I'd like to make netdevsim offload tc-taprio, but currently, this Qdisc
emits a ETHTOOL_GET_TS_INFO call to the driver to make sure that it has
a PTP clock, so that it is reasonably capable of offloading the schedule.

By using the mock PHC driver, that becomes possible.

Hardware timestamping is not necessary, and netdevsim does not support
packet I/O anyway.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20230807193324.4128292-8-vladimir.oltean@nxp.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

When the kernel is compiled with MACsec support, add the
NETIF_F_HW_MACSEC feature to netdevsim devices and implement
macsec_ops.

To allow easy testing of failure from the device, support is limited
to 3 SecY's per netdevsim device, and 1 RXSC per SecY.

v2:
 - nsim_macsec_add_secy, return -ENOSPC if secy_count isn't full but
   we can't find an empty slot (Simon Horman)
 - add sci_to_cpu to make sparse happy (Simon Horman)
 - remove set but not used secy variable (kernel test robot and
   Simon Horman)
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Prepare for devlink reload being called with devlink->lock held and
convert the netdevsim driver to use unlocked devlink API during init and
fini flows. Take devl_lock() in reload_down() and reload_up() ops in the
meantime before reload cmd is converted to take the lock itself.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Similarly to the previous commit, use the devlink instance
lock and let it replace the vfs_lock.

nsim_esw_legacy_enable() was locked by both port lock and
vfs lock so one set of lock/unlocks goes away.

netdevsim's .eswitch_mode_set callback is now ready for
the callback to take the instance lock.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Take advantage of the devlink instance lock for protecting
the port list. This will simplify locking even more once
all devlink callbacks hold the instance lock.

We need to add locking in nsim_dev_port_add_all() which used
to assume higher layer protection when accessing the list.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add support for testing of HW stats support that was added recently, namely
the L3 stats support. L3 stats are provided for devices for which the L3
stats have been turned on, and that were enabled for netdevsim through a
debugfs toggle:

    # echo $ifindex > /sys/kernel/debug/netdevsim/$DEV/hwstats/l3/enable_ifindex

For fully enabled netdevices, netdevsim counts 10pps of ingress traffic and
20pps of egress traffic. Similarly, L3 stats can be disabled for a given
device, and netdevsim ceases pretending there is any HW traffic going on:

    # echo $ifindex > /sys/kernel/debug/netdevsim/$DEV/hwstats/l3/disable_ifindex

Besides this, there is a third toggle to mark a device for future failure:

    # echo $ifindex > /sys/kernel/debug/netdevsim/$DEV/hwstats/l3/fail_next_enable

A future request to enable L3 stats on such netdevice will be bounced by
netdevsim:

    # ip -j l sh dev d | jq '.[].ifindex'
    66
    # echo 66 > /sys/kernel/debug/netdevsim/netdevsim10/hwstats/l3/enable_ifindex
    # echo 66 > /sys/kernel/debug/netdevsim/netdevsim10/hwstats/l3/fail_next_enable
    # ip stats set dev d l3_stats on
    Error: netdevsim: Stats enablement set to fail.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Rename functions serving as driver entry points
from nsim_dev_... to nsim_drv_... this makes the
API boundary between bus and dev clearer.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

max_vfs is a strange little beast because the file
hangs off of nsim's debugfs, but it configures a field
in the bus device. Move it to dev.c, let's look at it
as if the device driver was imposing VF limit based
on FW info (like pci_sriov_set_totalvfs()).

Again, when moving refactor the function not to hold
the vfs lock pointlessly while parsing the input.
Wrap the access from the read side in READ_ONCE()
to appease concurrency checkers. Do not check if
return value from snprintf() is negative...
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since "eswitch" configuration was added bus.c contains
a lot of device details which really belong to dev.c.

Restructure the code while moving it.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

When netdevsim got split into the faux bus vfconfig ended
up in the bus device (think pci_dev) which is strange because
it contains very networky not to say netdevy information.
Move it to nsim_dev, which is the driver "priv" structure
for the device.

