm efi_pstore virtio_rng ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel virtio_net ahci net_failover crypto_simd cryptd psmouse libahci virtio_blk failover
CPU: 5 PID: 1929279 Comm: curl Not tainted 5.15.0-67-generic #74-Ubuntu
Hardware name: OpenStack Foundation OpenStack Nova, BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:netdev_pick_tx+0xf1/0x320
Code: 00 00 8d 48 ff 0f b7 c1 66 39 ca 0f 86 e9 01 00 00 45 0f b7 ff 41 39 c7 0f 87 5b 01 00 00 44 29 f8 41 39 c7 0f 87 4f 01 00 00  f2 0f 1f 44 00 00 49 8b 94 24 28 04 00 00 48 85 d2 0f 84 53 01
RSP: 0018:ffffb78b40298820 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff9c8773adc2e0 RCX: 000000000000083f
RDX: 0000000000000000 RSI: ffff9c8773adc2e0 RDI: ffff9c870a25e000
RBP: ffffb78b40298858 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff9c870a25e000
R13: ffff9c870a25e000 R14: ffff9c87fe043480 R15: 0000000000000000
FS:  00007f7b80008f00(0000) GS:ffff9c8e5f740000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7b80f6a0b0 CR3: 0000000329d66000 CR4: 0000000000350ee0
Call Trace:
 
 netdev_core_pick_tx+0xa4/0xb0
 __dev_queue_xmit+0xf8/0x510
 ? __bpf_prog_exit+0x1e/0x30
 dev_queue_xmit+0x10/0x20
 ovs_vport_send+0xad/0x170 [openvswitch]
 do_output+0x59/0x180 [openvswitch]
 do_execute_actions+0xa80/0xaa0 [openvswitch]
 ? kfree+0x1/0x250
 ? kfree+0x1/0x250
 ? kprobe_perf_func+0x4f/0x2b0
 ? flow_lookup.constprop.0+0x5c/0x110 [openvswitch]
 ovs_execute_actions+0x4c/0x120 [openvswitch]
 ovs_dp_process_packet+0xa1/0x200 [openvswitch]
 ? ovs_ct_update_key.isra.0+0xa8/0x120 [openvswitch]
 ? ovs_ct_fill_key+0x1d/0x30 [openvswitch]
 ? ovs_flow_key_extract+0x2db/0x350 [openvswitch]
 ovs_vport_receive+0x77/0xd0 [openvswitch]
 ? __htab_map_lookup_elem+0x4e/0x60
 ? bpf_prog_680e8aff8547aec1_kfree+0x3b/0x714
 ? trace_call_bpf+0xc8/0x150
 ? kfree+0x1/0x250
 ? kfree+0x1/0x250
 ? kprobe_perf_func+0x4f/0x2b0
 ? kprobe_perf_func+0x4f/0x2b0
 ? __mod_memcg_lruvec_state+0x63/0xe0
 netdev_port_receive+0xc4/0x180 [openvswitch]
 ? netdev_port_receive+0x180/0x180 [openvswitch]
 netdev_frame_hook+0x1f/0x40 [openvswitch]
 __netif_receive_skb_core.constprop.0+0x23d/0xf00
 __netif_receive_skb_one_core+0x3f/0xa0
 __netif_receive_skb+0x15/0x60
 process_backlog+0x9e/0x170
 __napi_poll+0x33/0x180
 net_rx_action+0x126/0x280
 ? ttwu_do_activate+0x72/0xf0
 __do_softirq+0xd9/0x2e7
 ? rcu_report_exp_cpu_mult+0x1b0/0x1b0
 do_softirq+0x7d/0xb0
 
