The same ATU function are used by drivers based on qca8k family switch.
Move the bulk read/write helper to common code to declare these shared
ATU functions in common code.
These helper will be dropped when regmap correctly support bulk
read/write.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The same reg table and read/write/rmw function are used by drivers
based on qca8k family switch.
Move them to common code to make it accessible also by other drivers.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The same MIB struct is used by drivers based on qca8k family switch. Move
it to common code to make it accessible also by other drivers.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Some switch may not support mib autocast feature and require the legacy
way of reading the regs directly.
Make the mib autocast feature optional and permit to declare support for
it using match_data struct in a dedicated qca8k_info_ops struct.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Using of_device_get_match_data is expensive. Cache match data to speed
up access and rework user of match data to use the new cached value.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Since we have a proper endianness converters for BE 48-bit data use
them.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220726144906.5217-1-andriy.shevchenko@linux.intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Correct spelling on 'non-existent' in comment
Signed-off-by: Ruffalo Lavoisier <RuffaloLavoisier@gmail.com>
Link: https://lore.kernel.org/r/20220728032854.151180-1-RuffaloLavoisier@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Fix following includecheck warning:
./drivers/net/ethernet/mellanox/mlxsw/core_linecard_dev.c: linux/err.h is included more than once.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20220727233801.23781-1-yang.lee@linux.alibaba.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Add a Makefile which takes care of installing the selftests in
tools/testing/selftests/drivers/net/dsa. This can be used to install all
DSA specific selftests and forwarding.config using the same approach as
for the selftests in tools/testing/selftests/net/forwarding.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220727191642.480279-1-martin.blumenstingl@googlemail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Moshe Shemesh says:

====================
Take devlink lock on mlx4 and mlx5 callbacks

Prepare mlx4 and mlx5 drivers to have all devlink callbacks called with
devlink instance locked. Change mlx4 driver to use devl_ API where
needed to have devlink reload callbacks locked. Change mlx5 driver to
use devl_ API where needed to have devlink reload and devlink health
callbacks locked.

As mlx5 is the only driver which needed changes to enable calling health
callbacks with devlink instance locked, this patchset also removes
DEVLINK_NL_FLAG_NO_LOCK flag from devlink health callbacks.

This patchset will be followed by a patchset that will remove
DEVLINK_NL_FLAG_NO_LOCK flag from devlink and will remove devlink_mutex.
====================

Link: https://lore.kernel.org/r/1659023630-32006-1-git-send-email-moshe@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Let the core take the devlink instance lock around health callbacks and
remove the now redundant locking in the drivers.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Change devlink instance locks in mlx5 driver to have devlink health
recovery callback locked, while keeping all driver paths which lead to
devl_ API functions called by the driver locked.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Change devlink instance locks in mlx4 driver to have devlink reload
callback locked, while keeping all driver paths which leads to devl_ API
functions called by the mlx4 driver locked.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Use devl_ API to call devl_port_register() and devl_port_unregister()
instead of devlink_port_register() and devlink_port_unregister(). Add
devlink instance lock in mlx4 driver paths to these functions.

This will be used by the downstream patch to invoke mlx4 devlink reload
callbacks with devlink lock held.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Use devl_ API to call devl_region_create() and devl_region_destroy()
instead of devlink_region_create() and devlink_region_destroy().
Add devlink instance lock in mlx4 driver paths to these functions.

This will be used by the downstream patch to invoke mlx4 devlink reload
callbacks with devlink lock held.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Change devlink instance locks in mlx5 driver to have devlink reload
callbacks locked, while keeping all driver paths which lead to devl_ API
functions called by the driver locked.

Add mlx5_load_one_devl_locked() and mlx5_unload_one_devl_locked() which
are used by the paths which are already locked such as devlink reload
callbacks.

This patch makes the driver use devl_ API also for traps register as
these functions are called from the driver paths parallel to reload that
requires locking now.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Refactor fw reset code to have the unload driver part done on
mlx5_fw_reset_complete_reload(), so if it was called by the PF which
initiated the reload fw activate flow, the unload part will be handled
by the mlx5_devlink_reload_fw_activate() callback itself and not by the
reset event work.