To make sure we don't race with probe/remove take
the device lock (much like PCI).

While at it remove the NULL-checking of vfconfigs.
It appears to be pointless.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit d3953819 ("netdevsim: Add max_vfs to bus_dev")
added this file and saved the dentry for no apparent reason.

Link: https://lore.kernel.org/r/20211028211753.22612-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

For testing visibility of mq/mqprio default children.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Don't progress with adding and deleting ports as long as devlink
reload is running.

Fixes: 23809a72 ("netdevsim: Forbid devlink reload when adding or deleting ports")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently netdevsim only supports a single queue per port, which is
insufficient for testing multi-queue TC schedulers e.g. sch_mq.  Extend
the current sysfs interface so that users can create ports with multiple
queues:

$ echo "[ID] [PORT_COUNT] [NUM_QUEUES]" > /sys/bus/netdevsim/new_device

As an example, echoing "2 4 8" creates 4 ports, with 8 queues per port.
Note, this is compatible with the current interface, with default number
of queues set to 1.  For example, echoing "2 4" creates 4 ports with 1
queue per port; echoing "2" simply creates 1 port with 1 queue.
Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

devlink_trap tests for the netdevsim fail due to misspelled
debugfs file name. Change this name, as well as name of callback
function, to match the naming as in the devlink itself - 'trap_drop_counter'.

Test-results:
selftests: drivers/net/netdevsim: devlink_trap.sh
TEST: Initialization                                                [ OK ]
TEST: Trap action                                                   [ OK ]
TEST: Trap metadata                                                 [ OK ]
TEST: Non-existing trap                                             [ OK ]
TEST: Non-existing trap action                                      [ OK ]
TEST: Trap statistics                                               [ OK ]
TEST: Trap group action                                             [ OK ]
TEST: Non-existing trap group                                       [ OK ]
TEST: Trap group statistics                                         [ OK ]
TEST: Trap policer                                                  [ OK ]
TEST: Trap policer binding                                          [ OK ]
TEST: Port delete                                                   [ OK ]
TEST: Device delete                                                 [ OK ]

Fixes: a7b3527a ("drivers: net: netdevsim: add devlink trap_drop_counter_get implementation")
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Whenever query statistics is issued for trap with DROP action,
devlink subsystem would also fill-in statistics 'dropped' field.
In case if device driver did't register callback for hard drop
statistics querying, 'dropped' field will be omitted and not filled.
Add trap_drop_counter_get callback implementation to the netdevsim.
Add new test cases for netdevsim, to test both the callback
functionality, as well as drop statistics alteration check.
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

Implement new devlink ops that allow setting rate node as a parent for
devlink port (leaf) or another devlink node through devlink API.
Expose parent names to netdevsim debugfs in read only mode.
Co-developed-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Implement new devlink ops that allow creation, deletion and setting of
shared/max tx rate of devlink rate nodes through devlink API.
Expose rate node and it's tx rates to netdevsim debugfs.
Co-developed-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Implement callbacks to set/get eswitch mode value. Add helpers to check
current mode.

Instantiate VFs' net devices and devlink ports on switchdev enabling and
remove them on legacy enabling. Changing number of VFs while in
switchdev mode triggers VFs creation/deletion.

Also disable NDO API callback to set VF rate, since it's legacy API.
Switchdev API to set VF rate will be implemented in one of the next
patches.
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Define type of ports, which netdevsim driver currently operates with as
PF. Define new port type - VF, which will be implemented in following
patches. Add helper functions to distinguish them. Add helper function
to get VF index from port index.

Add port indexing logic where PFs' indexes starts from 0, VFs' - from
NSIM_DEV_VF_PORT_INDEX_BASE.
All ports uses same index pool, which means that PF port may be created
with index from VFs' indexes range.
Maximum number of VFs, which the driver can allocate, is limited by
UINT_MAX - BASE.
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Move VFs disabling from device release() to nsim_dev_reload_destroy() to
make VFs disabling and ports removal simultaneous.
This is a requirement for VFs ports implemented in next patches.
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently there is no limit to the number of VFs netdevsim can enable.
In a real systems this value exist and used by the driver.
Fore example, some features might need to consider this value when
allocating memory.

