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Commit 798efc60 authored by Joe Perches's avatar Joe Perches Committed by Greg Kroah-Hartman
Browse files

dev_dbg/dynamic_debug: Update to use printk_emit, optimize stack 



commit c4e00daa
("driver-core: extend dev_printk() to pass structured data")
changed __dev_printk and broke dynamic-debug's ability to control the
dynamic prefix of dev_dbg(dev,..).

commit af7f2158
("drivers-core: make structured logging play nice with dynamic-debug")
made a minimal correction.

The current dynamic debug code uses up to 3 recursion levels via %pV.
This can consume quite a bit of stack.  Directly call printk_emit to
reduce the recursion depth.

These changes include:

dev_dbg:
o Create and use function create_syslog_header to format the syslog
  header for printk_emit uses.
o Call create_syslog_header and neaten __dev_printk
o Make __dev_printk static not global
o Remove include header declaration of __dev_printk
o Remove now unused EXPORT_SYMBOL() of __dev_printk
o Whitespace neatening

dynamic_dev_dbg:
o Remove KERN_DEBUG from dynamic_emit_prefix
o Call create_syslog_header and printk_emit
o Whitespace neatening

Signed-off-by: default avatarJoe Perches <joe@perches.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Tested-by: default avatarJim Cromie <jim.cromie@gmail.com>
Acked-by: default avatarJason Baron <jbaron@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8f949b9a

drivers/base/core.c

+34 −30
Original line number Diff line number Diff line
@@ -1865,26 +1865,19 @@ void device_shutdown(void) 
 */



#ifdef CONFIG_PRINTK

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

		 struct va_format *vaf)

int create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)

{

	char dict[128];

	const char *level_extra = "";

	size_t dictlen = 0;

	const char *subsys;



	if (!dev)

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

	size_t pos = 0;



	if (dev->class)

		subsys = dev->class->name;

	else if (dev->bus)

		subsys = dev->bus->name;

	else

		goto skip;

		return 0;



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

			    "SUBSYSTEM=%s", subsys);

	pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);



	/*

	 * Add device identifier DEVICE=:
@@ -1900,32 +1893,41 @@ int __dev_printk(const char *level, const struct device *dev, 
			c = 'b';

		else

			c = 'c';

		dictlen++;

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

		pos++;

		pos += snprintf(hdr + pos, hdrlen - pos,

				"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,

		pos++;

		pos += snprintf(hdr + pos, hdrlen - pos,

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

	} else {

		dictlen++;

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

		pos++;

		pos += snprintf(hdr + pos, hdrlen - pos,

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

	}

skip:

	if (level[2])

		level_extra = &level[2]; /* skip past KERN_SOH "L" */



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

			   dictlen ? dict : NULL, dictlen,

			   "%s %s: %s%pV",

			   dev_driver_string(dev), dev_name(dev),

			   level_extra, vaf);

	return pos;

}

EXPORT_SYMBOL(create_syslog_header);



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

			struct va_format *vaf)

{

	char hdr[128];

	size_t hdrlen;



	if (!dev)

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



	hdrlen = create_syslog_header(dev, hdr, sizeof(hdr));



	return printk_emit(0, level[1] - '0', hdrlen ? hdr : NULL, hdrlen,

			   "%s %s: %pV",

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

}

EXPORT_SYMBOL(__dev_printk);



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

	       const char *fmt, ...)
@@ -1940,6 +1942,7 @@ int dev_printk(const char *level, const struct device *dev, 
	vaf.va = &args;



	r = __dev_printk(level, dev, &vaf);



	va_end(args);



	return r;
@@ -1959,6 +1962,7 @@ int func(const struct device *dev, const char *fmt, ...) \ 
	vaf.va = &args;						\

								\

	r = __dev_printk(kern_level, dev, &vaf);		\

								\

	va_end(args);						\

								\

	return r;						\

include/linux/device.h

+4 −4
Original line number Diff line number Diff line
@@ -895,12 +895,12 @@ extern const char *dev_driver_string(const struct device *dev); 


#ifdef CONFIG_PRINTK



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

			struct va_format *vaf);

extern int create_syslog_header(const struct device *dev,

				char *hdr, size_t hdrlen);



extern __printf(3, 4)

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

	       const char *fmt, ...)

	;

	       const char *fmt, ...);

extern __printf(2, 3)

int dev_emerg(const struct device *dev, const char *fmt, ...);

extern __printf(2, 3)

lib/dynamic_debug.c

+29 −10
Original line number Diff line number Diff line
@@ -521,11 +521,11 @@ static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf) 
	int pos_after_tid;

	int pos = 0;



	pos += snprintf(buf + pos, remaining(pos), "%s", KERN_DEBUG);

	*buf = '\0';



	if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {

		if (in_interrupt())

			pos += snprintf(buf + pos, remaining(pos), "%s ",

						"<intr>");

			pos += snprintf(buf + pos, remaining(pos), "<intr> ");

		else

			pos += snprintf(buf + pos, remaining(pos), "[%d] ",

					task_pid_vnr(current));
@@ -559,9 +559,13 @@ int __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...) 
	BUG_ON(!fmt);



	va_start(args, fmt);



	vaf.fmt = fmt;

	vaf.va = &args;

	res = printk("%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf);



	res = printk(KERN_DEBUG "%s%pV",

		     dynamic_emit_prefix(descriptor, buf), &vaf);



	va_end(args);



	return res;
@@ -574,15 +578,30 @@ int __dynamic_dev_dbg(struct _ddebug *descriptor, 
	struct va_format vaf;

	va_list args;

	int res;

	char buf[PREFIX_SIZE];



	BUG_ON(!descriptor);

	BUG_ON(!fmt);



	va_start(args, fmt);



	vaf.fmt = fmt;

	vaf.va = &args;

	res = __dev_printk(dynamic_emit_prefix(descriptor, buf), dev, &vaf);



	if (!dev) {

		res = printk(KERN_DEBUG "(NULL device *): %pV", &vaf);

	} else {

		char buf[PREFIX_SIZE];

		char dict[128];

		size_t dictlen;



		dictlen = create_syslog_header(dev, dict, sizeof(dict));



		res = printk_emit(0, 7, dictlen ? dict : NULL, dictlen,

				  "%s%s %s: %pV",

				  dynamic_emit_prefix(descriptor, buf),

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

	}



	va_end(args);



	return res;