i40iw: Prevent multiple netdev event notifier registrations

Netdev event notifier registration/de-registration is not
synchronized with a lock and there is a possibility of a
duplicate registration of notifier before the unregister
completes.

Register netdev event notifiers during module init and
de-register them at module exit.

This avoids the need to tie the registration to first netdev
client interface open and de-registration to last client
interface close and the synchronization to achieve it.

This also fixes a crash due to duplicate registration.

BUG: unable to handle kernel paging request at ffffffffa0d60388
IP: [<ffffffff8160f75d>] notifier_call_chain+0x3d/0x70
PGD 190d067 PUD 190e063 PMD 76c840067 PTE 0
Oops: 0000 [#1] SMP
Modules linked in: i40e(OF-) fuse btrfs zlib_deflate raid6_pq xor vfat msdos
[..]
e1000e vxlan ip_tunnel ptp pps_core i2c_core video [last unloaded: i40iw]
CPU: 1 PID: 27101 Comm: modprobe Tainted: GF       W  O--------------   3.10.0-229.el7.x86_64 #1
Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./Q87M-D2H, BIOS F7 01/17/2014
task: ffff88076e8a96c0 ti: ffff8806959c8000 task.ti: ffff8806959c8000
RIP: 0010:[<ffffffff8160f75d>]  [<ffffffff8160f75d>] notifier_call_chain+0x3d/0x70
RSP: 0018:ffff8806959cbb38  EFLAGS: 00010282
RAX: ffffffffa0d60380 RBX: 00000000fffffffd RCX: 0000000000000000
0708] RDX: 0000000000000000 RSI: ffff88081227a000 RDI: 0000000000000002
RBP: ffff8806959cbb60 R08: 0000000000000246 R09: 000000000000700c
R10: ffff88080e16ea40 R11: 00000000000ae8df R12: ffffffffa0d60380
R13: 0000000000000002 R14: ffff88076e738800 R15: 0000000000000000
FS:  00007f604ef4a740(0000) GS:ffff88083e240000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffa0d60388 CR3: 0000000753cd2000 CR4: 00000000001407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
ffffffff819e73a0 0000000000000000 0000000000000002 ffff88076e738800
00000000ffffffff ffff8806959cbba0 ffffffff8109d61d 0000000000000000
0000000000000000 ffff88076e738800 0000000000000000 ffff88076e738800
Call Trace:
[<ffffffff8109d61d>] __blocking_notifier_call_chain+0x4d/0x70
[<ffffffff8109d656>] blocking_notifier_call_chain+0x16/0x20
[<ffffffff8156b9e4>] __inet_del_ifa+0x154/0x2b0
[<ffffffff8156d102>] inetdev_event+0x182/0x530
[<ffffffff8160f76c>] notifier_call_chain+0x4c/0x70
[<ffffffff8109d446>] raw_notifier_call_chain+0x16/0x20
[<ffffffff814f71fd>] call_netdevice_notifiers+0x2d/0x60
[<ffffffff814f8845>] rollback_registered_many+0x105/0x220
[<ffffffff814f89a0>] rollback_registered+0x40/0x70
[<ffffffff814f9c88>] unregister_netdevice_queue+0x48/0x80
[<ffffffff814f9cdc>] unregister_netdev+0x1c/0x30
[<ffffffffa0067139>] i40e_vsi_release+0x2a9/0x2b0 [i40e]
[<ffffffffa00674e8>] i40e_remove+0x128/0x2b0 [i40e]
[<ffffffff813092db>] pci_device_remove+0x3b/0xb0
[<ffffffff813d26ef>] __device_release_driver+0x7f/0xf0
[<ffffffff813d3068>] driver_detach+0xb8/0xc0
[<ffffffff813d22db>] bus_remove_driver+0x9b/0x120
[<ffffffff813d36dc>] driver_unregister+0x2c/0x50
[<ffffffff81307d4c>] pci_unregister_driver+0x2c/0x90
[<ffffffffa008f9d0>] i40e_exit_module+0x10/0x23 [i40e]
[<ffffffff810dad0b>] SyS_delete_module+0x16b/0x2d0
[<ffffffff81013b0c>] ? do_notify_resume+0x9c/0xb0
[<ffffffff81613da9>] system_call_fastpath+0x16/0x1b
Code: e5 41 57 4d 89 c7 41 56 49 89 d6 41 55 49 89 f5 41 54 53 89 cb
75 14 eb 3d 0f 1f 44 00 00 83 eb 01 74 25 4d 85 e4 74 20 4c 89 e0 <4c>
8b 60 08 4c 89 f2 4c 89 ee 48 89 c7 ff 10 4d 85 ff 74 04 41
RIP  [<ffffffff8160f75d>] notifier_call_chain+0x3d/0x70
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/i40iw/i40iw.h