This will be used by the downstream patch to invoke devlink reload
callbacks with devlink lock held.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

After mlx4 driver is converted to do locked reload,
devlink_region_snapshot_create() may be called from both locked and
unlocked context.

Note that in mlx4 region snapshots could be created on any command
failure. That can happen in any flow that involves commands to FW,
which means most of the driver flows.

So resolve this by removing dependency on devlink->lock for region
snapshots list consistency and introduce new mutex to ensure it.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

After mlx4 driver is converted to do locked reload, functions to get/put
regions snapshot ID may be called from both locked and unlocked context.

So resolve this by removing dependency on devlink->lock for region
snapshot ID tracking by using internal xa_lock() to maintain
shapshot_ids xa_array consistency.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Vikas Gupta says:

====================
add framework for selftests in devlink

Add support for selftests in the devlink framework.
Adds a callback .selftests_check and .selftests_run in devlink_ops.
User can add test(s) suite which is subsequently passed to the driver
and driver can opt for running particular tests based on its capabilities.

Patchset adds a flash based test for the bnxt_en driver.
====================

Link: https://lore.kernel.org/r/20220727165721.37959-1-vikas.gupta@broadcom.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Add callbacks
=============
.selftest_check: returns true for flash selftest.
.selftest_run: runs a flash selftest.

Also, refactor NVM APIs so that they can be
used with devlink and ethtool both.
Signed-off-by: Vikas Gupta <vikas.gupta@broadcom.com>
Reviewed-by: Andy Gospodarek <gospo@broadcom.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add a framework for running selftests.
Framework exposes devlink commands and test suite(s) to the user
to execute and query the supported tests by the driver.

Below are new entries in devlink_nl_ops
devlink_nl_cmd_selftests_show_doit/dumpit: To query the supported
selftests by the drivers.
devlink_nl_cmd_selftests_run: To execute selftests. Users can
provide a test mask for executing group tests or standalone tests.

Documentation/networking/devlink/ path is already part of MAINTAINERS &
the new files come under this path. Hence no update needed to the
MAINTAINERS
Signed-off-by: Vikas Gupta <vikas.gupta@broadcom.com>
Reviewed-by: Andy Gospodarek <gospo@broadcom.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Tariq Toukan says:

====================
mlx5e use TLS TX pool to improve connection rate

To offload encryption operations, the mlx5 device maintains state and
keeps track of every kTLS device-offloaded connection.  Two HW objects
are used per TX context of a kTLS offloaded connection: a. Transport
interface send (TIS) object, to reach the HW context.  b. Data Encryption
Key (DEK) to perform the crypto operations.

These two objects are created and destroyed per TLS TX context, via FW
commands.  In total, 4 FW commands are issued per TLS TX context, which
seriously limits the connection rate.

In this series, we aim to save creation and destroy of TIS objects by
recycling them.  Upon recycling of a TIS, the HW still needs to be
notified for the re-mapping between a TIS and a context. This is done by
posting WQEs via an SQ, significantly faster API than the FW command
interface.

A pool is used for recycling. The pool dynamically interacts to the load
and connection rate, growing and shrinking accordingly.

Saving the TIS FW commands per context increases connection rate by ~42%,
from 11.6K to 16.5K connections per sec.

Connection rate is still limited by FW bottleneck due to the remaining
per context FW commands (DEK create/destroy). This will soon be addressed
in a followup series.  By combining the two series, the FW bottleneck
will be released, and a significantly higher (about 100K connections per
sec) kTLS TX device-offloaded connection rate is reached.
====================

Link: https://lore.kernel.org/r/20220727094346.10540-1-tariqt@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Let the TLS TX recycle pool be more flexible in size, by continuously
and dynamically allocating and releasing HW resources in response to
changes in the connections rate and load.

