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

[Frederic Weisbecker <fweisbec@gmail.com>]

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;