Expose max_vfs variable to debugfs as configurable resource. If are VFs
configured (num_vfs != 0) then changing of max_vfs not allowed.
Co-developed-by: Yuval Avnery <yuvalav@nvidia.com>
Signed-off-by: Yuval Avnery <yuvalav@nvidia.com>
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add support for ethtool FEC and some ethtool error injection.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Allow netdevsim to report "sampled" packets to the psample module by
periodically generating packets from a work queue. The behavior can be
enabled / disabled (default) and the various meta data attributes can be
controlled via debugfs knobs.

This implementation enables both testing of the psample module with all
the optional attributes as well as development of user space
applications on top of psample such as hsflowd and a Wireshark dissector
for psample generic netlink packets.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This adds a new debugfs toggle ('bpf_bind_verifier_accept') that can be
used to make netdevsim reject BPF programs from being accepted by the
verifier. If this toggle (which defaults to true) is set to false,
nsim_bpf_verify_insn() will return EOPNOTSUPP on the last
instruction (after outputting the 'Hello from netdevsim' verifier message).

This makes it possible to check the verification callback in the driver
from test_offload.py in selftests, since the verifier now clears the
verifier log on a successful load, hiding the message from the driver.

Fixes: 6f8a57cc ("bpf: Make verifier log more relevant by default")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/160752225964.110217.12584017165318065332.stgit@toke.dk

Add ethtool ring and coalesce settings support for testing.
Signed-off-by: Antonio Cardace <acardace@redhat.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This will help the refactoring in the next commit
when coalesce and ring settings are added.
Signed-off-by: Antonio Cardace <acardace@redhat.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The Spectrum ASIC has a dedicated table where nexthops (i.e., adjacency
entries) are populated. The size of this table can be controlled via
devlink-resource.

Add such a resource to netdevsim so that its occupancy will reflect the
number of nexthop objects currently programmed to the device.

By limiting the size of the resource, error paths could be exercised and
tested.

Example output:

# devlink resource show netdevsim/netdevsim10
netdevsim/netdevsim10:
  name IPv4 size unlimited unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables none
    resources:
      name fib size unlimited occ 4 unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables none
      name fib-rules size unlimited occ 3 unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables none
  name IPv6 size unlimited unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables none
    resources:
      name fib size unlimited occ 1 unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables none
      name fib-rules size unlimited occ 2 unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables none
  name nexthops size unlimited occ 0 unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables none
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Allow setting UDP_TUNNEL_NIC_INFO_STATIC_IANA_VXLAN.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add the ability to simulate a device with a shared UDP tunnel port
table.

Try to reject the configurations and actions which are not supported
by the core, so we don't get syzcaller etc. warning reports.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

The devlink interface recently gained support for a new "overwrite mask"
parameter that allows specifying how various sub-sections of a flash
component are modified when updating.

Add support for this to netdevsim, to enable easily testing the
interface. Make the allowed overwrite mask values controllable via
a debugfs parameter. This enables testing a flow where the driver
rejects an unsupportable overwrite mask.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add minimal ethtool interface for testing ethtool pause stats.

v2: add missing static on nsim_ethtool_ops
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Now that BPF program/link management is centralized in generic net_device
code, kernel code never queries program id from drivers, so
XDP_QUERY_PROG/XDP_QUERY_PROG_HW commands are unnecessary.

This patch removes all the implementations of those commands in kernel, along
the xdp_attachment_query().

