When a SOCK_(STREAM|SEQPACKET) socket connect()s to another one, we need
to lock the two sockets to check their states in unix_stream_connect().

We use unix_state_lock() for the server and unix_state_lock_nested() for
client with tricky sk->sk_state check to avoid deadlock.

The possible deadlock scenario are the following:

  1) Self connect()
  2) Simultaneous connect()

The former is simple, attempt to grab the same lock, and the latter is
AB-BA deadlock.

After the server's unix_state_lock(), we check the server socket's state,
and if it's not TCP_LISTEN, connect() fails with -EINVAL.

Then, we avoid the former deadlock by checking the client's state before
unix_state_lock_nested().  If its state is not TCP_LISTEN, we can make
sure that the client and the server are not identical based on the state.

Also, the latter deadlock can be avoided in the same way.  Due to the
server sk->sk_state requirement, AB-BA deadlock could happen only with
TCP_LISTEN sockets.  So, if the client's state is TCP_LISTEN, we can
give up the second lock to avoid the deadlock.

  CPU 1                 CPU 2                  CPU 3
  connect(A -> B)       connect(B -> A)        listen(A)
  ---                   ---                    ---
  unix_state_lock(B)
  B->sk_state == TCP_LISTEN
  READ_ONCE(A->sk_state) == TCP_CLOSE
                            ^^^^^^^^^
                            ok, will lock A    unix_state_lock(A)
             .--------------'                  WRITE_ONCE(A->sk_state, TCP_LISTEN)
             |                                 unix_state_unlock(A)
             |
             |          unix_state_lock(A)
             |          A->sk_sk_state == TCP_LISTEN
             |          READ_ONCE(B->sk_state) == TCP_LISTEN
             v                                    ^^^^^^^^^^
  unix_state_lock_nested(A)                       Don't lock B !!

Currently, while checking the client's state, we also check if it's
TCP_ESTABLISHED, but this is unlikely and can be checked after we know
the state is not TCP_CLOSE.

Moreover, if it happens after the second lock, we now jump to the restart
label, but it's unlikely that the server is not found during the retry,
so the jump is mostly to revist the client state check.

Let's remove the retry logic and check the state against TCP_CLOSE first.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

unix_dgram_connect() and unix_dgram_{send,recv}msg() lock the socket
and peer in ascending order of the socket address.

Let's define the order as unix_state_lock_cmp_fn() instead of using
unix_state_lock_nested().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

When created, AF_UNIX socket is put into net->unx.table.buckets[],
and the hash is stored in sk->sk_hash.

  * unbound socket  : 0 <= sk_hash <= UNIX_HASH_MOD

When bind() is called, the socket could be moved to another bucket.

  * pathname socket : 0 <= sk_hash <= UNIX_HASH_MOD
  * abstract socket : UNIX_HASH_MOD + 1 <= sk_hash <= UNIX_HASH_MOD * 2 + 1

Then, we call unix_table_double_lock() which locks a single bucket
or two.

Let's define the order as unix_table_lock_cmp_fn() instead of using
spin_lock_nested().

The locking is always done in ascending order of sk->sk_hash, which
is the index of buckets/locks array allocated by kvmalloc_array().

  sk_hash_A < sk_hash_B
  <=> &locks[sk_hash_A].dep_map < &locks[sk_hash_B].dep_map

So, the relation of two sk->sk_hash can be derived from the addresses
of dep_map in the array of locks.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Sebastian Andrzej Siewior says:

====================
locking: Introduce nested-BH locking.

Disabling bottoms halves acts as per-CPU BKL. On PREEMPT_RT code within
local_bh_disable() section remains preemtible. As a result high prior
tasks (or threaded interrupts) will be blocked by lower-prio task (or
threaded interrupts) which are long running which includes softirq
sections.

The proposed way out is to introduce explicit per-CPU locks for
resources which are protected by local_bh_disable() and use those only
on PREEMPT_RT so there is no additional overhead for !PREEMPT_RT builds.

The series introduces the infrastructure and converts large parts of
networking which is largest stake holder here. Once this done the
per-CPU lock from local_bh_disable() on PREEMPT_RT can be lifted.

