Re: [PATCH 06/18] tracing: Ftrace dynamic ftrace_event_call support

Frederic Weisbecker
2009-08-27T02:56:17Z

On Thu, Aug 27, 2009 at 10:47:24AM +0800, Li Zefan wrote:
> > -int trace_define_field(struct ftrace_event_call *call, const char *type,
> > - const char *name, int offset, int size, int is_signed,
> > +int trace_define_field(struct ftrace_event_call *call, char *type,
> > + char *name, int offset, int size, int is_signed,
> > int filter_type)
>
> I don't see why you remove "const"?

Because kprobes uses dynamically allocated strings as names.
That said, I should turn it back to const, it's indeed more sane.
I don't remember exactly the reason of this. I had to resolve several
conflicts between Masami's patchset and tracing/core, but I did
wrong in this part, indeed.

> > {
> > struct ftrace_event_field *field;
> > @@ -92,9 +92,7 @@ int trace_define_common_fields(struct ftrace_event_call *call)
> > }
> > EXPORT_SYMBOL_GPL(trace_define_common_fields);
>
> ...
>
> > for (i = 0; i < meta->nb_args; i++) {
> > - ret = trace_define_field(call, meta->types[i],
> > - meta->args[i], offset,
> > + ret = trace_define_field(call, (char *)meta->types[i],
> > + (char *)meta->args[i], offset,
>
> This is not good..

Yeah.

>
> > sizeof(unsigned long), 0,
> > FILTER_OTHER);
> > offset += sizeof(unsigned long);
> > @@ -277,13 +277,13 @@ void ftrace_syscall_exit(struct pt_regs *regs, long ret)
> > trace_current_buffer_unlock_commit(event, 0, 0);
> > }
>
> ...
>
> > -int reg_event_syscall_exit(void *ptr)
> > +int reg_event_syscall_exit(struct ftrace_event_call *call)
> > {
> > int ret = 0;
> > int num;
> > char *name;
> >
> > - name = (char *)ptr;
> > + name = (char *)call->data;
>
> nitpick: implicit cast is fine.
>
> > num = syscall_name_to_nr(name);
> > if (num < 0 || num >= FTRACE_SYSCALL_MAX)
> > return -ENOSYS;
> > @@ -342,12 +342,12 @@ int reg_event_syscall_exit(void *ptr)
> > return ret;
> > }
> >
> > -void unreg_event_syscall_exit(void *ptr)
> > +void unreg_event_syscall_exit(struct ftrace_event_call *call)
> > {
> > int num;
> > char *name;
> >
> > - name = (char *)ptr;
> > + name = (char *)call->data;
>
> ditto

Ok, I'll send a delta patch to fix these.

Thanks.

>
> > num = syscall_name_to_nr(name);
> > if (num < 0 || num >= FTRACE_SYSCALL_MAX)
> > return;