Em Thu, Mar 19, 2015 at 12:36:21PM -0600, David Ahern escreveu:
> Currently the code skips the first field with the expectation that it is
> 'nr'. But older kernels do not have the 'nr' field:
>
> field:int nr; offset:8; size:4; signed:1;
>
> Change perf-trace to drop the field if it exists after parsing the format
> file.
>
> This fixes the off-by-one problem with older kernels (e.g., RHEL6). e.g,
> perf-trace shows this for write:
>
> 1.515 ( 0.006 ms): dd/4245 write(buf: 2</dev/pts/0>, count:
> 140733837536224 ) = 26
>
> where 2 is really the fd, the huge number is really the buf address, etc.
> With this patch you get the more appropriate:
>
> 1.813 ( 0.003 ms): dd/6330 write(fd: 2</dev/pts/0>, buf: 0x7fff22fc81f0,
> count: 25 ) = 25
>
> Signed-off-by: David Ahern <[email protected]>
> ---
> tools/lib/traceevent/event-parse.c | 11 ++++++++---
> tools/lib/traceevent/event-parse.h | 1 +
> tools/perf/builtin-trace.c | 16 +++++++++++++---
> 3 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/tools/lib/traceevent/event-parse.c
> b/tools/lib/traceevent/event-parse.c
> index afe20ed9fac8..e8a29e730dfb 100644
> --- a/tools/lib/traceevent/event-parse.c
> +++ b/tools/lib/traceevent/event-parse.c
> @@ -6228,15 +6228,20 @@ void pevent_ref(struct pevent *pevent)
> pevent->ref_count++;
> }
>
> +void free_format_field(struct format_field *field)
> +{
> + free(field->type);
> + free(field->name);
> + free(field);
> +}
> +
> static void free_format_fields(struct format_field *field)
> {
> struct format_field *next;
>
> while (field) {
> next = field->next;
> - free(field->type);
> - free(field->name);
> - free(field);
> + free_format_field(field);
> field = next;
> }
> }
> diff --git a/tools/lib/traceevent/event-parse.h
> b/tools/lib/traceevent/event-parse.h
> index 5b4efc062320..a548fac646f6 100644
> --- a/tools/lib/traceevent/event-parse.h
> +++ b/tools/lib/traceevent/event-parse.h
> @@ -619,6 +619,7 @@ enum pevent_errno pevent_parse_format(struct pevent
> *pevent,
> const char *buf,
> unsigned long size, const char *sys);
> void pevent_free_format(struct event_format *event);
> +void free_format_field(struct format_field *field);
>
> void *pevent_get_field_raw(struct trace_seq *s, struct event_format *event,
> const char *name, struct pevent_record *record,
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index dcd950ef2fd7..5caeefeda48a 100644
Up to here we should have a separate patch, one that I would like to
have an Acked-by: Rostedt, ok?
But then I don't think we need to do that, i.e. we can just have a
boolean we set at some point to tell that we need to skip the first
entry.
I'll try to cook up a patch for that.
- Arnaldo
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -1442,14 +1442,24 @@ static int syscall__set_arg_fmts(struct syscall *sc)
> struct format_field *field;
> int idx = 0;
>
> - sc->arg_scnprintf = calloc(sc->tp_format->format.nr_fields - 1,
> sizeof(void *));
> + field = sc->tp_format->format.fields;
> + /* drop nr field - not relevant here; does not exist on older kernels */
> + if (field && strcmp(field->name, "nr") == 0) {
> + struct format_field *next = field->next;
> +
> + free_format_field(field);
> + sc->tp_format->format.fields = next;
> + sc->tp_format->format.nr_fields--;
> + }
> +
> + sc->arg_scnprintf = calloc(sc->tp_format->format.nr_fields, sizeof(void
> *));
> if (sc->arg_scnprintf == NULL)
> return -1;
>
> if (sc->fmt)
> sc->arg_parm = sc->fmt->arg_parm;
>
> - for (field = sc->tp_format->format.fields->next; field; field =
> field->next) {
> + for (field = sc->tp_format->format.fields; field; field = field->next) {
> if (sc->fmt && sc->fmt->arg_scnprintf[idx])
> sc->arg_scnprintf[idx] = sc->fmt->arg_scnprintf[idx];
> else if (field->flags & FIELD_IS_POINTER)
> @@ -1547,7 +1557,7 @@ static size_t syscall__scnprintf_args(struct syscall
> *sc, char *bf, size_t size,
> .thread = thread,
> };
>
> - for (field = sc->tp_format->format.fields->next; field;
> + for (field = sc->tp_format->format.fields; field;
> field = field->next, ++arg.idx, bit <<= 1) {
> if (arg.mask & bit)
> continue;
> --
> 2.2.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