Performance testing. Baseline is net-next as of commit 93bda330
("Merge branch'net-constify-ctl_table-arguments-of-utility-functions'")
plus v6.10-rc1. A 10GiG link is used between two hosts. The command
   xdp-bench redirect-cpu --cpu 3 --remote-action drop eth1 -e

was invoked on the receiving side with a ixgbe. The sending side uses
pktgen_sample03_burst_single_flow.sh on i40e.

Baseline:
| eth1->?                 9,018,604 rx/s                  0 err,drop/s
|   receive total         9,018,604 pkt/s                 0 drop/s                0 error/s
|     cpu:7               9,018,604 pkt/s                 0 drop/s                0 error/s
|   enqueue to cpu 3      9,018,602 pkt/s                 0 drop/s             7.00 bulk-avg
|     cpu:7->3            9,018,602 pkt/s                 0 drop/s             7.00 bulk-avg
|   kthread total         9,018,606 pkt/s                 0 drop/s          214,698 sched
|     cpu:3               9,018,606 pkt/s                 0 drop/s          214,698 sched
|     xdp_stats                   0 pass/s        9,018,606 drop/s                0 redir/s
|       cpu:3                     0 pass/s        9,018,606 drop/s                0 redir/s
|   redirect_err                  0 error/s
|   xdp_exception                 0 hit/s

perf top --sort cpu,symbol --no-children:
|   18.14%  007  [k] bpf_prog_4f0ffbb35139c187_cpumap_l4_hash
|   13.29%  007  [k] ixgbe_poll
|   12.66%  003  [k] cpu_map_kthread_run
|    7.23%  003  [k] page_frag_free
|    6.76%  007  [k] xdp_do_redirect
|    3.76%  007  [k] cpu_map_redirect
|    3.13%  007  [k] bq_flush_to_queue
|    2.51%  003  [k] xdp_return_frame
|    1.93%  007  [k] try_to_wake_up
|    1.78%  007  [k] _raw_spin_lock
|    1.74%  007  [k] cpu_map_enqueue
|    1.56%  003  [k] bpf_prog_57cd311f2e27366b_cpumap_drop

With this series applied:
| eth1->?                10,329,340 rx/s                  0 err,drop/s
|   receive total        10,329,340 pkt/s                 0 drop/s                0 error/s
|     cpu:6              10,329,340 pkt/s                 0 drop/s                0 error/s
|   enqueue to cpu 3     10,329,338 pkt/s                 0 drop/s             8.00 bulk-avg
|     cpu:6->3           10,329,338 pkt/s                 0 drop/s             8.00 bulk-avg
|   kthread total        10,329,321 pkt/s                 0 drop/s           96,297 sched
|     cpu:3              10,329,321 pkt/s                 0 drop/s           96,297 sched
|     xdp_stats                   0 pass/s       10,329,321 drop/s                0 redir/s
|       cpu:3                     0 pass/s       10,329,321 drop/s                0 redir/s
|   redirect_err                  0 error/s
|   xdp_exception                 0 hit/s

perf top --sort cpu,symbol --no-children:
|   20.90%  006  [k] bpf_prog_4f0ffbb35139c187_cpumap_l4_hash
|   12.62%  006  [k] ixgbe_poll
|    9.82%  003  [k] page_frag_free
|    8.73%  003  [k] cpu_map_bpf_prog_run_xdp
|    6.63%  006  [k] xdp_do_redirect
|    4.94%  003  [k] cpu_map_kthread_run
|    4.28%  006  [k] cpu_map_redirect
|    4.03%  006  [k] bq_flush_to_queue
|    3.01%  003  [k] xdp_return_frame
|    1.95%  006  [k] _raw_spin_lock
|    1.94%  003  [k] bpf_prog_57cd311f2e27366b_cpumap_drop

This diff appears to be noise.

