scsi: hisi_sas: Fix Null point exception after call debugfs_remove_recursive()

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7GRU1
CVE: NA

---------------------------------------------------------------------

If init debugfs failed and call debugfs_remove_recursive() when device
register. We found it will trigger NULL point exception after calling
debugfs_remove_recursive() again when device remove.

[ 1665.467244] hisi_sas_v3_hw 0000:b4:02.0: failed to init debugfs!

[ 1669.836708] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a0
[ 1669.872669] pc : down_write+0x24/0x70
[ 1669.876315] lr : down_write+0x1c/0x70
[ 1669.879961] sp : ffff000036f53a30
[ 1669.883260] x29: ffff000036f53a30 x28: ffffa027c31549f8
[ 1669.888547] x27: ffffa027c3140000 x26: 0000000000000000
[ 1669.893834] x25: ffffa027bf37c270 x24: ffffa027bf37c270
[ 1669.899122] x23: ffff0000095406b8 x22: ffff0000095406a8
[ 1669.904408] x21: 0000000000000000 x20: ffffa027bf37c310
[ 1669.909695] x19: 00000000000000a0 x18: ffff8027dcd86f10
[ 1669.914982] x17: 0000000000000000 x16: 0000000000000000
[ 1669.920268] x15: 0000000000000000 x14: ffffa0274014f870
[ 1669.925555] x13: 0000000000000040 x12: 0000000000000228
[ 1669.930842] x11: 0000000000000020 x10: 0000000000000bb0
[ 1669.936129] x9 : ffff000036f537f0 x8 : ffff80273088ca10
[ 1669.941416] x7 : 000000000000001d x6 : 00000000ffffffff
[ 1669.946702] x5 : ffff000008a36310 x4 : ffff80273088be00
[ 1669.951989] x3 : ffff000009513e90 x2 : 0000000000000000
[ 1669.957276] x1 : 00000000000000a0 x0 : ffffffff00000001
[ 1669.962563] Call trace:
[ 1669.965000]  down_write+0x24/0x70
[ 1669.968301]  debugfs_remove_recursive+0x5c/0x1b0
[ 1669.972905]  hisi_sas_debugfs_exit+0x24/0x30 [hisi_sas_main]
[ 1669.978541]  hisi_sas_v3_remove+0x130/0x150 [hisi_sas_v3_hw]
[ 1669.984175]  pci_device_remove+0x48/0xd8
[ 1669.988082]  device_release_driver_internal+0x1b4/0x250
[ 1669.993282]  device_release_driver+0x28/0x38
[ 1669.997534]  pci_stop_bus_device+0x84/0xb8
[ 1670.001611]  pci_stop_and_remove_bus_device_locked+0x24/0x40
[ 1670.007244]  remove_store+0xfc/0x140
[ 1670.010802]  dev_attr_store+0x44/0x60
[ 1670.014448]  sysfs_kf_write+0x58/0x80
[ 1670.018095]  kernfs_fop_write+0xe8/0x1f0
[ 1670.022000]  __vfs_write+0x60/0x190
[ 1670.025472]  vfs_write+0xac/0x1c0
[ 1670.028771]  ksys_write+0x6c/0xd8
[ 1670.032071]  __arm64_sys_write+0x24/0x30
[ 1670.035977]  el0_svc_common+0x78/0x130
[ 1670.039710]  el0_svc_handler+0x38/0x78
[ 1670.043442]  el0_svc+0x8/0xc

To fix this by set debugfs_dir to NULL after call
debugfs_remove_recursive().
Signed-off-by: NXingui Yang <yangxingui@huawei.com>
Reviewed-by: Nkang fenglong <kangfenglong@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

drivers/scsi/hisi_sas/hisi_sas_main.c

@@ -3559,7 +3559,7 @@ static void hisi_sas_debugfs_create_files(struct hisi_hba *hisi_hba)
 
 	return;
 fail:
-	debugfs_remove_recursive(hisi_hba->debugfs_dir);
+	hisi_sas_debugfs_exit(hisi_hba);
 }
 
 static void hisi_sas_debugfs_snapshot_regs(struct hisi_hba *hisi_hba)
@@ -3741,14 +3741,15 @@ void hisi_sas_debugfs_init(struct hisi_hba *hisi_hba)
 		devm_kfree(dev, hisi_hba->debugfs_port_reg[i]);
 	devm_kfree(dev, hisi_hba->debugfs_global_reg);
 fail_global:
-	debugfs_remove_recursive(hisi_hba->debugfs_dir);
-	dev_dbg(dev, "failed to init debugfs!\n");
+	hisi_sas_debugfs_exit(hisi_hba);
+	dev_info(dev, "failed to init debugfs!\n");
 }
 EXPORT_SYMBOL_GPL(hisi_sas_debugfs_init);
 
 void hisi_sas_debugfs_exit(struct hisi_hba *hisi_hba)
 {
 	debugfs_remove_recursive(hisi_hba->debugfs_dir);
+	hisi_hba->debugfs_dir = NULL;
 }
 EXPORT_SYMBOL_GPL(hisi_sas_debugfs_exit);