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[PATCH] tools lib traceevent: Fix kbuffer_read_at_offset()

Started byNamhyung Kim <namhyung@kernel.org>
First post2016-10-01 12:20 +0200
Last post2016-10-07 00:50 +0200
Articles 6 — 4 participants

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  [PATCH] tools lib traceevent: Fix kbuffer_read_at_offset() Namhyung Kim <namhyung@kernel.org> - 2016-10-01 12:20 +0200
    Re: [PATCH] tools lib traceevent: Fix kbuffer_read_at_offset() Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-10-05 13:40 +0200
    Re: [PATCH] tools lib traceevent: Fix kbuffer_read_at_offset() Steven Rostedt <rostedt@goodmis.org> - 2016-10-05 15:30 +0200
      Re: [PATCH] tools lib traceevent: Fix kbuffer_read_at_offset() Namhyung Kim <namhyung@kernel.org> - 2016-10-07 06:20 +0200
        Re: [PATCH] tools lib traceevent: Fix kbuffer_read_at_offset() Steven Rostedt <rostedt@goodmis.org> - 2016-10-07 16:10 +0200
    [tip:perf/urgent] tools lib traceevent: Fix  kbuffer_read_at_offset() tip-bot for Namhyung Kim <tipbot@zytor.com> - 2016-10-07 00:50 +0200

#1494389 — [PATCH] tools lib traceevent: Fix kbuffer_read_at_offset()

FromNamhyung Kim <namhyung@kernel.org>
Date2016-10-01 12:20 +0200
Subject[PATCH] tools lib traceevent: Fix kbuffer_read_at_offset()
Message-ID<snpyF-71K-9@gated-at.bofh.it>
When it's called with an offset less than or equal to the first event,
it'll return a garbage value since the data is not initialized.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/lib/traceevent/kbuffer-parse.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
index 3bcada3ae05a..65984f1c2974 100644
--- a/tools/lib/traceevent/kbuffer-parse.c
+++ b/tools/lib/traceevent/kbuffer-parse.c
@@ -622,6 +622,7 @@ void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset,
 
 	/* Reset the buffer */
 	kbuffer_load_subbuffer(kbuf, kbuf->subbuffer);
+	data = kbuffer_read_event(kbuf, ts);
 
 	while (kbuf->curr < offset) {
 		data = kbuffer_next_event(kbuf, ts);
-- 
2.10.0

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#1495824

FromArnaldo Carvalho de Melo <acme@kernel.org>
Date2016-10-05 13:40 +0200
Message-ID<soSIi-mA-11@gated-at.bofh.it>
In reply to#1494389
Em Sat, Oct 01, 2016 at 07:17:00PM +0900, Namhyung Kim escreveu:
> When it's called with an offset less than or equal to the first event,
> it'll return a garbage value since the data is not initialized.

Steven, Ack?

- Arnaldo
 
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/lib/traceevent/kbuffer-parse.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
> index 3bcada3ae05a..65984f1c2974 100644
> --- a/tools/lib/traceevent/kbuffer-parse.c
> +++ b/tools/lib/traceevent/kbuffer-parse.c
> @@ -622,6 +622,7 @@ void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset,
>  
>  	/* Reset the buffer */
>  	kbuffer_load_subbuffer(kbuf, kbuf->subbuffer);
> +	data = kbuffer_read_event(kbuf, ts);
>  
>  	while (kbuf->curr < offset) {
>  		data = kbuffer_next_event(kbuf, ts);
> -- 
> 2.10.0

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#1495870

FromSteven Rostedt <rostedt@goodmis.org>
Date2016-10-05 15:30 +0200
Message-ID<soUqK-1wC-15@gated-at.bofh.it>
In reply to#1494389
On Sat,  1 Oct 2016 19:17:00 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> When it's called with an offset less than or equal to the first event,
> it'll return a garbage value since the data is not initialized.

Well, it can at most be equal to (unless offset is negative) because
kbuffer_load_subbuffer() sets kbuf->curr to zero.

But that said, it looks like offset == 0 is buggy.