v8: https://lore.kernel.org/all/20240619072253.504963-1-bigeasy@linutronix.de
v7: https://lore.kernel.org/all/20240618072526.379909-1-bigeasy@linutronix.de
v6: https://lore.kernel.org/all/20240612170303.3896084-1-bigeasy@linutronix.de
v5: https://lore.kernel.org/all/20240607070427.1379327-1-bigeasy@linutronix.de
v4: https://lore.kernel.org/all/20240604154425.878636-1-bigeasy@linutronix.de
v3: https://lore.kernel.org/all/20240529162927.403425-1-bigeasy@linutronix.de
v2: https://lore.kernel.org/all/20240503182957.1042122-1-bigeasy@linutronix.de
v1: https://lore.kernel.org/all/20231215171020.687342-1-bigeasy@linutronix.de
====================

Link: https://patch.msgid.link/20240620132727.660738-1-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The per-CPU flush lists, which are accessed from within the NAPI callback
(xdp_do_flush() for instance), are per-CPU. There are subject to the
same problem as struct bpf_redirect_info.

Add the per-CPU lists cpu_map_flush_list, dev_map_flush_list and
xskmap_map_flush_list to struct bpf_net_context. Add wrappers for the
access. The lists initialized on first usage (similar to
bpf_net_ctx_get_ri()).

Cc: "Björn Töpel" <bjorn@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jonathan Lemon <jonathan.lemon@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@intel.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-16-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The XDP redirect process is two staged:
- bpf_prog_run_xdp() is invoked to run a eBPF program which inspects the
  packet and makes decisions. While doing that, the per-CPU variable
  bpf_redirect_info is used.

- Afterwards xdp_do_redirect() is invoked and accesses bpf_redirect_info
  and it may also access other per-CPU variables like xskmap_flush_list.

At the very end of the NAPI callback, xdp_do_flush() is invoked which
does not access bpf_redirect_info but will touch the individual per-CPU
lists.

The per-CPU variables are only used in the NAPI callback hence disabling
bottom halves is the only protection mechanism. Users from preemptible
context (like cpu_map_kthread_run()) explicitly disable bottom halves
for protections reasons.
Without locking in local_bh_disable() on PREEMPT_RT this data structure
requires explicit locking.

PREEMPT_RT has forced-threaded interrupts enabled and every
NAPI-callback runs in a thread. If each thread has its own data
structure then locking can be avoided.

Create a struct bpf_net_context which contains struct bpf_redirect_info.
Define the variable on stack, use bpf_net_ctx_set() to save a pointer to
it, bpf_net_ctx_clear() removes it again.
The bpf_net_ctx_set() may nest. For instance a function can be used from
within NET_RX_SOFTIRQ/ net_rx_action which uses bpf_net_ctx_set() and
NET_TX_SOFTIRQ which does not. Therefore only the first invocations
updates the pointer.
Use bpf_net_ctx_get_ri() as a wrapper to retrieve the current struct
bpf_redirect_info. The returned data structure is zero initialized to
ensure nothing is leaked from stack. This is done on first usage of the
struct. bpf_net_ctx_set() sets bpf_redirect_info::kern_flags to 0 to
note that initialisation is required. First invocation of
bpf_net_ctx_get_ri() will memset() the data structure and update
bpf_redirect_info::kern_flags.
bpf_redirect_info::nh is excluded from memset because it is only used
once BPF_F_NEIGH is set which also sets the nh member. The kern_flags is
moved past nh to exclude it from memset.

The pointer to bpf_net_context is saved task's task_struct. Using
always the bpf_net_context approach has the advantage that there is
almost zero differences between PREEMPT_RT and non-PREEMPT_RT builds.

Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-15-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

bpf_scratchpad is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.

Add a local_lock_t to the data structure and use local_lock_nested_bh()
for locking. This change adds only lockdep coverage and does not alter
the functional behaviour for !PREEMPT_RT.

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-14-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The access to seg6_bpf_srh_states is protected by disabling preemption.
Based on the code, the entry point is input_action_end_bpf() and
every other function (the bpf helper functions bpf_lwt_seg6_*()), that
is accessing seg6_bpf_srh_states, should be called from within
input_action_end_bpf().

input_action_end_bpf() accesses seg6_bpf_srh_states first at the top of
the function and then disables preemption. This looks wrong because if
preemption needs to be disabled as part of the locking mechanism then
the variable shouldn't be accessed beforehand.

