linux-kernel - [PATCH 3.16 028/134] IB/IPoIB: ibX: failed to create mcg debug file

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Message-ID: <lsq.1503062000.593550768@decadent.org.uk>
Date:   Fri, 18 Aug 2017 14:13:20 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Vijay Kumar" <vijay.ac.kumar@...cle.com>,
        "Doug Ledford" <dledford@...hat.com>,
        "Mark Bloch" <markb@...lanox.com>,
        "Shamir Rabinovitch" <shamir.rabinovitch@...cle.com>
Subject: [PATCH 3.16 028/134] IB/IPoIB: ibX: failed to create mcg debug file

3.16.47-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Shamir Rabinovitch <shamir.rabinovitch@...cle.com>

commit 771a52584096c45e4565e8aabb596eece9d73d61 upstream.

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.

Fixes: 1732b0ef3b3a ([IPoIB] add path record information in debugfs)
Signed-off-by: Vijay Kumar <vijay.ac.kumar@...cle.com>
Signed-off-by: Shamir Rabinovitch <shamir.rabinovitch@...cle.com>
Reviewed-by: Mark Bloch <markb@...lanox.com>
Signed-off-by: Doug Ledford <dledford@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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(-)

--- 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
 {
 	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)
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -98,6 +98,33 @@ static struct ib_client ipoib_client = {
 	.remove = ipoib_remove_one
 };
 
+#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);
@@ -1313,8 +1340,6 @@ void ipoib_dev_cleanup(struct net_device
 
 	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 */
@@ -1620,8 +1645,6 @@ static struct net_device *ipoib_add_port
 		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))
@@ -1636,7 +1659,6 @@ static struct net_device *ipoib_add_port
 	return priv->dev;
 
 sysfs_failed:
-	ipoib_delete_debug_files(priv->dev);
 	unregister_netdev(priv->dev);
 
 register_failed:
@@ -1727,6 +1749,12 @@ static void ipoib_remove_one(struct ib_d
 	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;
@@ -1776,6 +1804,9 @@ 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:
@@ -1793,6 +1824,9 @@ err_fs:
 
 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);
--- a/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_vlan.c
@@ -86,8 +86,6 @@ int __ipoib_vlan_add(struct ipoib_dev_pr
 
 	priv->parent = ppriv->dev;
 
-	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_pr
 
 sysfs_failed:
 	result = -ENOMEM;
-	ipoib_delete_debug_files(priv->dev);
 	unregister_netdevice(priv->dev);
 
 register_failed: