Re: [PATCH 6/7] perf data: Fix duplicate field names and avoid reserved keywords

[JÃrÃmie Galarneau]

On Sat, Apr 18, 2015 at 11:50 AM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> From: Wang Nan <wangnan0@xxxxxxxxxx>
>
> Some parameters of syscall tracepoints named as 'nr', 'event', etc.
> When dealing with them, perf convert to ctf meets some problem:
>
>  1. If a parameter with name 'nr', it will duplicate syscall's
>     common field 'nr'. One such syscall is io_submit().
>
>  2. If a parameter with name 'event', it is denied to be inserted
>     because 'event' is a babeltrace keywork. One such syscall is
>     epoll_ctl.

Minor nitpick: "event" is a reserved keyword in the CTF specification
[1], the rule is only enforced by Babeltrace. Also, keywork ->
keyword.

JÃrÃmie

[1] http://diamon.org/docs/ctf/v1.8.2/#specC.1.2

>
> This patch appends '_dupl_X' suffix to avoid problem 1, prepend a '_'
> prefix to avoid problem 2.
>
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> Link: http://lkml.kernel.org/n/tip-4tlh4s2u3xnxr76d1w7qmckb@xxxxxxxxxxxxxx
> [ changed to use format_file::alias ]
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
>  tools/perf/util/data-convert-bt.c | 86 +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 82 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
> index b35c8d6c291d..8eda4ed628e7 100644
> --- a/tools/perf/util/data-convert-bt.c
> +++ b/tools/perf/util/data-convert-bt.c
> @@ -14,6 +14,7 @@
>  #include <babeltrace/ctf-writer/event.h>
>  #include <babeltrace/ctf-writer/event-types.h>
>  #include <babeltrace/ctf-writer/event-fields.h>
> +#include <babeltrace/ctf-ir/utils.h>
>  #include <babeltrace/ctf/events.h>
>  #include <traceevent/event-parse.h>
>  #include "asm/bug.h"
> @@ -184,6 +185,7 @@ static int add_tracepoint_field_value(struct ctf_writer *cw,
>         unsigned int len;
>         int ret;
>
> +       name = fmtf->alias;
>         offset = fmtf->offset;
>         len = fmtf->size;
>         if (flags & FIELD_IS_STRING)
> @@ -567,6 +569,82 @@ static int process_sample_event(struct perf_tool *tool,
>         return cs ? 0 : -1;
>  }
>
> +/* If dup < 0, add a prefix. Else, add _dupl_X suffix. */
> +static char *change_name(char *name, char *orig_name, int dup)
> +{
> +       char *new_name = NULL;
> +       size_t len;
> +
> +       if (!name)
> +               name = orig_name;
> +
> +       if (dup >= 10)
> +               goto out;
> +       /*
> +        * Add '_' prefix to potential keywork.  According to
> +        * Mathieu Desnoyers (https://lkml.org/lkml/2015/1/23/652),
> +        * futher CTF spec updating may require us to use '$'.
> +        */
> +       if (dup < 0)
> +               len = strlen(name) + sizeof("_");
> +       else
> +               len = strlen(orig_name) + sizeof("_dupl_X");
> +
> +       new_name = malloc(len);
> +       if (!new_name)
> +               goto out;
> +
> +       if (dup < 0)
> +               snprintf(new_name, len, "_%s", name);
> +       else
> +               snprintf(new_name, len, "%s_dupl_%d", orig_name, dup);
> +
> +out:
> +       if (name != orig_name)
> +               free(name);
> +       return new_name;
> +}
> +
> +static int event_class_add_field(struct bt_ctf_event_class *event_class,
> +               struct bt_ctf_field_type *type,
> +               struct format_field *field)
> +{
> +       struct bt_ctf_field_type *t = NULL;
> +       char *name;
> +       int dup = 1;
> +       int ret;
> +
> +       /* alias was already assigned */
> +       if (field->alias != field->name)
> +               return bt_ctf_event_class_add_field(event_class, type,
> +                               (char *)field->alias);
> +
> +       name = field->name;
> +
> +       /* If 'name' is a keywork, add prefix. */
> +       if (bt_ctf_validate_identifier(name))
> +               name = change_name(name, field->name, -1);
> +
> +       if (!name) {
> +               pr_err("Failed to fix invalid identifier.");
> +               return -1;
> +       }
> +       while ((t = bt_ctf_event_class_get_field_by_name(event_class, name))) {
> +               bt_ctf_field_type_put(t);
> +               name = change_name(name, field->name, dup++);
> +               if (!name) {
> +                       pr_err("Failed to create dup name for '%s'\n", field->name);
> +                       return -1;
> +               }
> +       }
> +
> +       ret = bt_ctf_event_class_add_field(event_class, type, name);
> +       if (!ret)
> +               field->alias = name;
> +
> +       return ret;
> +}
> +
>  static int add_tracepoint_fields_types(struct ctf_writer *cw,
>                                        struct format_field *fields,
>                                        struct bt_ctf_event_class *event_class)
> @@ -595,14 +673,14 @@ static int add_tracepoint_fields_types(struct ctf_writer *cw,
>                 if (flags & FIELD_IS_ARRAY)
>                         type = bt_ctf_field_type_array_create(type, field->arraylen);
>
> -               ret = bt_ctf_event_class_add_field(event_class, type,
> -                               field->name);
> +               ret = event_class_add_field(event_class, type, field);
>
>                 if (flags & FIELD_IS_ARRAY)
>                         bt_ctf_field_type_put(type);
>
>                 if (ret) {
> -                       pr_err("Failed to add field '%s\n", field->name);
> +                       pr_err("Failed to add field '%s': %d\n",
> +                                       field->name, ret);
>                         return -1;
>                 }
>         }
> @@ -646,7 +724,7 @@ static int add_generic_types(struct ctf_writer *cw, struct perf_evsel *evsel,
>         do {                                                            \
>                 pr2("  field '%s'\n", n);                               \
>                 if (bt_ctf_event_class_add_field(cl, t, n)) {           \
> -                       pr_err("Failed to add field '%s;\n", n);        \
> +                       pr_err("Failed to add field '%s';\n", n);       \
>                         return -1;                                      \
>                 }                                                       \
>         } while (0)
> --
> 1.9.3
>



-- 
JÃrÃmie Galarneau
EfficiOS Inc.
http://www.efficios.com
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