Looking at how it is used via test_lwt_seg6local.sh then
input_action_end_bpf() is always invoked from softirq context. If this
is always the case then the preempt_disable() statement is superfluous.
If this is not always invoked from softirq then disabling only
preemption is not sufficient.

Replace the preempt_disable() statement with nested-BH locking. This is
not an equivalent replacement as it assumes that the invocation of
input_action_end_bpf() always occurs in softirq context and thus the
preempt_disable() is superfluous.
Add a local_lock_t the data structure and use local_lock_nested_bh() for
locking. Add lockdep_assert_held() to ensure the lock is held while the
per-CPU variable is referenced in the helper functions.

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: David Ahern <dsahern@kernel.org>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-13-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

There is no need to explicitly disable migration if bottom halves are
also disabled. Disabling BH implies disabling migration.

Remove migrate_disable() and rely solely on disabling BH to remain on
the same CPU.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-12-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

softnet_data::process_queue is a per-CPU variable and relies on disabled
BH for its locking. Without per-CPU locking in local_bh_disable() on
PREEMPT_RT this data structure requires explicit locking.

softnet_data::input_queue_head can be updated lockless. This is fine
because this value is only update CPU local by the local backlog_napi
thread.

Add a local_lock_t to softnet_data and use local_lock_nested_bh() for locking
of process_queue. This change adds only lockdep coverage and does not
alter the functional behaviour for !PREEMPT_RT.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-11-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The backlog_napi locking (previously RPS) relies on explicit locking if
either RPS or backlog NAPI is enabled. If both are disabled then locking
was achieved by disabling interrupts except on PREEMPT_RT. PREEMPT_RT
was excluded because the needed synchronisation was already provided
local_bh_disable().

Since the introduction of backlog NAPI and making it mandatory for
PREEMPT_RT the ifdef within backlog_lock.*() is obsolete and can be
removed.

Remove the ifdefs in backlog_lock.*().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-10-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Softirq is preemptible on PREEMPT_RT. Without a per-CPU lock in
local_bh_disable() there is no guarantee that only one device is
transmitting at a time.
With preemption and multiple senders it is possible that the per-CPU
`recursion' counter gets incremented by different threads and exceeds
XMIT_RECURSION_LIMIT leading to a false positive recursion alert.
The `more' member is subject to similar problems if set by one thread
for one driver and wrongly used by another driver within another thread.

Instead of adding a lock to protect the per-CPU variable it is simpler
to make xmit per-task. Sending and receiving skbs happens always
in thread context anyway.

Having a lock to protected the per-CPU counter would block/ serialize two
sending threads needlessly. It would also require a recursive lock to
ensure that the owner can increment the counter further.

Make the softnet_data.xmit a task_struct member on PREEMPT_RT. Add
needed wrapper.

Cc: Ben Segall <bsegall@google.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-9-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

brnf_frag_data_storage is a per-CPU variable and relies on disabled BH
for its locking. Without per-CPU locking in local_bh_disable() on
PREEMPT_RT this data structure requires explicit locking.

Add a local_lock_t to the data structure and use local_lock_nested_bh()
for locking. This change adds only lockdep coverage and does not alter
the functional behaviour for !PREEMPT_RT.

Cc: Florian Westphal <fw@strlen.de>
Cc: Jozsef Kadlecsik <kadlec@netfilter.org>
Cc: Nikolay Aleksandrov <razor@blackwall.org>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Roopa Prabhu <roopa@nvidia.com>
Cc: bridge@lists.linux.dev
Cc: coreteam@netfilter.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-8-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

ipv4_tcp_sk is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.

Make a struct with a sock member (original ipv4_tcp_sk) and a
local_lock_t and use local_lock_nested_bh() for locking. This change
adds only lockdep coverage and does not alter the functional behaviour
for !PREEMPT_RT.

Cc: David Ahern <dsahern@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-7-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

sigpool_scratch is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.

Make a struct with a pad member (original sigpool_scratch) and a
local_lock_t and use local_lock_nested_bh() for locking. This change
adds only lockdep coverage and does not alter the functional behaviour
for !PREEMPT_RT.

Cc: David Ahern <dsahern@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-6-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

napi_alloc_cache is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.

