Commit 74caba7f authored by John Ogness's avatar John Ogness Committed by Petr Mladek
Browse files

printk: move dictionary keys to dev_printk_info 



Dictionaries are only used for SUBSYSTEM and DEVICE properties. The
current implementation stores the property names each time they are
used. This requires more space than otherwise necessary. Also,
because the dictionary entries are currently considered optional,
it cannot be relied upon that they are always available, even if the
writer wanted to store them. These issues will increase should new
dictionary properties be introduced.

Rather than storing the subsystem and device properties in the
dict ring, introduce a struct dev_printk_info with separate fields
to store only the property values. Embed this struct within the
struct printk_info to provide guaranteed availability.

Signed-off-by: default avatarJohn Ogness <john.ogness@linutronix.de>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/87mu1jl6ne.fsf@jogness.linutronix.de
parent cfe2790b

Documentation/admin-guide/kdump/gdbmacros.txt

+33 −40
Original line number Diff line number Diff line
@@ -172,13 +172,13 @@ end 


define dump_record

	set var $desc = $arg0

	if ($argc > 1)

		set var $prev_flags = $arg1

	set var $info = $arg1

	if ($argc > 2)

		set var $prev_flags = $arg2

	else

		set var $prev_flags = 0

	end



	set var $info = &$desc->info

	set var $prefix = 1

	set var $newline = 1
@@ -237,44 +237,36 @@ define dump_record 


	# handle dictionary data



	set var $begin = $desc->dict_blk_lpos.begin % (1U << prb->dict_data_ring.size_bits)

	set var $next = $desc->dict_blk_lpos.next % (1U << prb->dict_data_ring.size_bits)



	# handle data-less record

	if ($begin & 1)

		set var $dict_len = 0

		set var $dict = ""

	set var $dict = &$info->dev_info.subsystem[0]

	set var $dict_len = sizeof($info->dev_info.subsystem)

	if ($dict[0] != '\0')

		printf " SUBSYSTEM="

		set var $idx = 0

		while ($idx < $dict_len)

			set var $c = $dict[$idx]

			if ($c == '\0')

				loop_break

			else

		# handle wrapping data block

		if ($begin > $next)

			set var $begin = 0

		end



		# skip over descriptor id

		set var $begin = $begin + sizeof(long)



		# handle truncated message

		if ($next - $begin < $info->dict_len)

			set var $dict_len = $next - $begin

				if ($c < ' ' || $c >= 127 || $c == '\\')

					printf "\\x%02x", $c

				else

			set var $dict_len = $info->dict_len

					printf "%c", $c

				end



		set var $dict = &prb->dict_data_ring.data[$begin]

			end

			set var $idx = $idx + 1

		end

		printf "\n"

	end



	if ($dict_len > 0)

	set var $dict = &$info->dev_info.device[0]

	set var $dict_len = sizeof($info->dev_info.device)

	if ($dict[0] != '\0')

		printf " DEVICE="

		set var $idx = 0

		set var $line = 1

		while ($idx < $dict_len)

			if ($line)

				printf " "

				set var $line = 0

			end

			set var $c = $dict[$idx]

			if ($c == '\0')

				printf "\n"

				set var $line = 1

				loop_break

			else

				if ($c < ' ' || $c >= 127 || $c == '\\')

					printf "\\x%02x", $c
@@ -288,10 +280,10 @@ define dump_record 
	end

end

document dump_record

	Dump a single record. The first parameter is the descriptor

	sequence number, the second is optional and specifies the

	previous record's flags, used for properly formatting

	continued lines.

