Re: [RFC PATCH] trace: Introduce a new filter_pred "caller"

[Steven Rostedt]

Hi Chen,

Do you plan on sending updates to address the comments that Masami and
I have made?

-- Steve


On Thu, 14 May 2026 13:19:01 +0900
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> wrote:

> On Wed, 13 May 2026 12:40:17 -0400
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> 
> > On Tue, 12 May 2026 08:47:50 +0900
> > Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> wrote:
> >   
> > > On Fri, 8 May 2026 20:26:23 +0800
> > > Chen Jun <chenjun102@xxxxxxxxxx> wrote:
> > >   
> > > > Low-level functions have many call paths, and sometimes
> > > > we only care about the calls on a specific call path.
> > > > Add a new filter to filter based on the call stack.
> > > > 
> > > > Usage:
> > > > 1. echo 'caller=="$function_name"' > events/../filter    
> > > 
> > > Thanks for interesting idea :)
> > > 
> > > BTW, we already have "stacktrace". Since this actually checks
> > > stacktrace, not caller, so I think we should reuse it.
> > > Also, I think OP_GLOB is more suitable for this case.
> > > (and more useful)  
> > 
> > Actually, it's not a stack trace, it's a function that is called from other
> > functions. But since "caller" sounds like a direct called function (stack
> > trace of the first instance), I think perhaps it should be "called_within" or
> > something similar. :-/  
> 
> Yeah, what about "callers"?
> 
> > 
> > Also, OP_GLOB can't work because it only works for a single function. At
> > the time of parsing, it finds the function (and should probably error out
> > if there's more than one function with a given name). It then records the
> > start and end address of the function so it only needs to find if one of
> > the entries in the stack trace is between the start and end of the function.  
> 
> Ah, OK. It is just comparing address, not name.
> 
> > 
> > I don't think this is possible with GLOB. We don't want to do a search of
> > the functions when the event is triggered.  
> 
> Agreed.
> 
> Thanks,
> 
> > 
> > -- Steve  
> 
>