Add a local_lock_t to the data structure and use local_lock_nested_bh()
for locking. This change adds only lockdep coverage and does not alter
the functional behaviour for !PREEMPT_RT.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-5-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The else condition within __netdev_alloc_frag_align() is an open coded
__napi_alloc_frag_align().

Use __napi_alloc_frag_align() instead of open coding it.
Move fragsz assignment before page_frag_alloc_align() invocation because
__napi_alloc_frag_align() also contains this statement.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-4-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Add local_lock_nested_bh() locking. It is based on local_lock_t and the
naming follows the preempt_disable_nested() example.

For !PREEMPT_RT + !LOCKDEP it is a per-CPU annotation for locking
assumptions based on local_bh_disable(). The macro is optimized away
during compilation.
For !PREEMPT_RT + LOCKDEP the local_lock_nested_bh() is reduced to
the usual lock-acquire plus lockdep_assert_in_softirq() - ensuring that
BH is disabled.

For PREEMPT_RT local_lock_nested_bh() acquires the specified per-CPU
lock. It does not disable CPU migration because it relies on
local_bh_disable() disabling CPU migration.
With LOCKDEP it performans the usual lockdep checks as with !PREEMPT_RT.
Due to include hell the softirq check has been moved spinlock.c.

The intention is to use this locking in places where locking of a per-CPU
variable relies on BH being disabled. Instead of treating disabled
bottom halves as a big per-CPU lock, PREEMPT_RT can use this to reduce
the locking scope to what actually needs protecting.
A side effect is that it also documents the protection scope of the
per-CPU variables.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-3-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Introduce lock guard definition for local_lock_t. There are no users
yet.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-2-bigeasy@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Commit 243996d1 ("dt-bindings: net: Convert fsl-fman to yaml") splits
the previous dt text file into four yaml files. It adjusts a corresponding
file entry in MAINTAINERS from txt to yaml, but this adjustment misses
that the file was split and renamed.

Hence, ./scripts/get_maintainer.pl --self-test=patterns complains about a
broken reference.

Adjust the file entry to match the four yaml files resulting from this
commit above.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Tony Nguyen says:

====================
ice: prepare representor for SF support

Michal Swiatkowski says:

This is a series to prepare port representor for supporting also
subfunctions. We need correct devlink locking and the possibility to
update parent VSI after port representor is created.

Refactor how devlink lock is taken to suite the subfunction use case.

VSI configuration needs to be done after port representor is created.
Port representor needs only allocated VSI. It doesn't need to be
configured before.

VSI needs to be reconfigured when update function is called.

The code for this patchset was split from (too big) patchset [1].

[1] https://lore.kernel.org/netdev/20240213072724.77275-1-michal.swiatkowski@linux.intel.com/
---
Originally from https://lore.kernel.org/netdev/20240605-next-2024-06-03-intel-next-batch-v2-0-39c23963fa78@intel.com/
Changes:
- delete ice_repr_get_by_vsi() from header
- rephrase commit message in moving devlink locking
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

We support multicast addresses, so enable it by default.
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'linux-can-next-for-6.11-20240621' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next

Marc Kleine-Budde says:

====================
pull-request: can-next 2024-06-21

The first 2 patches are by Andy Shevchenko, one cleans up the includes
in the mcp251x driver, the other one updates the sja100 plx_pci driver
to make use of predefines PCI subvendor ID.

Mans Rullgard's patch cleans up the Kconfig help text of for the slcan
driver.

Oliver Hartkopp provides a patch to update the documentation, which
removes the ISO 15675-2 specification version where possible.

The next 2 patches are by Harini T and update the documentation of the
xilinx_can driver.

Francesco Valla provides documentation for the ISO 15765-2 protocol.

A patch by Dr. David Alan Gilbert removes an unused struct from the
mscan driver.

12 patches are by Martin Jocic. The first three add support for 3 new
devices to the kvaser_usb driver. The remaining 9 first clean up the
kvaser_pciefd driver, and then add support for MSI.

Krzysztof Kozlowski contributes 3 patches simplifies the CAN SPI
drivers by making use of spi_get_device_match_data().

The last patch is by Martin Hundebøll, which reworks the m_can driver
to not enable the CAN transceiver during probe.

