Re: [PATCH 02/13] tracing: Extract calls to trace_define_common_fields()

[Frederic Weisbecker <fweisbec@gmail.com>]

On Tue, Dec 08, 2009 at 04:03:58PM +0800, Li Zefan wrote:
> >>> --- a/kernel/trace/trace_kprobe.c
> >>> +++ b/kernel/trace/trace_kprobe.c
> >>> @@ -1113,10 +1113,6 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
> >>>  	struct kprobe_trace_entry field;
> >>>  	struct trace_probe *tp = (struct trace_probe *)event_call->data;
> >>>  
> >>> -	ret = trace_define_common_fields(event_call);
> >>> -	if (!ret)
> >>> -		return ret;
> >>> -
> >>>  	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
> >>>  	DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
> >>>  	/* Set argument names as fields */
> >>> @@ -1131,10 +1127,6 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
> >>>  	struct kretprobe_trace_entry field;
> >>>  	struct trace_probe *tp = (struct trace_probe *)event_call->data;
> >>>  
> >>> -	ret = trace_define_common_fields(event_call);
> >>> -	if (!ret)
> >>> -		return ret;
> >>> -
> >>>  	DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
> >>>  	DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
> >>>  	DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
> >> "if (!ret)" is wrong. trace_define_common_fields() returns zero when success.
> >> So "unsigned long, func", "unsigned long, ret_ip" ...etc are NOT "defined"
> >> and filters can not be applied for trace_kprobe.
> >>
> >> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> >>
> > 
> > Oh right!
> > 
> > Ok, I'm queueing this one for the tracing fixes.
> > Thanks!
> > 
> 
> This patch has dependency on the previous patch..So can you queue
> all other patches and send a pull request to Ingo? We're still
> in the early merge window, so those patches should be fine for
> .33.
> 
> And as this patch fixes a bug "acidentally", the changelog
> needs a bit revision.


The problem is that we can't know in advance Linus will take
a second round of tracing features in this merge window.

I'd rather be careful and keep separating tracing fixes and
tracing features.

I'm preparing a separate fix.