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Commit 5bd84629 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

ftrace: Create separate t_func_next() to simplify the function / hash logic 



I noticed that if I use dd to read the set_ftrace_filter file that the first
hash command is repeated.

 # cd /sys/kernel/debug/tracing
 # echo schedule > set_ftrace_filter
 # echo do_IRQ >> set_ftrace_filter
 # echo schedule:traceoff >> set_ftrace_filter
 # echo do_IRQ:traceoff >> set_ftrace_filter

 # cat set_ftrace_filter
 schedule
 do_IRQ
 schedule:traceoff:unlimited
 do_IRQ:traceoff:unlimited

 # dd if=set_ftrace_filter bs=1
 schedule
 do_IRQ
 schedule:traceoff:unlimited
 schedule:traceoff:unlimited
 do_IRQ:traceoff:unlimited
 98+0 records in
 98+0 records out
 98 bytes copied, 0.00265011 s, 37.0 kB/s

This is due to the way t_start() calls t_next() as well as the seq_file
calls t_next() and the state is slightly different between the two. Namely,
t_start() will call t_next() with a local "pos" variable.

By separating out the function listing from t_next() into its own function,
we can have better control of outputting the functions and the hash of
triggers. This simplifies the code.

Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 43ff926a

kernel/trace/ftrace.c

+31 −14
Original line number Diff line number Diff line
@@ -3154,22 +3154,12 @@ t_hash_show(struct seq_file *m, struct ftrace_iterator *iter) 
}



static void *

t_next(struct seq_file *m, void *v, loff_t *pos)

t_func_next(struct seq_file *m, loff_t *pos)

{

	struct ftrace_iterator *iter = m->private;

	struct dyn_ftrace *rec = NULL;



	if (unlikely(ftrace_disabled))

		return NULL;



	if (iter->flags & FTRACE_ITER_HASH)

		return t_hash_next(m, pos);



	(*pos)++;

	iter->pos = iter->func_pos = *pos;



	if (iter->flags & FTRACE_ITER_PRINTALL)

		return t_hash_start(m, pos);



 retry:

	if (iter->idx >= iter->pg->index) {
@@ -3192,13 +3182,40 @@ t_next(struct seq_file *m, void *v, loff_t *pos) 
	}



	if (!rec)

		return t_hash_start(m, pos);

		return NULL;



	iter->pos = iter->func_pos = *pos;

	iter->func = rec;



	return iter;

}



static void *

t_next(struct seq_file *m, void *v, loff_t *pos)

{

	struct ftrace_iterator *iter = m->private;

	void *ret;



	if (unlikely(ftrace_disabled))

		return NULL;



	if (iter->flags & FTRACE_ITER_HASH)

		return t_hash_next(m, pos);



	if (iter->flags & FTRACE_ITER_PRINTALL) {

		/* next must increment pos, and t_hash_start does not */

		(*pos)++;

		return t_hash_start(m, pos);

	}



	ret = t_func_next(m, pos);



	if (!ret)

		return t_hash_start(m, pos);



	return ret;

}



static void reset_iter_read(struct ftrace_iterator *iter)

{

	iter->pos = 0;
@@ -3250,13 +3267,13 @@ static void *t_start(struct seq_file *m, loff_t *pos) 
	iter->pg = ftrace_pages_start;

	iter->idx = 0;

	for (l = 0; l <= *pos; ) {

		p = t_next(m, p, &l);

		p = t_func_next(m, &l);

		if (!p)

			break;

	}



	if (!p)

		return NULL;

		return t_hash_start(m, pos);



	return iter;

}