 
 __local_bh_enable_ip+0x54/0x60
 ip_finish_output2+0x191/0x460
 __ip_finish_output+0xb7/0x180
 ip_finish_output+0x2e/0xc0
 ip_output+0x78/0x100
 ? __ip_finish_output+0x180/0x180
 ip_local_out+0x5e/0x70
 __ip_queue_xmit+0x184/0x440
 ? tcp_syn_options+0x1f9/0x300
 ip_queue_xmit+0x15/0x20
 __tcp_transmit_skb+0x910/0x9c0
 ? __mod_memcg_state+0x44/0xa0
 tcp_connect+0x437/0x4e0
 ? ktime_get_with_offset+0x60/0xf0
 tcp_v4_connect+0x436/0x530
 __inet_stream_connect+0xd4/0x3a0
 ? kprobe_perf_func+0x4f/0x2b0
 ? aa_sk_perm+0x43/0x1c0
 inet_stream_connect+0x3b/0x60
 __sys_connect_file+0x63/0x70
 __sys_connect+0xa6/0xd0
 ? setfl+0x108/0x170
 ? do_fcntl+0xe8/0x5a0
 __x64_sys_connect+0x18/0x20
 do_syscall_64+0x5c/0xc0
 ? __x64_sys_fcntl+0xa9/0xd0
 ? exit_to_user_mode_prepare+0x37/0xb0
 ? syscall_exit_to_user_mode+0x27/0x50
 ? do_syscall_64+0x69/0xc0
 ? __sys_setsockopt+0xea/0x1e0
 ? exit_to_user_mode_prepare+0x37/0xb0
 ? syscall_exit_to_user_mode+0x27/0x50
 ? __x64_sys_setsockopt+0x1f/0x30
 ? do_syscall_64+0x69/0xc0
 ? irqentry_exit+0x1d/0x30
 ? exc_page_fault+0x89/0x170
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7b8101c6a7
Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 18 89 54 24 0c 48 89 34 24 89
RSP: 002b:00007ffffd6b2198 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7b8101c6a7
RDX: 0000000000000010 RSI: 00007ffffd6b2360 RDI: 0000000000000005
RBP: 0000561f1370d560 R08: 00002795ad21d1ac R09: 0030312e302e302e
R10: 00007ffffd73f080 R11: 0000000000000246 R12: 0000561f1370c410
R13: 0000000000000000 R14: 0000000000000005 R15: 0000000000000000
 

Fixes: 7f8a436eaa2c ("openvswitch: Add conntrack action")
Co-developed-by: Luca Czesla 
Signed-off-by: Luca Czesla 
Signed-off-by: Felix Huettner 
Reviewed-by: Eric Dumazet 
Reviewed-by: Simon Horman 
Link: https://lore.kernel.org/r/ZC0pBXBAgh7c76CA@kernel-bug-kernel-bug
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: don't let netpoll invoke NAPI if in xmit context

2023-04-13T15:02:38+00:00

[ Upstream commit 275b471e3d2daf1472ae8fa70dc1b50c9e0b9e75 ]

Commit 0db3dc73f7a3 ("[NETPOLL]: tx lock deadlock fix") narrowed
down the region under netif_tx_trylock() inside netpoll_send_skb().
(At that point in time netif_tx_trylock() would lock all queues of
the device.) Taking the tx lock was problematic because driver's
cleanup method may take the same lock. So the change made us hold
the xmit lock only around xmit, and expected the driver to take
care of locking within ->ndo_poll_controller().

Unfortunately this only works if netpoll isn't itself called with
the xmit lock already held. Netpoll code is careful and uses
trylock(). The drivers, however, may be using plain lock().
Printing while holding the xmit lock is going to result in rare
deadlocks.

Luckily we record the xmit lock owners, so we can scan all the queues,
the same way we scan NAPI owners. If any of the xmit locks is held
by the local CPU we better not attempt any polling.

It would be nice if we could narrow down the check to only the NAPIs
and the queue we're trying to use. I don't see a way to do that now.

Reported-by: Roman Gushchin 
Fixes: 0db3dc73f7a3 ("[NETPOLL]: tx lock deadlock fix")
Signed-off-by: Jakub Kicinski 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

net: use indirect calls helpers for sk_exit_memory_pressure()

2023-03-17T07:57:53+00:00

[ Upstream commit 5c1ebbfabcd61142a4551bfc0e51840f9bdae7af ]

Florian reported a regression and sent a patch with the following
changelog:


 There is a noticeable tcp performance regression (loopback or cross-netns),
 seen with iperf3 -Z (sendfile mode) when generic retpolines are needed.

 With SK_RECLAIM_THRESHOLD checks gone number of calls to enter/leave
 memory pressure happen much more often. For TCP indirect calls are
 used.

 We can't remove the if-set-return short-circuit check in
 tcp_enter_memory_pressure because there are callers other than
 sk_enter_memory_pressure.  Doing a check in the sk wrapper too
 reduces the indirect calls enough to recover some performance.

 Before,
 0.00-60.00  sec   322 GBytes  46.1 Gbits/sec                  receiver

 After:
 0.00-60.04  sec   359 GBytes  51.4 Gbits/sec                  receiver

 "iperf3 -c $peer -t 60 -Z -f g", connected via veth in another netns.


It seems we forgot to upstream this indirect call mitigation we
had for years, lets do this instead.

[edumazet] - It seems we forgot to upstream this indirect call
             mitigation we had for years, let's do this instead.
           - Changed to INDIRECT_CALL_INET_1() to avoid bots reports.

