[PATCH net] net: mana: Cleanup "mana" debugfs dir after cleanup of all children

[Shradha Gupta <shradhagupta@linux.microsoft.com>]

In mana_driver_exit(), mana_debugfs_root gets cleanup before any of it's
children (which happens later in the pci_unregister_driver()).
Due to this, when mana driver is configured as a module and rmmod is
invoked, following stack gets printed along with failure in rmmod command.

[ 2399.317651] BUG: kernel NULL pointer dereference, address: 0000000000000098
[ 2399.318657] #PF: supervisor write access in kernel mode
[ 2399.319057] #PF: error_code(0x0002) - not-present page
[ 2399.319528] PGD 10eb68067 P4D 0
[ 2399.319914] Oops: Oops: 0002 [#1] SMP NOPTI
[ 2399.320308] CPU: 72 UID: 0 PID: 5815 Comm: rmmod Not tainted 6.13.0-rc5+ #89
[ 2399.320986] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 09/28/2024
[ 2399.321892] RIP: 0010:down_write+0x1a/0x50
[ 2399.322303] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 54 49 89 fc e8 9d cd ff ff 31 c0 ba 01 00 00 00 <f0> 49 0f b1 14 24 75 17 65 48 8b 05 f6 84 dd 5f 49 89 44 24 08 4c
[ 2399.323669] RSP: 0018:ff53859d6c663a70 EFLAGS: 00010246
[ 2399.324061] RAX: 0000000000000000 RBX: ff1d4eb505060180 RCX: ffffff8100000000
[ 2399.324620] RDX: 0000000000000001 RSI: 0000000000000064 RDI: 0000000000000098
[ 2399.325167] RBP: ff53859d6c663a78 R08: 00000000000009c4 R09: ff1d4eb4fac90000
[ 2399.325681] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000098
[ 2399.326185] R13: ff1d4e42e1a4a0c8 R14: ff1d4eb538ce0000 R15: 0000000000000098
[ 2399.326755] FS:  00007fe729570000(0000) GS:ff1d4eb2b7200000(0000) knlGS:0000000000000000
[ 2399.327269] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2399.327690] CR2: 0000000000000098 CR3: 00000001c0584005 CR4: 0000000000373ef0
[ 2399.328166] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 2399.328623] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[ 2399.329055] Call Trace:
[ 2399.329243]  <TASK>
[ 2399.329379]  ? show_regs+0x69/0x80
[ 2399.329602]  ? __die+0x25/0x70
[ 2399.329856]  ? page_fault_oops+0x271/0x550
[ 2399.330088]  ? psi_group_change+0x217/0x470
[ 2399.330341]  ? do_user_addr_fault+0x455/0x7b0
[ 2399.330667]  ? finish_task_switch.isra.0+0x91/0x2f0
[ 2399.331004]  ? exc_page_fault+0x73/0x160
[ 2399.331275]  ? asm_exc_page_fault+0x27/0x30
[ 2399.343324]  ? down_write+0x1a/0x50
[ 2399.343631]  simple_recursive_removal+0x4d/0x2c0
[ 2399.343977]  ? __pfx_remove_one+0x10/0x10
[ 2399.344251]  debugfs_remove+0x45/0x70
[ 2399.344511]  mana_destroy_rxq+0x44/0x400 [mana]
[ 2399.344845]  mana_destroy_vport+0x54/0x1c0 [mana]
[ 2399.345229]  mana_detach+0x2f1/0x4e0 [mana]
[ 2399.345466]  ? ida_free+0x150/0x160
[ 2399.345718]  ? __cond_resched+0x1a/0x50
[ 2399.345987]  mana_remove+0xf4/0x1a0 [mana]
[ 2399.346243]  mana_gd_remove+0x25/0x80 [mana]
[ 2399.346605]  pci_device_remove+0x41/0xb0
[ 2399.346878]  device_remove+0x46/0x70
[ 2399.347150]  device_release_driver_internal+0x1e3/0x250
[ 2399.347831]  ? klist_remove+0x81/0xe0
[ 2399.348377]  driver_detach+0x4b/0xa0
[ 2399.348906]  bus_remove_driver+0x83/0x100
[ 2399.349435]  driver_unregister+0x31/0x60
[ 2399.349919]  pci_unregister_driver+0x40/0x90
[ 2399.350492]  mana_driver_exit+0x1c/0xb50 [mana]
[ 2399.351102]  __do_sys_delete_module.constprop.0+0x184/0x320
[ 2399.351664]  ? __fput+0x1a9/0x2d0
[ 2399.352200]  __x64_sys_delete_module+0x12/0x20
[ 2399.352760]  x64_sys_call+0x1e66/0x2140
[ 2399.353316]  do_syscall_64+0x79/0x150
[ 2399.353813]  ? syscall_exit_to_user_mode+0x49/0x230
[ 2399.354346]  ? do_syscall_64+0x85/0x150
[ 2399.354816]  ? irqentry_exit+0x1d/0x30
[ 2399.355287]  ? exc_page_fault+0x7f/0x160
[ 2399.355756]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 2399.356302] RIP: 0033:0x7fe728d26aeb
[ 2399.356776] Code: 73 01 c3 48 8b 0d 45 33 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 15 33 0f 00 f7 d8 64 89 01 48
[ 2399.358372] RSP: 002b:00007ffff954d6f8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
[ 2399.359066] RAX: ffffffffffffffda RBX: 00005609156cc760 RCX: 00007fe728d26aeb
[ 2399.359779] RDX: 000000000000000a RSI: 0000000000000800 RDI: 00005609156cc7c8
[ 2399.360535] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[ 2399.361261] R10: 00007fe728dbeac0 R11: 0000000000000206 R12: 00007ffff954d950
[ 2399.361952] R13: 00005609156cc2a0 R14: 00007ffff954ee5f R15: 00005609156cc760
[ 2399.362688]  </TASK>

Fixes: 6607c17c6c5e ("net: mana: Enable debugfs files for MANA device")
Cc: stable@vger.kernel.org
Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
---
 drivers/net/ethernet/microsoft/mana/gdma_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c
index 2dc0c6ad54be..be95336ce089 100644
--- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
+++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
@@ -1656,9 +1656,9 @@ static int __init mana_driver_init(void)
 
 static void __exit mana_driver_exit(void)
 {
-	debugfs_remove(mana_debugfs_root);
-
 	pci_unregister_driver(&mana_driver);
+
+	debugfs_remove(mana_debugfs_root);
 }
 
 module_init(mana_driver_init);
-- 
2.34.1