* tag 'linux-can-next-for-6.11-20240621' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next: (24 commits)
  can: m_can: don't enable transceiver when probing
  can: mcp251xfd: simplify with spi_get_device_match_data()
  can: mcp251x: simplify with spi_get_device_match_data()
  can: hi311x: simplify with spi_get_device_match_data()
  can: kvaser_pciefd: Add MSI interrupts
  can: kvaser_pciefd: Move reset of DMA RX buffers to the end of the ISR
  can: kvaser_pciefd: Change name of return code variable
  can: kvaser_pciefd: Rename board_irq to pci_irq
  can: kvaser_pciefd: Add unlikely
  can: kvaser_pciefd: Add inline
  can: kvaser_pciefd: Remove unnecessary comment
  can: kvaser_pciefd: Skip redundant NULL pointer check in ISR
  can: kvaser_pciefd: Group #defines together
  can: kvaser_usb: Add support for Kvaser Mini PCIe 1xCAN
  can: kvaser_usb: Add support for Kvaser USBcan Pro 5xCAN
  can: kvaser_usb: Add support for Vining 800
  can: mscan: remove unused struct 'mscan_state'
  Documentation: networking: document ISO 15765-2
  can: xilinx_can: Document driver description to list all supported IPs
  can: isotp: remove ISO 15675-2 specification version where possible
  ...
====================

Link: https://patch.msgid.link/20240621080201.305471-1-mkl@pengutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

In case of reset of VF VSI can be reallocated. To handle this case it
should be properly updated.

Reload representor as vsi->vsi_num can be different than the one stored
when representor was created.

Instead of only changing antispoof do whole VSI configuration for
eswitch.
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

It is needed because subfunction port representor shouldn't configure
the source VSI during representor creation.

Move the code to separate function and call it only in case the VF port
representor is being created.
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

In case of subfunction lock will be taken for whole port creation and
removing. Do the same in VF case.
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

It is used to get representor structure during cleaning.
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

amt.sh is written in bash, not sh.
So, shebang should be bash.
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Acked-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add initial support for Renesas Ethernet-TSN End-station device of R-Car
V4H. The Ethernet End-station can connect to an Ethernet network using a
10 Mbps, 100 Mbps, or 1 Gbps full-duplex link via MII/GMII/RMII/RGMII.
Depending on the connected PHY.

The driver supports Rx checksum and offload and hardware timestamps.

While full power management and suspend/resume is not yet supported the
driver enables runtime PM in order to enable the module clock. While
explicit clock management using clk_enable() would suffice for the
supported SoC, the module could be reused on SoCs where the module is
part of a power domain.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Matthias Schiffer says:

====================
net: dsa: qca8k: cleanup and port isolation

A small cleanup patch, and basically the same changes that were just
accepted for mt7530 to implement port isolation.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Remove a pair of ports from the port matrix when both ports have the
isolated flag set.
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Most of the logic in qca8k_port_bridge_join() and qca8k_port_bridge_leave()
is the same. Refactor to reduce duplication and prepare for reusing the
code for implementing bridge port isolation.

dsa_port_offloads_bridge_dev() is used instead of
dsa_port_offloads_bridge(), passing the bridge in as a struct netdevice *,
as we won't have a struct dsa_bridge in qca8k_port_bridge_flags().

The error handling is changed slightly in the bridge leave case,
returning early and emitting an error message when a regmap access fails.
This shouldn't matter in practice, as there isn't much we can do if
communication with the switch breaks down in the middle of reconfiguration.
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

qca8k_port_bridge_join() set QCA8K_PORT_LOOKUP_CTRL() for i == port twice,
once in the loop handling all other port's masks, and finally at the end
with the accumulated port_mask.

The first time it would incorrectly set the port's own bit in the mask,
only to correct the mistake a moment later. qca8k_port_bridge_leave() had
the same issue, but here the regmap_clear_bits() was a no-op rather than
setting an unintended value.