Allocate and release pool entries in bulks (16). Use a workqueue to
release/allocate in the background. Allocate a new bulk when the pool
size goes lower than the low threshold (1K). Symmetric operation is done
when the pool size gets greater than the upper threshold (4K).

Every idle pool entry holds: 1 TIS, 1 DEK (HW resources), in addition to
~100 bytes in host memory.

Start with an empty pool to minimize memory and HW resources waste for
non-TLS users that have the device-offload TLS enabled.

Upon a new request, in case the pool is empty, do not wait for a whole bulk
allocation to complete.  Instead, trigger an instant allocation of a single
resource to reduce latency.

Performance tests:
Before: 11,684 CPS
After:  16,556 CPS
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The transport interface send (TIS) object is responsible for performing
all transport related operations of the transmit side.  The ConnectX HW
uses a TIS object to save and access the TLS crypto information and state
of an offloaded TX kTLS connection.

Before this patch, we used to create a new TIS per connection and destroy
it once it’s closed. Every create and destroy of a TIS is a FW command.

Same applies for the private TLS context, where we used to dynamically
allocate and free it per connection.

Resources recycling reduce the impact of the allocation/free operations
and helps speeding up the connection rate.

In this feature we maintain a pool of TX objects and use it to recycle
the resources instead of re-creating them per connection.

A cached TIS popped from the pool is updated to serve the new connection
via the fast-path HW interface, updating the tls static and progress
params. This is a very fast operation, significantly faster than FW
commands.

On recycling, a WQE fence is required after the context params change.
This guarantees that the data is sent after the context has been
successfully updated in hardware, and that the context modification
doesn't interfere with existing traffic.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Let the caller of mlx5e_ktls_tx_handle_ooo() take care of updating the
stats, according to the returned value.  As the switch/case blocks are
already there, this change saves unnecessary branches in the handler.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

TLS TIS objects have a defined role in mapping and reaching the HW TLS
contexts.  Some standard TIS attributes (like LAG port affinity) are
not relevant for them.

Use a dedicated TLS TIS create function instead of the generic
mlx5e_create_tis.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Multiple TLS device-offloaded contexts can be added in parallel via
concurrent calls to .tls_dev_add, while calls to .tls_dev_del are
sequential in tls_device_gc_task.

This is not a sustainable behavior. This creates a rate gap between add
and del operations (addition rate outperforms the deletion rate).  When
running for enough time, the TLS device resources could get exhausted,
failing to offload new connections.

Replace the single-threaded garbage collector work with a per-context
alternative, so they can be handled on several cores in parallel. Use
a new dedicated destruct workqueue for this.

Tested with mlx5 device:
Before: 22141 add/sec,   103 del/sec
After:  11684 add/sec, 11684 del/sec
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

TLS context destructor can be run in atomic context. Cleanup operations
for device-offloaded contexts could require access and interaction with
the device callbacks, which might sleep. Hence, the cleanup of such
contexts must be deferred and completed inside an async work.

For all others, this is not necessary, as cleanup is atomic. Invoke
cleanup immediately for them, avoiding queueing redundant gc work.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The return from the call to tls_rx_msg_size() is int, it can be
a negative error code, however this is being assigned to an
unsigned long variable 'sz', so making 'sz' an int.

Eliminate the following coccicheck warning:
./net/tls/tls_strp.c:211:6-8: WARNING: Unsigned expression compared with zero: sz < 0
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220728031019.32838-1-yang.lee@linux.alibaba.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Jakub Kicinski says:

====================
tls: rx: follow ups to rx work

A selection of unrelated changes. First some selftest polishing.
Next a change to rcvtimeo handling for locking based on an exchange
with Eric. Follow up to Paolo's comments from yesterday. Last but
not least a fix to a false positive warning, turns out I've been
testing with DEBUG_NET=n this whole time.
====================

Link: https://lore.kernel.org/r/20220727031524.358216-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

I went too far in the accessor conversion, we can't use tls_strp_msg()
after decryption because the message may not be ready. What we care
about on this path is that the output skb is detached, i.e. we didn't
somehow just turn around and used the input skb with its TCP data
still attached. So look at the anchor directly.

