* [PATCH 2/6] tracing: event_id_read() uses simple buffer instead of trace_seq
@ 2010-01-19 7:34 Lai Jiangshan
2010-01-20 18:04 ` Frederic Weisbecker
0 siblings, 1 reply; 2+ messages in thread
From: Lai Jiangshan @ 2010-01-19 7:34 UTC (permalink / raw)
To: Steven Rostedt, linux-kernel, Ingo Molnar, Andrew Morton,
Frederic Weisbecker
It seems that struct trace_seq is too heavy for event_id_read().
we use simple buffer instead of struct trace_seq.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 04d3f90..835b370 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -604,23 +604,16 @@ 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[20];
+ int len;
if (*ppos)
return 0;
- s = kmalloc(sizeof(*s), GFP_KERNEL);
- if (!s)
- return -ENOMEM;
+ len = snprintf(buf, sizeof(buf), "%d\n", call->id);
+ len = simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
- trace_seq_init(s);
- trace_seq_printf(s, "%d\n", call->id);
-
- r = simple_read_from_buffer(ubuf, cnt, ppos,
- s->buffer, s->len);
- kfree(s);
- return r;
+ return len;
}
static ssize_t
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 2/6] tracing: event_id_read() uses simple buffer instead of trace_seq
2010-01-19 7:34 [PATCH 2/6] tracing: event_id_read() uses simple buffer instead of trace_seq Lai Jiangshan
@ 2010-01-20 18:04 ` Frederic Weisbecker
0 siblings, 0 replies; 2+ messages in thread
From: Frederic Weisbecker @ 2010-01-20 18:04 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: Steven Rostedt, linux-kernel, Ingo Molnar, Andrew Morton
On Tue, Jan 19, 2010 at 03:34:01PM +0800, Lai Jiangshan wrote:
>
> It seems that struct trace_seq is too heavy for event_id_read().
> we use simple buffer instead of struct trace_seq.
>
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 04d3f90..835b370 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -604,23 +604,16 @@ 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[20];
> + int len;
>
> if (*ppos)
> return 0;
>
> - s = kmalloc(sizeof(*s), GFP_KERNEL);
> - if (!s)
> - return -ENOMEM;
> + len = snprintf(buf, sizeof(buf), "%d\n", call->id);
> + len = simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
>
> - trace_seq_init(s);
> - trace_seq_printf(s, "%d\n", call->id);
> -
> - r = simple_read_from_buffer(ubuf, cnt, ppos,
> - s->buffer, s->len);
> - kfree(s);
> - return r;
> + return len;
> }
>
> static ssize_t
>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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