This patch was compile-tested on allyesconfig.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-10-andriin@fb.com

Add UDP tunnel port handlers to our fake driver so we can test
the core infra.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add a dummy callback to set trap group parameters. Return an error when
the 'fail_trap_group_set' debugfs file is set in order to exercise error
paths and verify that error is propagated to user space when should.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Register three dummy packet trap policers with devlink and implement
callbacks to change their parameters and read their counters.

This will be used later on in the series to test the devlink-trap
policer infrastructure.

v2:
* Remove check about burst size being a power of 2 and instead add a
  debugfs knob to fail the operation
* Provide max/min rate/burst size when registering policers and remove
  the validity checks from nsim_dev_devlink_trap_policer_set()
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add new trap ACL which reports flow action cookie in a metadata. Allow
used to setup the cookie using debugfs file.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

nsim_dev_take_snapshot_write() uses nsim_dev and nsim_dev->dummy_region.
So, during this function, these data shouldn't be removed.
But there is no protecting stuff in this function.

There are two similar cases.
1. reload case
reload could be called during nsim_dev_take_snapshot_write().
When reload is being executed, nsim_dev_reload_down() is called and it
calls nsim_dev_reload_destroy(). nsim_dev_reload_destroy() calls
devlink_region_destroy() to destroy nsim_dev->dummy_region.
So, during nsim_dev_take_snapshot_write(), nsim_dev->dummy_region()
would be removed.
At this point, snapshot_write() would access freed pointer.
In order to fix this case, take_snapshot file will be removed before
devlink_region_destroy().
The take_snapshot file will be re-created by ->reload_up().

2. del_device_store case
del_device_store() also could call nsim_dev_reload_destroy()
during nsim_dev_take_snapshot_write(). If so, panic would occur.
This problem is actually the same problem with the first case.
So, this problem will be fixed by the first case's solution.

Test commands:
    modprobe netdevsim
    while :
    do
        echo 1 > /sys/bus/netdevsim/new_device &
        echo 1 > /sys/bus/netdevsim/del_device &
	devlink dev reload netdevsim/netdevsim1 &
	echo 1 > /sys/kernel/debug/netdevsim/netdevsim1/take_snapshot &
    done

Splat looks like:
[   45.564513][  T975] general protection fault, probably for non-canonical address 0xdffffc000000003a: 0000 [#1] SMP DEI
[   45.566131][  T975] KASAN: null-ptr-deref in range [0x00000000000001d0-0x00000000000001d7]
[   45.566135][  T975] CPU: 1 PID: 975 Comm: bash Not tainted 5.5.0+ #322
[   45.569020][  T975] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[   45.569026][  T975] RIP: 0010:__mutex_lock+0x10a/0x14b0
[   45.570518][  T975] Code: 08 84 d2 0f 85 7f 12 00 00 44 8b 0d 10 23 65 02 45 85 c9 75 29 49 8d 7f 68 48 b8 00 00 00 0f
[   45.570522][  T975] RSP: 0018:ffff888046ccfbf0 EFLAGS: 00010206
[   45.572305][  T975] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   45.572308][  T975] RDX: 000000000000003a RSI: ffffffffac926440 RDI: 00000000000001d0
[   45.576843][  T975] RBP: ffff888046ccfd70 R08: ffffffffab610645 R09: 0000000000000000
[   45.576847][  T975] R10: ffff888046ccfd90 R11: ffffed100d6360ad R12: 0000000000000000
[   45.578471][  T975] R13: dffffc0000000000 R14: ffffffffae1976c0 R15: 0000000000000168
[   45.578475][  T975] FS:  00007f614d6e7740(0000) GS:ffff88806c400000(0000) knlGS:0000000000000000
[   45.581492][  T975] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   45.582942][  T975] CR2: 00005618677d1cf0 CR3: 000000005fb9c002 CR4: 00000000000606e0
[   45.584543][  T975] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   45.586633][  T975] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   45.589889][  T975] Call Trace:
[   45.591445][  T975]  ? devlink_region_snapshot_create+0x55/0x4a0
[   45.601250][  T975]  ? mutex_lock_io_nested+0x1380/0x1380
[   45.602817][  T975]  ? mutex_lock_io_nested+0x1380/0x1380
[   45.603875][  T975]  ? mark_held_locks+0xa5/0xe0
[   45.604769][  T975]  ? _raw_spin_unlock_irqrestore+0x2d/0x50
[   45.606147][  T975]  ? __mutex_unlock_slowpath+0xd0/0x670
[   45.607723][  T975]  ? crng_backtrack_protect+0x80/0x80
[   45.613530][  T975]  ? wait_for_completion+0x390/0x390
[   45.615152][  T975]  ? devlink_region_snapshot_create+0x55/0x4a0
[   45.616834][  T975]  devlink_region_snapshot_create+0x55/0x4a0
[ ... ]

