Re: [RFC][PATCH 06/17 v2] tracing: Add TRACE_DEFINE_ENUM() macro to map enums to their values

Steven Rostedt
2015-04-02T13:27:15Z

On Thu, 2 Apr 2015 16:47:40 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> > +static void update_event_printk(struct ftrace_event_call *call,
> > + struct trace_enum_map *map)
> > +{
> > + char *ptr;
> > + int quote = 0;
> > + int len = strlen(map->enum_string);
> > +
> > + for (ptr = call->print_fmt; *ptr; ptr++) {
> > + if (*ptr == '\\') {
> > + ptr++;
> > + /* paranoid */
> > + if (!*ptr)
> > + break;
> > + continue;
> > + }
> > + if (*ptr == '"') {
> > + quote ^= 1;
> > + continue;
> > + }
> > + if (quote)
> > + continue;
> > + if (isdigit(*ptr)) {
> > + /* skip numbers */
> > + do {
> > + ptr++;
> > + } while (isalnum(*ptr) || *ptr == '_');
> > + /* we went one too many */
>
> Hmm.. it looks like to skip variable name after a number. Shouldn't it be
>
> do { ptr++; } while (isdigit(*ptr));
>
> ?

A variable can not be appended to a number in C. But alpha characters
like 1ULL can be, and they need to be skipped. Hmm, I probably could
remove the check for '_' though.

>
>
> > + ptr--;
> > + continue;
> > + }
> > + if (isalpha(*ptr) || *ptr == '_') {
> > + if (strncmp(map->enum_string, ptr, len) == 0 &&
> > + !isalnum(ptr[len]) && ptr[len] != '_') {
> > + ptr = enum_replace(ptr, map, len);
> > + /* Hmm, enum string smaller than value */
> > + if (WARN_ON_ONCE(!ptr))
> > + return;
> > + continue;
>
> I guess it also needs to decrease the ptr here.

I thought about this when writing it and realized that it just replaced
a variable and two variables can not be bumped against each other.
There must be something in between them, and we can skip whatever that
something is.

I could add a comment about that.

>
>
> > + }
> > + do {
> > + ptr++;
> > + } while (isalnum(*ptr) || *ptr == '_');
> > + /* we went one too many */
> > + ptr--;
> > + continue;
> > + }
> > + }
> > +}
> > +
> > +void trace_event_enum_update(struct trace_enum_map *map, int len)
> > +{
> > + struct ftrace_event_call *call, *p;
> > + const char *last_system = NULL;
> > + int last_i;
> > + int i;
> > +
> > + down_write(&trace_event_sem);
> > + list_for_each_entry_safe(call, p, &ftrace_events, list) {
> > + /* events are usually grouped together with systems */
> > + if (!last_system || call->class->system != last_system)
> > + last_i = 0;
>
> I think it needs to update the last_system here.

Ouch, yeah you're right!

Will fix.

Thanks,

-- Steve