Remove the duplicate assignment by skipping the whole loop iteration for
i == port. The unintended bit setting doesn't seem to have any negative
effects (even when not reverted right away), so the change is submitted
as a simple cleanup rather than a fix.
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Herve Codina says:

====================
Handle switch reset in mscc-miim

These two patches were previously sent as part of a bigger series:
  https://lore.kernel.org/lkml/20240527161450.326615-1-herve.codina@bootlin.com/

v1 and v2 iterations were handled during the v1 and v2 reviews of this
bigger series. As theses two patches are now ready to be applied, they
were extracted from the bigger series and sent alone in this current
series.

This current v3 series takes into account feedback received during the
bigger series v2 review.

Changes v2 -> v3
  - patch 1
    Drop one useless sentence.
    Add 'Reviewed-by: Andrew Lunn <andrew@lunn.ch>'
    Add 'Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>'

  - patch 2
   Add 'Reviewed-by: Andrew Lunn <andrew@lunn.ch>'

Changes v1 -> v2 (as part of the bigger series iterations)
  - Patch 1
    Improve the reset property description

  - Patch 2
    Fix a wrong reverse x-mass tree declaration
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The mscc-miim device can be impacted by the switch reset, at least when
this device is part of the LAN966x PCI device.

Handle this newly added (optional) resets property.
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add the (optional) resets property.
The mscc-miim device is impacted by the switch reset especially when the
mscc-miim device is used as part of the LAN966x PCI device.
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

James Chapman says:

====================
l2tp: don't use the tunnel socket's sk_user_data in datapath

This series refactors l2tp to not use the tunnel socket's sk_user_data
in the datapath. The main reasons for doing this are

 * to allow for simplifying internal socket cleanup code (to be done
   in a later series)
 * to support multiple L2TPv3 UDP tunnels using the same 5-tuple
   address

When handling received UDP frames, l2tp's current approach is to look
up a session in a per-tunnel list. l2tp uses the tunnel socket's
sk_user_data to derive the tunnel context from the receiving socket.

But this results in the socket and tunnel lifetimes being very tightly
coupled and the tunnel/socket cleanup paths being complicated. The
latter has historically been a source of l2tp bugs and makes the code
more difficult to maintain. Also, if sockets are aliased, we can't
trust that the socket's sk_user_data references the right tunnel
anyway. Hence the desire to not use sk_user_data in the datapath.

The new approach is to lookup sessions in a per-net session list
without first deriving the tunnel:

 * For L2TPv2, the l2tp header has separate tunnel ID and session ID
   fields which can be trivially combined to make a unique 32-bit key
   for per-net session lookup.

 * For L2TPv3, there is no tunnel ID in the packet header, only a
   session ID, which should be unique over all tunnels so can be used
   as a key for per-net session lookup. However, this only works when
   the L2TPv3 session ID really is unique over all tunnels. At least
   one L2TPv3 application is known to use the same session ID in
   different L2TPv3 UDP tunnels, relying on UDP address/ports to
   distinguish them. This worked previously because sessions in UDP
   tunnels were kept in a per-tunnel list. To retain support for this,
   L2TPv3 session ID collisions are managed using a separate per-net
   session hlist, keyed by ID and sk. When looking up a session by ID,
   if there's more than one match, sk is used to find the right one.

L2TPv3 sessions in IP-encap tunnels are already looked up by session
ID in a per-net list. This work has UDP sessions also use the per-net
session list, while allowing for session ID collisions. The existing
per-tunnel hlist becomes a plain list since it is used only in
management and cleanup paths to walk a list of sessions in a given
tunnel.

For better performance, the per-net session lists use IDR. Separate
IDRs are used for L2TPv2 and L2TPv3 sessions to avoid potential key
collisions.

These changes pass l2tp regression tests and improve data forwarding
performance by about 10% in some of my test setups.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The per-tunnel session list is no longer used by the
datapath. However, we still need a list of sessions in the tunnel for
l2tp_session_get_nth, which is used by management code. (An
alternative might be to walk each session IDR list, matching only
sessions of a given tunnel.)

Replace the per-tunnel hlist with a per-tunnel list. In functions
which walk a list of sessions of a tunnel, walk this list instead.
Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

All users of l2tp_tunnel_get_session are now gone so it can be
removed.
Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add generic session getter which uses IDR. Replace all users of
l2tp_tunnel_get_session which uses the per-tunnel session list to use
the generic getter.
Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>