	Dump a single record. The first parameter is the descriptor,

	the second parameter is the info, the third parameter is

	optional and specifies the previous record's flags, used for

	properly formatting continued lines.

end



define dmesg
@@ -311,12 +303,13 @@ define dmesg 


	while (1)

		set var $desc = &prb->desc_ring.descs[$id % $desc_count]

		set var $info = &prb->desc_ring.infos[$id % $desc_count]



		# skip non-committed record

		set var $state = 3 & ($desc->state_var.counter >> $desc_flags_shift)

		if ($state == $desc_committed || $state == $desc_finalized)

			dump_record $desc $prev_flags

			set var $prev_flags = $desc->info.flags

			dump_record $desc $info $prev_flags

			set var $prev_flags = $info->flags

		end



		set var $id = ($id + 1) & $id_mask

drivers/base/core.c

+16 −30
Original line number Diff line number Diff line
@@ -3815,22 +3815,21 @@ void device_shutdown(void) 
 */



#ifdef CONFIG_PRINTK

static int

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

static void

set_dev_info(const struct device *dev, struct dev_printk_info *dev_info)

{

	const char *subsys;

	size_t pos = 0;



	memset(dev_info, 0, sizeof(*dev_info));



	if (dev->class)

		subsys = dev->class->name;

	else if (dev->bus)

		subsys = dev->bus->name;

	else

		return 0;

		return;



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

	if (pos >= hdrlen)

		goto overflow;

	strscpy(dev_info->subsystem, subsys, sizeof(dev_info->subsystem));



	/*

	 * Add device identifier DEVICE=:
@@ -3846,41 +3845,28 @@ create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen) 
			c = 'b';

		else

			c = 'c';

		pos++;

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

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

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



		snprintf(dev_info->device, sizeof(dev_info->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);



		pos++;

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

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

		snprintf(dev_info->device, sizeof(dev_info->device),

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

	} else {

		pos++;

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

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

		snprintf(dev_info->device, sizeof(dev_info->device),

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

	}



	if (pos >= hdrlen)

		goto overflow;



	return pos;



overflow:

	dev_WARN(dev, "device/subsystem name too long");

	return 0;

}



int dev_vprintk_emit(int level, const struct device *dev,

		     const char *fmt, va_list args)

{

	char hdr[128];

	size_t hdrlen;

	struct dev_printk_info dev_info;



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

	set_dev_info(dev, &dev_info);



	return vprintk_emit(0, level, hdrlen ? hdr : NULL, hdrlen, fmt, args);

	return vprintk_emit(0, level, &dev_info, fmt, args);

}

EXPORT_SYMBOL(dev_vprintk_emit);

include/linux/dev_printk.h

+8 −0
Original line number Diff line number Diff line
@@ -21,6 +21,14 @@ 


struct device;



#define PRINTK_INFO_SUBSYSTEM_LEN	16

#define PRINTK_INFO_DEVICE_LEN		48



struct dev_printk_info {

	char subsystem[PRINTK_INFO_SUBSYSTEM_LEN];

	char device[PRINTK_INFO_DEVICE_LEN];

};



#ifdef CONFIG_PRINTK



__printf(3, 0) __cold

include/linux/printk.h

+4 −2
Original line number Diff line number Diff line
@@ -158,10 +158,12 @@ static inline void printk_nmi_direct_enter(void) { } 
static inline void printk_nmi_direct_exit(void) { }

#endif /* PRINTK_NMI */



struct dev_printk_info;



#ifdef CONFIG_PRINTK

asmlinkage __printf(5, 0)

asmlinkage __printf(4, 0)

int vprintk_emit(int facility, int level,

		 const char *dict, size_t dictlen,

		 const struct dev_printk_info *dev_info,

		 const char *fmt, va_list args);



asmlinkage __printf(1, 0)

kernel/printk/internal.h

+2 −2
Original line number Diff line number Diff line
@@ -14,9 +14,9 @@ 


extern raw_spinlock_t logbuf_lock;



__printf(5, 0)

__printf(4, 0)

int vprintk_store(int facility, int level,

		  const char *dict, size_t dictlen,

		  const struct dev_printk_info *dev_info,

		  const char *fmt, va_list args);



__printf(1, 0) int vprintk_default(const char *fmt, va_list args);

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