Fixes: 84c61fe1 ("tls: rx: do not use the standard strparser")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Paolo points out that there seems to be no strong reason strparser
users a single threaded workqueue. Perhaps there were some performance
or pinning considerations? Since we don't know (and it's the slow path)
let's default to the most natural, multi-threaded choice.

Also rename the workqueue to "tls-".
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Eric indicates that restarting rcvtimeo on every wait may be fine.
I thought that we should consider it cumulative, and made
tls_rx_reader_lock() return the remaining timeo after acquiring
the reader lock.

tls_rx_rec_wait() gets its timeout passed in by value so it
does not keep track of time previously spent.

Make the lock waiting consistent with tls_rx_rec_wait() - don't
keep track of time spent.

Read the timeo fresh in tls_rx_rec_wait().
It's unclear to me why callers are supposed to cache the value.

Link: https://lore.kernel.org/all/CANn89iKcmSfWgvZjzNGbsrndmCch2HC_EPZ7qmGboDNaWoviNQ@mail.gmail.com/Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add a handful of memory randomizations and precise length checks.
Nothing is really broken here, I did this to increase confidence
when debugging. It does fix a GCC warning, tho. Apparently GCC
recognizes that memory needs to be initialized for send() but
does not recognize that for write().
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

delete extra space and tab in blank line, there is no functional change.
Signed-off-by: Xie Shaowen <studentxswpy@163.com>
Link: https://lore.kernel.org/r/20220727081253.3043941-1-studentxswpy@163.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

No conflicts.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull networking fixes from Jakub Kicinski:
 "Including fixes from bluetooth and netfilter, no known blockers for
  the release.

  Current release - regressions:

   - wifi: mac80211: do not abuse fq.lock in ieee80211_do_stop(), fix
     taking the lock before its initialized

   - Bluetooth: mgmt: fix double free on error path

  Current release - new code bugs:

   - eth: ice: fix tunnel checksum offload with fragmented traffic

  Previous releases - regressions:

   - tcp: md5: fix IPv4-mapped support after refactoring, don't take the
     pure v6 path

   - Revert "tcp: change pingpong threshold to 3", improving detection
     of interactive sessions

   - mld: fix netdev refcount leak in mld_{query | report}_work() due to
     a race

   - Bluetooth:
      - always set event mask on suspend, avoid early wake ups
      - L2CAP: fix use-after-free caused by l2cap_chan_put

   - bridge: do not send empty IFLA_AF_SPEC attribute

  Previous releases - always broken:

   - ping6: fix memleak in ipv6_renew_options()

   - sctp: prevent null-deref caused by over-eager error paths

   - virtio-net: fix the race between refill work and close, resulting
     in NAPI scheduled after close and a BUG()

   - macsec:
      - fix three netlink parsing bugs
      - avoid breaking the device state on invalid change requests
      - fix a memleak in another error path

  Misc:

   - dt-bindings: net: ethernet-controller: rework 'fixed-link' schema

   - two more batches of sysctl data race adornment"

* tag 'net-5.19-final' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (67 commits)
  stmmac: dwmac-mediatek: fix resource leak in probe
  ipv6/addrconf: fix a null-ptr-deref bug for ip6_ptr
  net: ping6: Fix memleak in ipv6_renew_options().
  net/funeth: Fix fun_xdp_tx() and XDP packet reclaim
  sctp: leave the err path free in sctp_stream_init to sctp_stream_free
  sfc: disable softirqs for ptp TX
  ptp: ocp: Select CRC16 in the Kconfig.
  tcp: md5: fix IPv4-mapped support
  virtio-net: fix the race between refill work and close
  mptcp: Do not return EINPROGRESS when subflow creation succeeds
  Bluetooth: L2CAP: Fix use-after-free caused by l2cap_chan_put
  Bluetooth: Always set event mask on suspend
  Bluetooth: mgmt: Fix double free on error path
  wifi: mac80211: do not abuse fq.lock in ieee80211_do_stop()
  ice: do not setup vlan for loopback VSI
  ice: check (DD | EOF) bits on Rx descriptor rather than (EOP | RS)
  ice: Fix VSIs unable to share unicast MAC
  ice: Fix tunnel checksum offload with fragmented traffic
  ice: Fix max VLANs available for VF
  netfilter: nft_queue: only allow supported familes and hooks
  ...

