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authorOleg Nesterov <oleg@redhat.com>2013-07-18 18:47:12 (GMT)
committerSteven Rostedt <rostedt@goodmis.org>2013-07-19 01:31:33 (GMT)
commitcd458ba9d5a5592d37b5145e560071e91ea762ac (patch)
treed6a560b077696e68584995ba23e10556fcebcd8d
parent7710b639953b791610f0022a7d52d9801c93b969 (diff)
downloadlinux-cd458ba9d5a5592d37b5145e560071e91ea762ac.tar.xz
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: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/trace_events.c17
1 files changed, 4 insertions, 13 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 76defd9..898f868 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -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