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Commit c4e00daa authored by Kay Sievers's avatar Kay Sievers Committed by Greg Kroah-Hartman
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driver-core: extend dev_printk() to pass structured data 



Extends dev_printk() to attach a dictionary with a device identifier
and the driver core subsystem name to logged messages, which makes
dev_prink() reliable machine-readable. In addition to the printed
plain text message, it creates these properties:
    SUBSYSTEM=     - the driver-core subsytem name
    DEVICE=
      b12:8        - block dev_t
      c127:3       - char dev_t
      n8           - netdev ifindex
      +sound:card0 - subsystem:devname

Tested-by: default avatarWilliam Douglas <william.douglas@intel.com>
Signed-off-by: default avatarKay Sievers <kay@vrfy.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e11fea92

drivers/base/core.c

+49 −3
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/mutex.h>

#include <linux/async.h>

#include <linux/pm_runtime.h>

#include <linux/netdevice.h>



#include "base.h"

#include "power/power.h"
@@ -1843,15 +1844,60 @@ void device_shutdown(void) 
 */



#ifdef CONFIG_PRINTK



int __dev_printk(const char *level, const struct device *dev,

		 struct va_format *vaf)

{

	char dict[128];

	size_t dictlen = 0;

	const char *subsys;



	if (!dev)

		return printk("%s(NULL device *): %pV", level, vaf);



	return printk("%s%s %s: %pV",

		      level, dev_driver_string(dev), dev_name(dev), vaf);

	if (dev->class)

		subsys = dev->class->name;

	else if (dev->bus)

		subsys = dev->bus->name;

	else

		goto skip;



	dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,

			    "SUBSYSTEM=%s", subsys);



	/*

	 * Add device identifier DEVICE=:

	 *   b12:8         block dev_t

	 *   c127:3        char dev_t

	 *   n8            netdev ifindex

	 *   +sound:card0  subsystem:devname

	 */

	if (MAJOR(dev->devt)) {

		char c;



		if (strcmp(subsys, "block") == 0)

			c = 'b';

		else

			c = 'c';

		dictlen++;

		dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,

				   "DEVICE=%c%u:%u",

				   c, MAJOR(dev->devt), MINOR(dev->devt));

	} else if (strcmp(subsys, "net") == 0) {

		struct net_device *net = to_net_dev(dev);



		dictlen++;

		dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,

				    "DEVICE=n%u", net->ifindex);

	} else {

		dictlen++;

		dictlen += snprintf(dict + dictlen, sizeof(dict) - dictlen,

				    "DEVICE=+%s:%s", subsys, dev_name(dev));

	}

skip:

	return printk_emit(0, level[1] - '0',

			   dictlen ? dict : NULL, dictlen,

			   "%s %s: %pV",

			   dev_driver_string(dev), dev_name(dev), vaf);

}

EXPORT_SYMBOL(__dev_printk);