Acked-by: Steven Rostedt <rostedt@goodmis.org>


-- Steve

> 
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/lib/traceevent/kbuffer-parse.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
> index 3bcada3ae05a..65984f1c2974 100644
> --- a/tools/lib/traceevent/kbuffer-parse.c
> +++ b/tools/lib/traceevent/kbuffer-parse.c
> @@ -622,6 +622,7 @@ void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset,
>  
>  	/* Reset the buffer */
>  	kbuffer_load_subbuffer(kbuf, kbuf->subbuffer);
> +	data = kbuffer_read_event(kbuf, ts);
>  
>  	while (kbuf->curr < offset) {
>  		data = kbuffer_next_event(kbuf, ts);

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#1496989

FromNamhyung Kim <namhyung@kernel.org>
Date2016-10-07 06:20 +0200
Message-ID<spuNz-2X5-1@gated-at.bofh.it>
In reply to#1495870
Hi Steve,

On Wed, Oct 05, 2016 at 09:28:01AM -0400, Steven Rostedt wrote:
> On Sat,  1 Oct 2016 19:17:00 +0900
> Namhyung Kim <namhyung@kernel.org> wrote:
> 
> > When it's called with an offset less than or equal to the first event,
> > it'll return a garbage value since the data is not initialized.
> 
> Well, it can at most be equal to (unless offset is negative) because
> kbuffer_load_subbuffer() sets kbuf->curr to zero.

Actually kbuffer_load_subbuffer() calls kbuf->next_event().  Inside
the function it has a loop updating next valid event.  Sometimes, the
data starts with TIME_EXTEND with value of 0 and the loop skips it
which ended up setting kbuf->curr to 8. :)

I'll take a look it later.

> 
> But that said, it looks like offset == 0 is buggy.
> 
> Acked-by: Steven Rostedt <rostedt@goodmis.org>

Thanks,
Namhyung

> 
> 
> -- Steve
> 
> > 
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > ---
> >  tools/lib/traceevent/kbuffer-parse.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
> > index 3bcada3ae05a..65984f1c2974 100644
> > --- a/tools/lib/traceevent/kbuffer-parse.c
> > +++ b/tools/lib/traceevent/kbuffer-parse.c
> > @@ -622,6 +622,7 @@ void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset,
> >  
> >  	/* Reset the buffer */
> >  	kbuffer_load_subbuffer(kbuf, kbuf->subbuffer);
> > +	data = kbuffer_read_event(kbuf, ts);
> >  
> >  	while (kbuf->curr < offset) {
> >  		data = kbuffer_next_event(kbuf, ts);
>

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#1497172

FromSteven Rostedt <rostedt@goodmis.org>
Date2016-10-07 16:10 +0200
Message-ID<spE0y-1th-3@gated-at.bofh.it>
In reply to#1496989
On Fri, 7 Oct 2016 13:19:08 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> Actually kbuffer_load_subbuffer() calls kbuf->next_event().  Inside
> the function it has a loop updating next valid event.  Sometimes, the
> data starts with TIME_EXTEND with value of 0 and the loop skips it
> which ended up setting kbuf->curr to 8. :)

Right, because kbuffer_read_at_offset() should not return a TIME_EXTEND.

-- Steve

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#1496896 — [tip:perf/urgent] tools lib traceevent: Fix kbuffer_read_at_offset()

Fromtip-bot for Namhyung Kim <tipbot@zytor.com>
Date2016-10-07 00:50 +0200
Subject[tip:perf/urgent] tools lib traceevent: Fix kbuffer_read_at_offset()
Message-ID<sppEd-7qB-19@gated-at.bofh.it>
In reply to#1494389
Commit-ID:  a130347973c408c0e0017a52c74cbc3226c1f0ef
Gitweb:     http://git.kernel.org/tip/a130347973c408c0e0017a52c74cbc3226c1f0ef
Author:     Namhyung Kim <namhyung@kernel.org>
AuthorDate: Sat, 1 Oct 2016 19:17:00 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 5 Oct 2016 11:36:22 -0300

tools lib traceevent: Fix kbuffer_read_at_offset()

When it's called with an offset less than or equal to the first event,
it'll return a garbage value since the data is not initialized.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20161001101700.29146-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/lib/traceevent/kbuffer-parse.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
index 3bcada3..65984f1 100644
--- a/tools/lib/traceevent/kbuffer-parse.c
+++ b/tools/lib/traceevent/kbuffer-parse.c
@@ -622,6 +622,7 @@ void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset,
 
 	/* Reset the buffer */
 	kbuffer_load_subbuffer(kbuf, kbuf->subbuffer);
+	data = kbuffer_read_event(kbuf, ts);
 
 	while (kbuf->curr < offset) {
 		data = kbuffer_next_event(kbuf, ts);

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