Fixes: 4418f862 ("netdevsim: implement support for devlink region and snapshots")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

devlink reload destroys resources and allocates resources again.
So, when devices and ports resources are being used, devlink reload
function should not be executed. In order to avoid this race, a new
lock is added and new_port() and del_port() call devlink_reload_disable()
and devlink_reload_enable().

Thread0                      Thread1
{new/del}_port()             {new/del}_port()
devlink_reload_disable()
                             devlink_reload_disable()
devlink_reload_enable()
                             //here
                             devlink_reload_enable()

Before Thread1's devlink_reload_enable(), the devlink is already allowed
to execute reload because Thread0 allows it. devlink reload disable/enable
variable type is bool. So the above case would exist.
So, disable/enable should be executed atomically.
In order to do that, a new lock is used.

Test commands:
    modprobe netdevsim
    echo 1 > /sys/bus/netdevsim/new_device
    while :
    do
        echo 1 > /sys/devices/netdevsim1/new_port &
        echo 1 > /sys/devices/netdevsim1/del_port &
        devlink dev reload netdevsim/netdevsim1 &
    done

Splat looks like:
[   23.342145][  T932] DEBUG_LOCKS_WARN_ON(mutex_is_locked(lock))
[   23.342159][  T932] WARNING: CPU: 0 PID: 932 at kernel/locking/mutex-debug.c:103 mutex_destroy+0xc7/0xf0
[   23.344182][  T932] Modules linked in: netdevsim openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_dx
[   23.346485][  T932] CPU: 0 PID: 932 Comm: devlink Not tainted 5.5.0+ #322
[   23.347696][  T932] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[   23.348893][  T932] RIP: 0010:mutex_destroy+0xc7/0xf0
[   23.349505][  T932] Code: e0 07 83 c0 03 38 d0 7c 04 84 d2 75 2e 8b 05 00 ac b0 02 85 c0 75 8b 48 c7 c6 00 5e 07 96 40
[   23.351887][  T932] RSP: 0018:ffff88806208f810 EFLAGS: 00010286
[   23.353963][  T932] RAX: dffffc0000000008 RBX: ffff888067f6f2c0 RCX: ffffffff942c4bd4
[   23.355222][  T932] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff96dac5b4
[   23.356169][  T932] RBP: ffff888067f6f000 R08: fffffbfff2d235a5 R09: fffffbfff2d235a5
[   23.357160][  T932] R10: 0000000000000001 R11: fffffbfff2d235a4 R12: ffff888067f6f208
[   23.358288][  T932] R13: ffff88806208fa70 R14: ffff888067f6f000 R15: ffff888069ce3800
[   23.359307][  T932] FS:  00007fe2a3876740(0000) GS:ffff88806c000000(0000) knlGS:0000000000000000
[   23.360473][  T932] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   23.361319][  T932] CR2: 00005561357aa000 CR3: 000000005227a006 CR4: 00000000000606f0
[   23.362323][  T932] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   23.363417][  T932] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   23.364414][  T932] Call Trace:
[   23.364828][  T932]  nsim_dev_reload_destroy+0x77/0xb0 [netdevsim]
[   23.365655][  T932]  nsim_dev_reload_down+0x84/0xb0 [netdevsim]
[   23.366433][  T932]  devlink_reload+0xb1/0x350
[   23.367010][  T932]  genl_rcv_msg+0x580/0xe90

[ ...]

