[PATCH v4] IB/IPoIB: ibX: failed to create mcg debug file

[Shamir Rabinovitch <shamir.rabinovitch-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

When udev renames the netdev devices, ipoib debugfs entries does not
get renamed. As a result, if subsequent probe of ipoib device reuse the
name then creating a debugfs entry for the new device would fail.

Also, moved ipoib_create_debug_files and ipoib_delete_debug_files as part
of ipoib event handling in order to avoid any race condition between these.

Signed-off-by: Vijay Kumar <vijay.ac.kumar-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Shamir Rabinovitch <shamir.rabinovitch-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>

---
v3->v4:
- Review comment from Mark Bloch <markb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
  Fixed duplicate delete of debug files. Debug files no longer 
  deleted in multiple locations. Debug files are only created/
  deleted as result of NETDEV_XXX events. Verified the events
  work well for ipoib child (vlan) interfaces as well. I do see
  that function 'netdev_wait_allrefs' has the potential to send
  the netdev multiple NETDEV_UNREGISTER events. I am not sure
  if this scenario applicable to ipoib but I added protection
  measures and WARN print in 'ipoib_delete_debug_files' to catch
  and handle such (potential) issue gracefully.
- Review comment from Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
  When the above was fixed, I could then try out what Leon suggested
  and figured that the idea to replace 'ipoib_debugfs_rename'
  with 'ipoib_delete_debug_files' and then 'ipoib_create_debug_files'
  is working fine.
v2->v3:
- Move rev change out of commit message
- Fix typo
v1->v2:
- Review comment from Mark Bloch <markb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
  Verified again and NETDEV_UNREGISTER is called correctly. Debug
  files are removed as expected. Thanks.
- Fix compile warning when CONFIG_INFINIBAND_IPOIB_DEBUG is not set
---

---
 drivers/infiniband/ulp/ipoib/ipoib_fs.c   |    3 ++
 drivers/infiniband/ulp/ipoib/ipoib_main.c |   44 +++++++++++++++++++++++++---
 drivers/infiniband/ulp/ipoib/ipoib_vlan.c |    3 --
 3 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_fs.c b/drivers/infiniband/ulp/ipoib/ipoib_fs.c
index 6bd5740..09396bd 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_fs.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_fs.c
@@ -281,8 +281,11 @@ void ipoib_delete_debug_files(struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
 
+	WARN_ONCE(!priv->mcg_dentry, "null mcg debug file\n");
+	WARN_ONCE(!priv->path_dentry, "null path debug file\n");
 	debugfs_remove(priv->mcg_dentry);
 	debugfs_remove(priv->path_dentry);
+	priv->mcg_dentry = priv->path_dentry = NULL;
 }
 
 int ipoib_register_debugfs(void)
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index b58d9dc..a10a38f 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -108,6 +108,33 @@ struct ipoib_path_iter {
 	.get_net_dev_by_params = ipoib_get_net_dev_by_params,
 };
 
+#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG
+static int ipoib_netdev_event(struct notifier_block *this,
+			      unsigned long event, void *ptr)
+{
+	struct netdev_notifier_info *ni = ptr;
+	struct net_device *dev = ni->dev;
+
+	if (dev->netdev_ops->ndo_open != ipoib_open)
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case NETDEV_REGISTER:
+		ipoib_create_debug_files(dev);
+		break;
+	case NETDEV_CHANGENAME:
+		ipoib_delete_debug_files(dev);
+		ipoib_create_debug_files(dev);
+		break;
+	case NETDEV_UNREGISTER:
+		ipoib_delete_debug_files(dev);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+#endif
+
 int ipoib_open(struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
@@ -1653,8 +1680,6 @@ void ipoib_dev_cleanup(struct net_device *dev)
 
 	ASSERT_RTNL();
 
-	ipoib_delete_debug_files(dev);
-
 	/* Delete any child interfaces first */
 	list_for_each_entry_safe(cpriv, tcpriv, &priv->child_intfs, list) {
 		/* Stop GC on child */
@@ -2072,8 +2097,6 @@ int ipoib_set_dev_features(struct ipoib_dev_priv *priv, struct ib_device *hca)
 		goto register_failed;
 	}
 
-	ipoib_create_debug_files(priv->dev);
-
 	if (ipoib_cm_add_mode_attr(priv->dev))
 		goto sysfs_failed;
 	if (ipoib_add_pkey_attr(priv->dev))
@@ -2088,7 +2111,6 @@ int ipoib_set_dev_features(struct ipoib_dev_priv *priv, struct ib_device *hca)
 	return priv->dev;
 
 sysfs_failed:
-	ipoib_delete_debug_files(priv->dev);
 	unregister_netdev(priv->dev);
 
 register_failed:
@@ -2173,6 +2195,12 @@ static void ipoib_remove_one(struct ib_device *device, void *client_data)
 	kfree(dev_list);
 }
 
+#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG
+static struct notifier_block ipoib_netdev_notifier = {
+	.notifier_call = ipoib_netdev_event,
+};
+#endif
+
 static int __init ipoib_init_module(void)
 {
 	int ret;
@@ -2225,6 +2253,9 @@ static int __init ipoib_init_module(void)
 	if (ret)
 		goto err_client;
 
+#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG
+	register_netdevice_notifier(&ipoib_netdev_notifier);
+#endif
 	return 0;
 
 err_client:
@@ -2242,6 +2273,9 @@ static int __init ipoib_init_module(void)
 
 static void __exit ipoib_cleanup_module(void)
 {
+#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG
+	unregister_netdevice_notifier(&ipoib_netdev_notifier);
+#endif
 	ipoib_netlink_fini();
 	ib_unregister_client(&ipoib_client);
 	ib_sa_unregister_client(&ipoib_sa_client);
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
index a2f9f29..57eadd2 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -87,8 +87,6 @@ int __ipoib_vlan_add(struct ipoib_dev_priv *ppriv, struct ipoib_dev_priv *priv,
 		goto register_failed;
 	}
 
-	ipoib_create_debug_files(priv->dev);
-
 	/* RTNL childs don't need proprietary sysfs entries */
 	if (type == IPOIB_LEGACY_CHILD) {
 		if (ipoib_cm_add_mode_attr(priv->dev))
@@ -109,7 +107,6 @@ int __ipoib_vlan_add(struct ipoib_dev_priv *ppriv, struct ipoib_dev_priv *priv,
 
 sysfs_failed:
 	result = -ENOMEM;
-	ipoib_delete_debug_files(priv->dev);
 	unregister_netdevice(priv->dev);
 
 register_failed:
-- 
1.7.1

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