Fixes: 4890b686f408 ("net: keep sk->sk_forward_alloc as small as possible")
Reported-by: Florian Westphal 
Link: https://lore.kernel.org/netdev/20230227152741.4a53634b@kernel.org/T/
Signed-off-by: Brian Vazquez 
Signed-off-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20230301133247.2346111-1-edumazet@google.com
Signed-off-by: Paolo Abeni 
Signed-off-by: Sasha Levin

net: fix __dev_kfree_skb_any() vs drop monitor

2023-03-11T12:50:31+00:00

[ Upstream commit ac3ad19584b26fae9ac86e4faebe790becc74491 ]

dev_kfree_skb() is aliased to consume_skb().

When a driver is dropping a packet by calling dev_kfree_skb_any()
we should propagate the drop reason instead of pretending
the packet was consumed.

Note: Now we have enum skb_drop_reason we could remove
enum skb_free_reason (for linux-6.4)

v2: added an unlikely(), suggested by Yunsheng Lin.

Fixes: e6247027e517 ("net: introduce dev_consume_skb_any()")
Signed-off-by: Eric Dumazet 
Cc: Yunsheng Lin 
Reviewed-by: Yunsheng Lin 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

scm: add user copy checks to put_cmsg()

2023-03-10T08:29:13+00:00

[ Upstream commit 5f1eb1ff58ea122e24adf0bc940f268ed2227462 ]

This is a followup of commit 2558b8039d05 ("net: use a bounce
buffer for copying skb->mark")

x86 and powerpc define user_access_begin, meaning
that they are not able to perform user copy checks
when using user_write_access_begin() / unsafe_copy_to_user()
and friends [1]

Instead of waiting bugs to trigger on other arches,
add a check_object_size() in put_cmsg() to make sure
that new code tested on x86 with CONFIG_HARDENED_USERCOPY=y
will perform more security checks.

[1] We can not generically call check_object_size() from
unsafe_copy_to_user() because UACCESS is enabled at this point.

Signed-off-by: Eric Dumazet 
Cc: Kees Cook 
Acked-by: Kees Cook 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

net: add sock_init_data_uid()

2023-03-10T08:28:16+00:00

[ Upstream commit 584f3742890e966d2f0a1f3c418c9ead70b2d99e ]

Add sock_init_data_uid() to explicitly initialize the socket uid.
To initialise the socket uid, sock_init_data() assumes a the struct
socket* sock is always embedded in a struct socket_alloc, used to
access the corresponding inode uid. This may not be true.
Examples are sockets created in tun_chr_open() and tap_open().

Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.")
Signed-off-by: Pietro Borrello 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

bpf: bpf_fib_lookup should not return neigh in NUD_FAILED state

2023-03-03T10:56:16+00:00

commit 1fe4850b34ab512ff911e2c035c75fb6438f7307 upstream.

The bpf_fib_lookup() helper does not only look up the fib (ie. route)
but it also looks up the neigh. Before returning the neigh, the helper
does not check for NUD_VALID. When a neigh state (neigh->nud_state)
is in NUD_FAILED, its dmac (neigh->ha) could be all zeros. The helper
still returns SUCCESS instead of NO_NEIGH in this case. Because of the
SUCCESS return value, the bpf prog directly uses the returned dmac
and ends up filling all zero in the eth header.

This patch checks for NUD_VALID and returns NO_NEIGH if the neigh is
not valid.

Signed-off-by: Martin KaFai Lau 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20230217004150.2980689-3-martin.lau@linux.dev
Signed-off-by: Greg Kroah-Hartman

devlink: Fix netdev notifier chain corruption

2023-02-16T10:53:47+00:00

Cited commit changed devlink to register its netdev notifier block on
the global netdev notifier chain instead of on the per network namespace
one.

However, when changing the network namespace of the devlink instance,
devlink still tries to unregister its notifier block from the chain of
the old namespace and register it on the chain of the new namespace.
This results in corruption of the notifier chains, as the same notifier
block is registered on two different chains: The global one and the per
network namespace one. In turn, this causes other problems such as the
inability to dismantle namespaces due to netdev reference count issues.

Fix by preventing devlink from moving its notifier block between
namespaces.

Reproducer:

 # echo "10 1" > /sys/bus/netdevsim/new_device
 # ip netns add test123
 # devlink dev reload netdevsim/netdevsim10 netns test123
 # ip netns del test123
 [   71.935619] unregister_netdevice: waiting for lo to become free. Usage count = 2
 [   71.938348] leaked reference.

Fixes: 565b4824c39f ("devlink: change port event netdev notifier from per-net to global")
Signed-off-by: Ido Schimmel 
Reviewed-by: Jiri Pirko 
Reviewed-by: Jacob Keller 
Reviewed-by: Jakub Kicinski 
Link: https://lore.kernel.org/r/20230215073139.1360108-1-idosch@nvidia.com
Signed-off-by: Paolo Abeni