[   23.531729][ T1305] kernel BUG at lib/list_debug.c:53!
[   23.532523][ T1305] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[   23.533467][ T1305] CPU: 2 PID: 1305 Comm: bash Tainted: G        W         5.5.0+ #322
[   23.534962][ T1305] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[   23.536503][ T1305] RIP: 0010:__list_del_entry_valid+0xe6/0x150
[   23.538346][ T1305] Code: 89 ea 48 c7 c7 00 73 1e 96 e8 df f7 4c ff 0f 0b 48 c7 c7 60 73 1e 96 e8 d1 f7 4c ff 0f 0b 44
[   23.541068][ T1305] RSP: 0018:ffff888047c27b58 EFLAGS: 00010282
[   23.542001][ T1305] RAX: 0000000000000054 RBX: ffff888067f6f318 RCX: 0000000000000000
[   23.543051][ T1305] RDX: 0000000000000054 RSI: 0000000000000008 RDI: ffffed1008f84f61
[   23.544072][ T1305] RBP: ffff88804aa0fca0 R08: ffffed100d940539 R09: ffffed100d940539
[   23.545085][ T1305] R10: 0000000000000001 R11: ffffed100d940538 R12: ffff888047c27cb0
[   23.546422][ T1305] R13: ffff88806208b840 R14: ffffffff981976c0 R15: ffff888067f6f2c0
[   23.547406][ T1305] FS:  00007f76c0431740(0000) GS:ffff88806c800000(0000) knlGS:0000000000000000
[   23.548527][ T1305] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   23.549389][ T1305] CR2: 00007f5048f1a2f8 CR3: 000000004b310006 CR4: 00000000000606e0
[   23.550636][ T1305] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   23.551578][ T1305] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   23.552597][ T1305] Call Trace:
[   23.553004][ T1305]  mutex_remove_waiter+0x101/0x520
[   23.553646][ T1305]  __mutex_lock+0xac7/0x14b0
[   23.554218][ T1305]  ? nsim_dev_port_del+0x4e/0x140 [netdevsim]
[   23.554908][ T1305]  ? mutex_lock_io_nested+0x1380/0x1380
[   23.555570][ T1305]  ? _parse_integer+0xf0/0xf0
[   23.556043][ T1305]  ? kstrtouint+0x86/0x110
[   23.556504][ T1305]  ? nsim_dev_port_del+0x4e/0x140 [netdevsim]
[   23.557133][ T1305]  nsim_dev_port_del+0x4e/0x140 [netdevsim]
[   23.558024][ T1305]  del_port_store+0xcc/0xf0 [netdevsim]
[ ... ]

Fixes: 75ba029f ("netdevsim: implement proper devlink reload")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When module is being initialized, __init() calls bus_register() and
driver_register().
These functions internally create various resources and sysfs files.
The sysfs files are used for basic operations(add/del device).
/sys/bus/netdevsim/new_device
/sys/bus/netdevsim/del_device

These sysfs files use netdevsim resources, they are mostly allocated
and initialized in ->probe() function, which is nsim_dev_probe().
But, sysfs files could be executed before ->probe() is finished.
So, accessing uninitialized data would occur.

Another problem is very similar.
/sys/bus/netdevsim/new_device internally creates sysfs files.
/sys/devices/netdevsim<id>/new_port
/sys/devices/netdevsim<id>/del_port

These sysfs files also use netdevsim resources, they are mostly allocated
and initialized in creating device routine, which is nsim_bus_dev_new().
But they also could be executed before nsim_bus_dev_new() is finished.
So, accessing uninitialized data would occur.

