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

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Wed, 13 May 2026 12:40:17 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Tue, 12 May 2026 08:47:50 +0900
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> 
> > On Fri, 8 May 2026 20:26:23 +0800
> > Chen Jun <chenjun102@huawei.com> 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


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>