Re: Printing the driver name as part of the netdev watchdog message

[Arjan van de Ven <arjan@infradead.org>]

On Sun, 06 Jul 2008 20:59:05 -0700 (PDT)
David Miller <davem@davemloft.net> wrote:

> 
> Also correct.

ok updated version below; I also added an explicit comment for the
ethtool locking

From: Arjan van de Ven <arjan@linux.intel.com>
Subject: Use WARN_ONCE() in the netdev timeout handler (and print module name)

As suggested by Dave:

This patch adds a function to get the driver name from a struct net_device,
and consequently uses this in the watchdog timeout handler to print as 
part of the message. To make this useful, use WARN_ONCE() so that the
message is part of the ===[ cut here ]=== section, meaning that people
are more likely to report it, and automated warning collection will pick it up.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
 include/linux/netdevice.h |    3 +++
 net/core/dev.c            |   41 ++++++++++++++++++++++++++++++++++++++---
 net/sched/sch_generic.c   |    9 +++++----
 3 files changed, 46 insertions(+), 7 deletions(-)

Index: linux.trees.git/include/linux/netdevice.h
===================================================================
--- linux.trees.git.orig/include/linux/netdevice.h
+++ linux.trees.git/include/linux/netdevice.h
@@ -1514,6 +1514,9 @@ extern void dev_seq_stop(struct seq_file
 extern int netdev_class_create_file(struct class_attribute *class_attr);
 extern void netdev_class_remove_file(struct class_attribute *class_attr);
 
+extern void netdev_drivername(struct net_device *dev, char *buffer, int len);
+
+
 extern void linkwatch_run_queue(void);
 
 extern int netdev_compute_features(unsigned long all, unsigned long one);
Index: linux.trees.git/net/core/dev.c
===================================================================
--- linux.trees.git.orig/net/core/dev.c
+++ linux.trees.git/net/core/dev.c
@@ -3706,10 +3706,8 @@ static void rollback_registered(struct n
 
 	/* Some devices call without registering for initialization unwind. */
 	if (dev->reg_state == NETREG_UNINITIALIZED) {
-		printk(KERN_DEBUG "unregister_netdevice: device %s/%p never "
+		WARN(1, KERN_DEBUG "unregister_netdevice: device %s/%p never "
 				  "was registered\n", dev->name, dev);
-
-		WARN_ON(1);
 		return;
 	}
 
@@ -4554,6 +4552,43 @@ err_name:
 	return -ENOMEM;
 }
 
+void netdev_drivername(struct net_device *dev, char *buffer, int len)
+{
+	struct device_driver *driver;
+	struct device *parent;
+	struct ethtool_drvinfo info;
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+
+	if (len <= 0)
+		return;
+	buffer[0] = 0;
+
+	/*
+	 * Note: in principle ethtool ops need to be called
+	 * with the RTNL mutex held, while this function is called
+	 * from IRQ context. However, get_drvinfo is a special exception
+	 * (confirmed by Dave and Jeff) and doesn't need the mutex.
+	 */
+	if (ops && ops->get_drvinfo) {
+		memset(&info, 0, sizeof(info));
+		info.cmd = ETHTOOL_GDRVINFO;
+		ops->get_drvinfo(dev, &info);
+		if (strlen(info.driver) > 0) {
+			strlcpy(buffer, info.driver, len);
+			return;
+		}
+	}
+
+	parent = dev->dev.parent;
+
+	if (!parent)
+		return;
+
+	driver = parent->driver;
+	if (driver && driver->name)
+		strlcpy(buffer, driver->name, len);
+}
+
 static void __net_exit netdev_exit(struct net *net)
 {
 	kfree(net->dev_name_head);
Index: linux.trees.git/net/sched/sch_generic.c
===================================================================
--- linux.trees.git.orig/net/sched/sch_generic.c
+++ linux.trees.git/net/sched/sch_generic.c
@@ -215,11 +215,12 @@ static void dev_watchdog(unsigned long a
 		    netif_carrier_ok(dev)) {
 			if (netif_queue_stopped(dev) &&
 			    time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) {
-
-				printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n",
-				       dev->name);
+				char drivername[64];
+				netdev_drivername(dev, drivername, 64);
+				WARN_ONCE(1, KERN_INFO
+					"NETDEV WATCHDOG: %s (%s): transmit timed out\n",
+					dev->name, drivername);
 				dev->tx_timeout(dev);
-				WARN_ON_ONCE(1);
 			}
 			if (!mod_timer(&dev->watchdog_timer, round_jiffies(jiffies + dev->watchdog_timeo)))
 				dev_hold(dev);