(If Steven Rostedt accept the previous patch which introduce a priv
 field to 'struct format_field', we can use a relative simple method
 for name conversion. If not , perf must track name conversion by
 itself.)

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.

This patch appends '_dupl_X' suffix to avoid problem 1, prepend a '_'
prefix to avoid problem 2.

Signed-off-by: Wang Nan <wangn...@huawei.com>
---
 tools/perf/util/data-convert-bt.c | 94 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 90 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/data-convert-bt.c 
b/tools/perf/util/data-convert-bt.c
index ddecce8..a94f3bd 100644
--- a/tools/perf/util/data-convert-bt.c
+++ b/tools/perf/util/data-convert-bt.c
@@ -184,6 +184,7 @@ static int add_tracepoint_field_value(struct ctf_writer *cw,
        unsigned int len;
        int ret;
 
+       name = fmtf->priv ? (const char *)fmtf->priv : fmtf->name;
        offset = fmtf->offset;
        len = fmtf->size;
        if (flags & FIELD_IS_STRING)
@@ -567,6 +568,91 @@ 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;
+
+       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 void destroy_field_priv(struct format_field *field)
+{
+       if (!field->priv)
+               return;
+
+       if (field->priv != field->name)
+               free(field->priv);
+
+       field->priv = NULL;
+       field->destroy_priv = NULL;
+}
+
+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;
+
+       if (field->priv)
+               return bt_ctf_event_class_add_field(event_class, type,
+                               (char *)field->priv);
+
+       name = field->name;
+       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 failed, we may hit a keywork. try again with a '_' prefix */
+       if (ret) {
+               name = change_name(name, field->name, -1);
+               if (!name) {
+                       pr_err("Failed to alloc name for '_%s'\n", field->name);
+                       return -1;
+               }
+               ret = bt_ctf_event_class_add_field(event_class, type, name);
+       }
+
+       field->priv = name;
+       field->destroy_priv = destroy_field_priv;
+
+       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 +681,14 @@ 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 +732,7 @@ 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)
-- 
1.8.4

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