ftrace: Create separate t_func_next() to simplify the function / hash logic (5bd84629) · Commits · 戴 / test

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:

Steven Rostedt (VMware) <rostedt@goodmis.org>

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;
		}

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