@@ -201,7 +201,6 @@ enum init_completion_state {
 	CEQ_CREATED,
 	ILQ_CREATED,
 	IEQ_CREATED,
-	INET_NOTIFIER,
 	IP_ADDR_REGISTERED,
 	RDMA_DEV_REGISTERED
 };

drivers/infiniband/hw/i40iw/i40iw_main.c

@@ -99,8 +99,6 @@ static struct notifier_block i40iw_net_notifier = {
 	.notifier_call = i40iw_net_event
 };
 
-static atomic_t i40iw_notifiers_registered;
-
 /**
  * i40iw_find_i40e_handler - find a handler given a client info
  * @ldev: pointer to a client info
@@ -1376,11 +1374,20 @@ static enum i40iw_status_code i40iw_initialize_dev(struct i40iw_device *iwdev,
  */
 static void i40iw_register_notifiers(void)
 {
-	if (atomic_inc_return(&i40iw_notifiers_registered) == 1) {
-		register_inetaddr_notifier(&i40iw_inetaddr_notifier);
-		register_inet6addr_notifier(&i40iw_inetaddr6_notifier);
-		register_netevent_notifier(&i40iw_net_notifier);
-	}
+	register_inetaddr_notifier(&i40iw_inetaddr_notifier);
+	register_inet6addr_notifier(&i40iw_inetaddr6_notifier);
+	register_netevent_notifier(&i40iw_net_notifier);
+}
+
+/**
+ * i40iw_unregister_notifiers - unregister tcp ip notifiers
+ */
+
+static void i40iw_unregister_notifiers(void)
+{
+	unregister_netevent_notifier(&i40iw_net_notifier);
+	unregister_inetaddr_notifier(&i40iw_inetaddr_notifier);
+	unregister_inet6addr_notifier(&i40iw_inetaddr6_notifier);
 }
 
 /**
@@ -1467,12 +1474,6 @@ static void i40iw_deinit_device(struct i40iw_device *iwdev)
 		if (!iwdev->reset)
 			i40iw_del_macip_entry(iwdev, (u8)iwdev->mac_ip_table_idx);
 		/* fallthrough */
-	case INET_NOTIFIER:
-		if (!atomic_dec_return(&i40iw_notifiers_registered)) {
-			unregister_netevent_notifier(&i40iw_net_notifier);
-			unregister_inetaddr_notifier(&i40iw_inetaddr_notifier);
-			unregister_inet6addr_notifier(&i40iw_inetaddr6_notifier);
-		}
 		/* fallthrough */
 	case PBLE_CHUNK_MEM:
 		i40iw_destroy_pble_pool(dev, iwdev->pble_rsrc);
@@ -1672,8 +1673,6 @@ static int i40iw_open(struct i40e_info *ldev, struct i40e_client *client)
 			break;
 		iwdev->init_state = PBLE_CHUNK_MEM;
 		iwdev->virtchnl_wq = alloc_ordered_workqueue("iwvch", WQ_MEM_RECLAIM);
-		i40iw_register_notifiers();
-		iwdev->init_state = INET_NOTIFIER;
 		status = i40iw_add_mac_ip(iwdev);
 		if (status)
 			break;
@@ -2023,6 +2022,8 @@ static int __init i40iw_init_module(void)
 	i40iw_client.type = I40E_CLIENT_IWARP;
 	spin_lock_init(&i40iw_handler_lock);
 	ret = i40e_register_client(&i40iw_client);
+	i40iw_register_notifiers();
+
 	return ret;
 }
 
@@ -2034,6 +2035,7 @@ static int __init i40iw_init_module(void)
  */
 static void __exit i40iw_exit_module(void)
 {
+	i40iw_unregister_notifiers();
 	i40e_unregister_client(&i40iw_client);
 }
 

drivers/infiniband/hw/i40iw/i40iw_utils.c

@@ -160,7 +160,7 @@ int i40iw_inetaddr_event(struct notifier_block *notifier,
 		return NOTIFY_DONE;
 
 	iwdev = &hdl->device;
-	if (iwdev->init_state < INET_NOTIFIER)
+	if (iwdev->init_state < IP_ADDR_REGISTERED || iwdev->closing)
 		return NOTIFY_DONE;
 
 	netdev = iwdev->ldev->netdev;
@@ -217,7 +217,7 @@ int i40iw_inet6addr_event(struct notifier_block *notifier,
 		return NOTIFY_DONE;
 
 	iwdev = &hdl->device;
-	if (iwdev->init_state < INET_NOTIFIER)
+	if (iwdev->init_state < IP_ADDR_REGISTERED || iwdev->closing)
 		return NOTIFY_DONE;
 
 	netdev = iwdev->ldev->netdev;
@@ -266,7 +266,7 @@ int i40iw_net_event(struct notifier_block *notifier, unsigned long event, void *
 		if (!iwhdl)
 			return NOTIFY_DONE;
 		iwdev = &iwhdl->device;
-		if (iwdev->init_state < INET_NOTIFIER)
+		if (iwdev->init_state < IP_ADDR_REGISTERED || iwdev->closing)
 			return NOTIFY_DONE;
 		p = (__be32 *)neigh->primary_key;
 		i40iw_copy_ip_ntohl(local_ipaddr, p);