Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit cd458ba9 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Steven Rostedt
Browse files

tracing: Do not (ab)use trace_seq in event_id_read() 

event_id_read() has no reason to kmalloc "struct trace_seq"
(more than PAGE_SIZE!), it can use a small buffer instead.

Note: "if (*ppos) return 0" looks strange and even wrong,
simple_read_from_buffer() handles ppos != 0 case corrrectly.

And it seems that almost every user of trace_seq in this file
should be converted too. Unless you use seq_open(), trace_seq
buys nothing compared to the raw buffer, but it needs a bit
more memory and code.

Link: http://lkml.kernel.org/r/20130718184712.GA4786@redhat.com



Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 7710b639

kernel/trace/trace_events.c

+4 −13
Original line number Diff line number Diff line
@@ -947,23 +947,14 @@ static ssize_t 
event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)

{

	struct ftrace_event_call *call = filp->private_data;

	struct trace_seq *s;

	int r;

	char buf[32];

	int len;



	if (*ppos)

		return 0;



	s = kmalloc(sizeof(*s), GFP_KERNEL);

	if (!s)

		return -ENOMEM;



	trace_seq_init(s);

	trace_seq_printf(s, "%d\n", call->event.type);



	r = simple_read_from_buffer(ubuf, cnt, ppos,

				    s->buffer, s->len);

	kfree(s);

	return r;

	len = sprintf(buf, "%d\n", call->event.type);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);

}



static ssize_t