Devlink reload hangs: fix race and lock issue

[William Tu]

Summary:
Machine hangs when doing devlink reload

How to reproduce:
Host:
[root@bu-lab24v ~]# echo '2' > /sys/class/net/ens2f0np0/device/sriov_numvfs

Arm:
root@bu-lab24v-oob:~# uname -r
5.15.0-1027-bluefield
root@bu-lab24v-oob:~# devlink dev eswitch set pci/0000:03:00.0 mode switchdev
root@bu-lab24v-oob:~# devlink dev reload pci/0000:03:00.0
*Hangs*

Arm dmesg:
[ 1089.747409] INFO: task devlink:8753 blocked for more than 120 seconds.
[ 1089.760560] Tainted: G OE 5.15.0-1027-bluefield #29-Ubuntu
[ 1089.775086] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1089.790829] task:devlink state:D stack: 0 pid: 8753 ppid: 5090 flags:0x00000004
[ 1089.790838] Call trace:
[ 1089.790840] __switch_to+0xf8/0x150
[ 1089.790857] __schedule+0x2b8/0x790
[ 1089.790865] schedule+0x64/0x140
[ 1089.790870] schedule_preempt_disabled+0x18/0x24
[ 1089.790874] __mutex_lock.constprop.0+0x1a0/0x680
[ 1089.790878] __mutex_lock_slowpath+0x40/0x90
[ 1089.790883] mutex_lock+0x64/0x70
[ 1089.790887] devl_lock+0x1c/0x30
[ 1089.790893] mlx5_detach_device+0x58/0x190 [mlx5_core]
[ 1089.791055] mlx5_unload_one+0x40/0xe4 [mlx5_core]
[ 1089.791177] mlx5_devlink_reload_down+0x184/0x270 [mlx5_core]
[ 1089.791318] devlink_reload+0x214/0x290

Fixes:
Checking the OFED source code, we found this missing devl trap group
also need to be backported to avoid deadlock.

void mlx5_detach_device(struct mlx5_core_dev *dev, bool suspend)
{
...
#ifdef HAVE_DEVL_PORT_REGISTER
#ifdef HAVE_DEVL_TRAP_GROUPS_REGISTER
        devl_assert_locked(priv_to_devlink(dev));
#else
        devl_lock(devlink);
#endif /* HAVE_DEVL_TRAP_GROUPS_REGISTER */
#endif /* HAVE_DEVL_PORT_REGISTER */
        mutex_lock(&mlx5_intf_mutex);
#ifdef HAVE_DEVL_PORT_REGISTER

Related issue:
#2032378 Devlink backport: fix race and lock issue

So cherry-pick the patch below
commit 852e85a704c2e11c050bdea286bc438aba4f4a22
Author: Jiri Pirko <email address hidden>
Date: Sat Jul 16 13:02:34 2022 +0200

    net: devlink: add unlocked variants of devling_trap*() functions

    Add unlocked variants of devl_trap*() functions to be used in drivers
    called-in with devlink->lock held.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.15.0-1029.31 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-done-jammy-linux-bluefield'. If the problem still exists, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-failed-jammy-linux-bluefield'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!