Re: [PATCH v6 3/4] docs: tracing/fprobe: Document list filters and :entry/:exit

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

On Thu,  5 Feb 2026 08:58:41 -0500
"Seokwoo Chung (Ryan)" <seokwoo.chung130@gmail.com> wrote:

> Update fprobe event documentation to describe comma-separated symbol lists,
> exclusions, and explicit suffixes.
> 
> Signed-off-by: Seokwoo Chung (Ryan) <seokwoo.chung130@gmail.com>
> ---
>  Documentation/trace/fprobetrace.rst | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/trace/fprobetrace.rst b/Documentation/trace/fprobetrace.rst
> index b4c2ca3d02c1..bbcfd57f0005 100644
> --- a/Documentation/trace/fprobetrace.rst
> +++ b/Documentation/trace/fprobetrace.rst
> @@ -25,14 +25,18 @@ Synopsis of fprobe-events
>  -------------------------
>  ::
>  
> -  f[:[GRP1/][EVENT1]] SYM [FETCHARGS]                       : Probe on function entry
> -  f[MAXACTIVE][:[GRP1/][EVENT1]] SYM%return [FETCHARGS]     : Probe on function exit
> +  f[:[GRP1/][EVENT1]] SYM[%return] [FETCHARGS]		    : Single function

We also accept wildcard pattern instead of SYM.

  f[:[GRP1/][EVENT1]] (SYM|PATTERN)[%return] [FETCHARGS]	 : Single target

> +  f[:[GRP1/][EVENT1]] SYM[,[!]SYM[,...]][:entry|:exit] [FETCHARGS] :Multiple

Hmm if this is for multiple function, we can not omit event name, so

  f:[GRP1/]EVNET1 SYM[,[!]SYM[,...]][:entry|:exit] [FETCHARGS]   : Multiple function

> +  function

Also, if you put this in the next line, please indent it.

>    t[:[GRP2/][EVENT2]] TRACEPOINT [FETCHARGS]                : Probe on tracepoint
>  
>   GRP1           : Group name for fprobe. If omitted, use "fprobes" for it.
>   GRP2           : Group name for tprobe. If omitted, use "tracepoints" for it.
>   EVENT1         : Event name for fprobe. If omitted, the event name is
> -                  "SYM__entry" or "SYM__exit".
> +		  - For a single literal symbol, the event name is
> +		    "SYM__entry" or "SYM__exit".
> +		  - For a *list or any wildcard*, an explicit [GRP1/][EVENT1] is

an explicit EVENT1 is required. (group name can be omitted)

> +		    required; otherwise the parser rejects it.
>   EVENT2         : Event name for tprobe. If omitted, the event name is
>                    the same as "TRACEPOINT", but if the "TRACEPOINT" starts
>                    with a digit character, "_TRACEPOINT" is used.
> @@ -40,6 +44,13 @@ Synopsis of fprobe-events
>                    can be probed simultaneously, or 0 for the default value
>                    as defined in Documentation/trace/fprobe.rst
>  
> + SYM		: Function name or comma-separated list of symbols.

Doesn't SYM still be a function name? In above synopsis, SYM is an entry of
comma-separated list.

> +		  - SYM prefixed with "!" are exclusions.
> +		  - ":entry" suffix means it probes entry of given symbols
> +		    (default)
> +		  - ":exit" suffix means it probes exit of given symbols.
> +		  - "%return" suffix means it probes exit of SYM (single
> +		    symbol).


And we need PATTERN here.

  PATTERN     : Function name pattern with wildcards (You can use "*" or "?").

Thank you,

>   FETCHARGS      : Arguments. Each probe can have up to 128 args.
>    ARG           : Fetch "ARG" function argument using BTF (only for function
>                    entry or tracepoint.) (\*1)
> -- 
> 2.43.0
> 
> 


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