If mediatek_dwmac_clks_config() fails, then call stmmac_remove_config_dt()
before returning.  Otherwise it is a resource leak.

Fixes: fa4b3ca6 ("stmmac: dwmac-mediatek: fix clock issue")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YuJ4aZyMUlG6yGGa@kiliSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Change net device's MTU to smaller than IPV6_MIN_MTU or unregister
device while matching route. That may trigger null-ptr-deref bug
for ip6_ptr probability as following.

=========================================================
BUG: KASAN: null-ptr-deref in find_match.part.0+0x70/0x134
Read of size 4 at addr 0000000000000308 by task ping6/263

CPU: 2 PID: 263 Comm: ping6 Not tainted 5.19.0-rc7+ #14
Call trace:
 dump_backtrace+0x1a8/0x230
 show_stack+0x20/0x70
 dump_stack_lvl+0x68/0x84
 print_report+0xc4/0x120
 kasan_report+0x84/0x120
 __asan_load4+0x94/0xd0
 find_match.part.0+0x70/0x134
 __find_rr_leaf+0x408/0x470
 fib6_table_lookup+0x264/0x540
 ip6_pol_route+0xf4/0x260
 ip6_pol_route_output+0x58/0x70
 fib6_rule_lookup+0x1a8/0x330
 ip6_route_output_flags_noref+0xd8/0x1a0
 ip6_route_output_flags+0x58/0x160
 ip6_dst_lookup_tail+0x5b4/0x85c
 ip6_dst_lookup_flow+0x98/0x120
 rawv6_sendmsg+0x49c/0xc70
 inet_sendmsg+0x68/0x94

Reproducer as following:
Firstly, prepare conditions:
$ip netns add ns1
$ip netns add ns2
$ip link add veth1 type veth peer name veth2
$ip link set veth1 netns ns1
$ip link set veth2 netns ns2
$ip netns exec ns1 ip -6 addr add 2001:0db8:0:f101::1/64 dev veth1
$ip netns exec ns2 ip -6 addr add 2001:0db8:0:f101::2/64 dev veth2
$ip netns exec ns1 ifconfig veth1 up
$ip netns exec ns2 ifconfig veth2 up
$ip netns exec ns1 ip -6 route add 2000::/64 dev veth1 metric 1
$ip netns exec ns2 ip -6 route add 2001::/64 dev veth2 metric 1

Secondly, execute the following two commands in two ssh windows
respectively:
$ip netns exec ns1 sh
$while true; do ip -6 addr add 2001:0db8:0:f101::1/64 dev veth1; ip -6 route add 2000::/64 dev veth1 metric 1; ping6 2000::2; done

$ip netns exec ns1 sh
$while true; do ip link set veth1 mtu 1000; ip link set veth1 mtu 1500; sleep 5; done

It is because ip6_ptr has been assigned to NULL in addrconf_ifdown() firstly,
then ip6_ignore_linkdown() accesses ip6_ptr directly without NULL check.

	cpu0			cpu1
fib6_table_lookup
__find_rr_leaf
			addrconf_notify [ NETDEV_CHANGEMTU ]
			addrconf_ifdown
			RCU_INIT_POINTER(dev->ip6_ptr, NULL)
find_match
ip6_ignore_linkdown

So we can add NULL check for ip6_ptr before using in ip6_ignore_linkdown() to
fix the null-ptr-deref bug.

Fixes: dcd1f572 ("net/ipv6: Remove fib6_idev")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220728013307.656257-1-william.xuanziyang@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>