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Commit b63f39ea authored by jolsa@redhat.com's avatar jolsa@redhat.com Committed by Steven Rostedt
Browse files

tracing: create generic trace parser 



Create a "trace_parser" that can parse the user space input for
separate words.

struct trace_parser is the descriptor.

Generic "trace_get_user" function that can be a helper to read multiple
words passed in by user space.

Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
LKML-Reference: <1252682969-3366-2-git-send-email-jolsa@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent f81c972d

kernel/trace/trace.c

+106 −0
Original line number Diff line number Diff line
@@ -339,6 +339,112 @@ static struct { 


int trace_clock_id;



/*

 * trace_parser_get_init - gets the buffer for trace parser

 */

int trace_parser_get_init(struct trace_parser *parser, int size)

{

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



	parser->buffer = kmalloc(size, GFP_KERNEL);

	if (!parser->buffer)

		return 1;



	parser->size = size;

	return 0;

}



/*

 * trace_parser_put - frees the buffer for trace parser

 */

void trace_parser_put(struct trace_parser *parser)

{

	kfree(parser->buffer);

}



/*

 * trace_get_user - reads the user input string separated by  space

 * (matched by isspace(ch))

 *

 * For each string found the 'struct trace_parser' is updated,

 * and the function returns.

 *

 * Returns number of bytes read.

 *

 * See kernel/trace/trace.h for 'struct trace_parser' details.

 */

int trace_get_user(struct trace_parser *parser, const char __user *ubuf,

	size_t cnt, loff_t *ppos)

{

	char ch;

	size_t read = 0;

	ssize_t ret;



	if (!*ppos)

		trace_parser_clear(parser);



	ret = get_user(ch, ubuf++);

	if (ret)

		goto out;



	read++;

	cnt--;



	/*

	 * The parser is not finished with the last write,

	 * continue reading the user input without skipping spaces.

	 */

	if (!parser->cont) {

		/* skip white space */

		while (cnt && isspace(ch)) {

			ret = get_user(ch, ubuf++);

			if (ret)

				goto out;

			read++;

			cnt--;

		}



		/* only spaces were written */

		if (isspace(ch)) {

			*ppos += read;

			ret = read;

			goto out;

		}



		parser->idx = 0;

	}



	/* read the non-space input */

	while (cnt && !isspace(ch)) {

		if (parser->idx < parser->size)

			parser->buffer[parser->idx++] = ch;

		else {

			ret = -EINVAL;

			goto out;

		}

		ret = get_user(ch, ubuf++);

		if (ret)

			goto out;

		read++;

		cnt--;

	}



	/* We either got finished input or we have to wait for another call. */

	if (isspace(ch)) {

		parser->buffer[parser->idx] = 0;

		parser->cont = false;

	} else {

		parser->cont = true;

		parser->buffer[parser->idx++] = ch;

	}



	*ppos += read;

	ret = read;



out:

	return ret;

}



ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)

{

	int len;

kernel/trace/trace.h

+35 −0
Original line number Diff line number Diff line
@@ -615,6 +615,41 @@ static inline int ftrace_trace_task(struct task_struct *task) 
}

#endif



/*

 * struct trace_parser - servers for reading the user input separated by spaces

 * @cont: set if the input is not complete - no final space char was found

 * @buffer: holds the parsed user input

 * @idx: user input lenght

 * @size: buffer size

 */

struct trace_parser {

	bool		cont;

	char		*buffer;

	unsigned	idx;

	unsigned	size;

};



static inline bool trace_parser_loaded(struct trace_parser *parser)

{

	return (parser->idx != 0);

}



static inline bool trace_parser_cont(struct trace_parser *parser)

{

	return parser->cont;

}



static inline void trace_parser_clear(struct trace_parser *parser)

{

	parser->cont = false;

	parser->idx = 0;

}



extern int trace_parser_get_init(struct trace_parser *parser, int size);

extern void trace_parser_put(struct trace_parser *parser);

extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,

	size_t cnt, loff_t *ppos);



/*

 * trace_iterator_flags is an enumeration that defines bit

 * positions into trace_flags that controls the output.