To fix these problems, this patch adds flags, which means whether the
operation is finished or not.
The flag variable 'nsim_bus_enable' means whether netdevsim bus was
initialized or not.
This is protected by nsim_bus_dev_list_lock.
The flag variable 'nsim_bus_dev->init' means whether nsim_bus_dev was
initialized or not.
This could be used in {new/del}_port_store() with no lock.

Test commands:
    #SHELL1
    modprobe netdevsim
    while :
    do
        echo "1 1" > /sys/bus/netdevsim/new_device
        echo "1 1" > /sys/bus/netdevsim/del_device
    done

    #SHELL2
    while :
    do
        echo 1 > /sys/devices/netdevsim1/new_port
        echo 1 > /sys/devices/netdevsim1/del_port
    done

Splat looks like:
[   47.508954][ T1008] general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 I
[   47.510793][ T1008] KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
[   47.511963][ T1008] CPU: 2 PID: 1008 Comm: bash Not tainted 5.5.0+ #322
[   47.512823][ T1008] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[   47.514041][ T1008] RIP: 0010:__mutex_lock+0x10a/0x14b0
[   47.514699][ T1008] Code: 08 84 d2 0f 85 7f 12 00 00 44 8b 0d 10 23 65 02 45 85 c9 75 29 49 8d 7f 68 48 b8 00 00 00 0f
[   47.517163][ T1008] RSP: 0018:ffff888059b4fbb0 EFLAGS: 00010206
[   47.517802][ T1008] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
[   47.518941][ T1008] RDX: 0000000000000021 RSI: ffffffff85926440 RDI: 0000000000000108
[   47.519732][ T1008] RBP: ffff888059b4fd30 R08: ffffffffc073fad0 R09: 0000000000000000
[   47.520729][ T1008] R10: ffff888059b4fd50 R11: ffff88804bb38040 R12: 0000000000000000
[   47.521702][ T1008] R13: dffffc0000000000 R14: ffffffff871976c0 R15: 00000000000000a0
[   47.522760][ T1008] FS:  00007fd4be05a740(0000) GS:ffff88806c800000(0000) knlGS:0000000000000000
[   47.523877][ T1008] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   47.524627][ T1008] CR2: 0000561c82b69cf0 CR3: 0000000065dd6004 CR4: 00000000000606e0
[   47.527662][ T1008] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   47.528604][ T1008] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   47.529531][ T1008] Call Trace:
[   47.529874][ T1008]  ? nsim_dev_port_add+0x50/0x150 [netdevsim]
[   47.530470][ T1008]  ? mutex_lock_io_nested+0x1380/0x1380
[   47.531018][ T1008]  ? _kstrtoull+0x76/0x160
[   47.531449][ T1008]  ? _parse_integer+0xf0/0xf0
[   47.531874][ T1008]  ? kernfs_fop_write+0x1cf/0x410
[   47.532330][ T1008]  ? sysfs_file_ops+0x160/0x160
[   47.532773][ T1008]  ? kstrtouint+0x86/0x110
[   47.533168][ T1008]  ? nsim_dev_port_add+0x50/0x150 [netdevsim]
[   47.533721][ T1008]  nsim_dev_port_add+0x50/0x150 [netdevsim]
[   47.534336][ T1008]  ? sysfs_file_ops+0x160/0x160
[   47.534858][ T1008]  new_port_store+0x99/0xb0 [netdevsim]
[   47.535439][ T1008]  ? del_port_store+0xb0/0xb0 [netdevsim]
[   47.536035][ T1008]  ? sysfs_file_ops+0x112/0x160
[   47.536544][ T1008]  ? sysfs_kf_write+0x3b/0x180
[   47.537029][ T1008]  kernfs_fop_write+0x276/0x410
[   47.537548][ T1008]  ? __sb_start_write+0x215/0x2e0
[   47.538110][ T1008]  vfs_write+0x197/0x4a0
[ ... ]

Fixes: f9d9db47 ("netdevsim: add bus attributes to add new and delete devices")
Fixes: 794b2c05 ("netdevsim: extend device attrs to support port addition and deletion")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>