Commit a4f98765 authored by John Ogness's avatar John Ogness Committed by Petr Mladek
Browse files

printk: kmsg_dump: remove _nolock() variants 



kmsg_dump_rewind() and kmsg_dump_get_line() are lockless, so there is
no need for _nolock() variants. Remove these functions and switch all
callers of the _nolock() variants.

The functions without _nolock() were chosen because they are already
exported to kernel modules.

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/20210303101528.29901-15-john.ogness@linutronix.de
parent 996e9666

arch/powerpc/xmon/xmon.c

+2 −2
Original line number Diff line number Diff line
@@ -3017,9 +3017,9 @@ dump_log_buf(void) 
	catch_memory_errors = 1;

	sync();



	kmsg_dump_rewind_nolock(&iter);

	kmsg_dump_rewind(&iter);

	xmon_start_pagination();

	while (kmsg_dump_get_line_nolock(&iter, false, buf, sizeof(buf), &len)) {

	while (kmsg_dump_get_line(&iter, false, buf, sizeof(buf), &len)) {

		buf[len] = '\0';

		printf("%s", buf);

	}

include/linux/kmsg_dump.h

+0 −16
Original line number Diff line number Diff line
@@ -57,17 +57,12 @@ struct kmsg_dumper { 
#ifdef CONFIG_PRINTK

void kmsg_dump(enum kmsg_dump_reason reason);



bool kmsg_dump_get_line_nolock(struct kmsg_dump_iter *iter, bool syslog,

			       char *line, size_t size, size_t *len);



bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,

			char *line, size_t size, size_t *len);



bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,

			  char *buf, size_t size, size_t *len_out);



void kmsg_dump_rewind_nolock(struct kmsg_dump_iter *iter);



void kmsg_dump_rewind(struct kmsg_dump_iter *iter);



int kmsg_dump_register(struct kmsg_dumper *dumper);
@@ -80,13 +75,6 @@ static inline void kmsg_dump(enum kmsg_dump_reason reason) 
{

}



static inline bool kmsg_dump_get_line_nolock(struct kmsg_dump_iter *iter,

					     bool syslog, const char *line,

					     size_t size, size_t *len)

{

	return false;

}



static inline bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,

				const char *line, size_t size, size_t *len)

{
@@ -99,10 +87,6 @@ static inline bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog 
	return false;

}



static inline void kmsg_dump_rewind_nolock(struct kmsg_dump_iter *iter)

{

}



static inline void kmsg_dump_rewind(struct kmsg_dump_iter *iter)

{

}

kernel/debug/kdb/kdb_main.c

+4 −4
Original line number Diff line number Diff line
@@ -2126,8 +2126,8 @@ static int kdb_dmesg(int argc, const char **argv) 
		kdb_set(2, setargs);

	}



	kmsg_dump_rewind_nolock(&iter);

	while (kmsg_dump_get_line_nolock(&iter, 1, NULL, 0, NULL))

	kmsg_dump_rewind(&iter);

	while (kmsg_dump_get_line(&iter, 1, NULL, 0, NULL))

		n++;



	if (lines < 0) {
@@ -2159,8 +2159,8 @@ static int kdb_dmesg(int argc, const char **argv) 
	if (skip >= n || skip < 0)

		return 0;



	kmsg_dump_rewind_nolock(&iter);

	while (kmsg_dump_get_line_nolock(&iter, 1, buf, sizeof(buf), &len)) {

	kmsg_dump_rewind(&iter);

	while (kmsg_dump_get_line(&iter, 1, buf, sizeof(buf), &len)) {

		if (skip) {

			skip--;

			continue;

kernel/printk/printk.c

+8 −52
Original line number Diff line number Diff line
@@ -3373,7 +3373,7 @@ void kmsg_dump(enum kmsg_dump_reason reason) 
}



/**

 * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)

 * kmsg_dump_get_line - retrieve one kmsg log line

 * @iter: kmsg dump iterator

 * @syslog: include the "<4>" prefixes

 * @line: buffer to copy the line to
@@ -3388,22 +3388,22 @@ void kmsg_dump(enum kmsg_dump_reason reason) 
 *

 * A return value of FALSE indicates that there are no more records to

 * read.

 *

 * The function is similar to kmsg_dump_get_line(), but grabs no locks.

 */

bool kmsg_dump_get_line_nolock(struct kmsg_dump_iter *iter, bool syslog,

bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,

			char *line, size_t size, size_t *len)

{

	u64 min_seq = latched_seq_read_nolock(&clear_seq);

	struct printk_info info;

	unsigned int line_count;

	struct printk_record r;

	unsigned long flags;

	size_t l = 0;

	bool ret = false;



	if (iter->cur_seq < min_seq)

		iter->cur_seq = min_seq;



	printk_safe_enter_irqsave(flags);

	prb_rec_init_rd(&r, &info, line, size);



	/* Read text or count text lines? */
@@ -3424,40 +3424,11 @@ bool kmsg_dump_get_line_nolock(struct kmsg_dump_iter *iter, bool syslog, 
	iter->cur_seq = r.info->seq + 1;

	ret = true;

out:

	printk_safe_exit_irqrestore(flags);

	if (len)

		*len = l;

	return ret;

}



/**

 * kmsg_dump_get_line - retrieve one kmsg log line

 * @iter: kmsg dump iterator

 * @syslog: include the "<4>" prefixes

 * @line: buffer to copy the line to

 * @size: maximum size of the buffer

 * @len: length of line placed into buffer

 *

 * Start at the beginning of the kmsg buffer, with the oldest kmsg

 * record, and copy one record into the provided buffer.

 *

 * Consecutive calls will return the next available record moving

 * towards the end of the buffer with the youngest messages.

 *

 * A return value of FALSE indicates that there are no more records to

 * read.

 */

bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,

			char *line, size_t size, size_t *len)

{

	unsigned long flags;

	bool ret;



	printk_safe_enter_irqsave(flags);

	ret = kmsg_dump_get_line_nolock(iter, syslog, line, size, len);

	printk_safe_exit_irqrestore(flags);



	return ret;

}

EXPORT_SYMBOL_GPL(kmsg_dump_get_line);



/**
@@ -3550,22 +3521,6 @@ bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog, 
}

EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);



/**

 * kmsg_dump_rewind_nolock - reset the iterator (unlocked version)

 * @iter: kmsg dump iterator

 *

 * Reset the dumper's iterator so that kmsg_dump_get_line() and

 * kmsg_dump_get_buffer() can be called again and used multiple

 * times within the same dumper.dump() callback.

 *

 * The function is similar to kmsg_dump_rewind(), but grabs no locks.

 */

void kmsg_dump_rewind_nolock(struct kmsg_dump_iter *iter)

{

	iter->cur_seq = latched_seq_read_nolock(&clear_seq);

	iter->next_seq = prb_next_seq(prb);

}



/**

 * kmsg_dump_rewind - reset the iterator

 * @iter: kmsg dump iterator
@@ -3579,7 +3534,8 @@ void kmsg_dump_rewind(struct kmsg_dump_iter *iter) 
	unsigned long flags;



	printk_safe_enter_irqsave(flags);

	kmsg_dump_rewind_nolock(iter);

	iter->cur_seq = latched_seq_read_nolock(&clear_seq);

	iter->next_seq = prb_next_seq(prb);

	printk_safe_exit_irqrestore(flags);

}

EXPORT_SYMBOL_GPL(kmsg_dump_rewind);