[PATCH -tip] Return an error when setting a nonexistent tracer

[PATCH -tip] Return an error when setting a nonexistent tracer

[Frederic Weisbecker]

When one try to set a nonexistent tracer, no error is returned
as if the name of the tracer was correct.
We should return -EINVAL.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/trace/trace.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1cd2e81..9b30473 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2384,9 +2384,11 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
 	struct tracer *t;
 	char buf[max_tracer_type_len+1];
 	int i;
+	size_t ret;
 
 	if (cnt > max_tracer_type_len)
 		cnt = max_tracer_type_len;
+	ret = cnt;
 
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
@@ -2402,7 +2404,11 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
 		if (strcmp(t->name, buf) == 0)
 			break;
 	}
-	if (!t || t == current_trace)
+	if (!t) {
+		ret = -EINVAL;
+		goto out;
+	}
+	if (t == current_trace)
 		goto out;
 
 	if (current_trace && current_trace->reset)
@@ -2415,9 +2421,10 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
  out:
 	mutex_unlock(&trace_types_lock);
 
-	filp->f_pos += cnt;
+	if (ret == cnt)
+		filp->f_pos += cnt;
 
-	return cnt;
+	return ret;
 }
 
 static ssize_t

Re: [PATCH -tip] Return an error when setting a nonexistent tracer

[Steven Rostedt]

On Sat, 4 Oct 2008, Frederic Weisbecker wrote:

> When one try to set a nonexistent tracer, no error is returned
> as if the name of the tracer was correct.
> We should return -EINVAL.

Thanks! This has been something I've been meaning to do for a long
time but have never got around to doing it.

( I knew if I waited long enough, someone else would do it ;-)

> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

Acked-by: Steven Rostedt <srostedt@redhat.com>

-- Steve

Re: [PATCH -tip] Return an error when setting a nonexistent tracer

[Ingo Molnar]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Sat, 4 Oct 2008, Frederic Weisbecker wrote:
> 
> > When one try to set a nonexistent tracer, no error is returned
> > as if the name of the tracer was correct.
> > We should return -EINVAL.
> 
> Thanks! This has been something I've been meaning to do for a long
> time but have never got around to doing it.
> 
> ( I knew if I waited long enough, someone else would do it ;-)
> 
> > 
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> 
> Acked-by: Steven Rostedt <srostedt@redhat.com>

applied to tip/tracing/core, thanks!

	Ingo