This proposal extends the concept of Linux 2.5's dev_* logging macros to
support network devices.  This feature is intended to simplify error-log
analysis by programs (such as health/configuration monitors) and by
ordinary people who need clearer error reporting.

Two patches are appended.  The first implements the feature described
here.  The second is provided by Scott Feldman, maintainer of the e1000
Ethernet driver, and demonstrates how he could modify that driver to
take advantage of this feature.

BACKGROUND: dev_* MACROS
The existing dev_* macros (dev_dbg, dev_info, dev_warn, dev_err,
dev_printk) are defined in linux/device.h in Linux 2.5.  When used in
place of printk, they enhance the standard printk message by prepending
the driver name and bus ID of the device in question.  These macros take
the usual printk args, plus a pointer to the relevant struct device.
The driver name and bus ID enable the log reader to find the device's
information in sysfs.

netdev_* MACROS
Alan Cox suggested that the dev_* macros could serve as examples for
logging macros in other parts of the kernel.  This proposal defines
analogous macros for network devices.  These new macros are netdev_dbg,
netdev_info, netdev_warn, netdev_err, and netdev_printk.  These macros
take the usual printk args, plus a pointer to the relevant struct
net_device.

The enhanced printk message includes the device's interface name (e.g.,
"eth0").  It also includes the driver name and bus ID of the underlying
device; this makes it easy to associate the message with the network
device's sysfs info.

For example, changing
	printk(KERN_ERR "The EEPROM Checksum Is Not Valid\n");
to
	netdev_err(netdev, "The EEPROM Checksum Is Not Valid\n");
changes the message from
	The EEPROM Checksum Is Not Valid
to something like
	eth0 e1000 40:0b.0: The EEPROM Checksum Is Not Valid
You could find out more about the indicated device by looking in the
directory /sysfs/bus/*/drivers/e1000/40:0b.0.

This proposal adds a new member, dev, to struct net_device that points
to the underlying struct device.  This pointer is typically set in the
driver's probe function.

For simplicity, the netdev_* macros assume that netdev (the net_device
arg) and netdev->name are non-null.  The latter is true as soon as
you call alloc_netdev() for the device.

Jim Keniston
IBM Linux Technology Center
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