Re: [PATCH v5 1/3] tracing/fprobe: Support comma-separated symbols and :entry/:exit

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 14 Jan 2026 17:13:38 -0500
"Seokwoo Chung (Ryan)" <seokwoo.chung130@gmail.com> wrote:

Missing change log. The subject is the "what" the patch is doing, the
change log needs the "why".

> Signed-off-by: Seokwoo Chung (Ryan) <seokwoo.chung130@gmail.com>
> ---
>  kernel/trace/trace.c        |  4 +--
>  kernel/trace/trace_fprobe.c | 49 ++++++++++++++++++++-----------------
>  kernel/trace/trace_probe.h  |  2 ++
>  3 files changed, 31 insertions(+), 24 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 10cdcc7b194e..73b59d47dfe7 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -5578,8 +5578,8 @@ static const char readme_msg[] =
>  	"\t           r[maxactive][:[<group>/][<event>]] <place> [<args>]\n"
>  #endif
>  #ifdef CONFIG_FPROBE_EVENTS
> -	"\t           f[:[<group>/][<event>]] <func-name>[:entry|:exit] [<args>]\n"
> -	"\t		(single symbols still accept %return)\n"
> +	"\t           f[:[<group>/][<event>]] <func-name>[%return] [<args>]\n"
> +	"\t	      f[:[<group>/][<event>]] <func-list>[:entry|:exit] [<args>]\n" 
>  	"\t           t[:[<group>/][<event>]] <tracepoint> [<args>]\n"
>  #endif
>  #ifdef CONFIG_HIST_TRIGGERS
> diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
> index 5a2a41eea603..1663c341ddb4 100644
> --- a/kernel/trace/trace_fprobe.c
> +++ b/kernel/trace/trace_fprobe.c
> @@ -187,16 +187,23 @@ DEFINE_FREE(tuser_put, struct tracepoint_user *,
>   */
>  struct trace_fprobe {
>  	struct dyn_event	devent;
> -	char			*filter;
> +
>  	struct fprobe		fp;
> -	bool			list_mode;
> -	char			*nofilter;
>  	const char		*symbol;
> -	struct trace_probe	tp;
> +	char			*filter;
> +	char			*nofilter;
> +
>  	bool			tprobe;
>  	struct tracepoint_user	*tuser;
> +
> +	struct trace_probe tp;

Why is this being updated? Nothing in the change log says why?

>  };
>  
> +static inline bool trace_fprobe_has_list(const struct trace_fprobe *tf)
> +{
> +	return tf->filter || tf->nofilter;
> +}
> +
>  static bool is_trace_fprobe(struct dyn_event *ev)
>  {
>  	return ev->ops == &trace_fprobe_ops;
> @@ -847,7 +854,7 @@ static int __register_trace_fprobe(struct trace_fprobe *tf)
>  	 * - list_mode: pass filter/nofilter
>  	 * - single: pass symbol only (legacy)
>  	 */
> -	if (tf->list_mode)
> +	if (trace_fprobe_has_list(tf))
>  		return register_fprobe(&tf->fp, tf->filter, tf->nofilter);
>  	return register_fprobe(&tf->fp, tf->symbol, NULL);
>  }
> @@ -1188,11 +1195,18 @@ static int parse_fprobe_spec(const char *in, bool is_tracepoint,
>  	*base = NULL; *filter = NULL; *nofilter = NULL;
>  	*is_return = false; *list_mode = false;
>  
> -	if (is_tracepoint) {
> +	if (is_tracepoint) 
> +	{
>  		if (strchr(in, ',') || strchr(in, ':'))
> +		{
> +			trace_probe_log_err(0, BAD_TP_NAME);
>  			return -EINVAL;
> +		}
>  		if (strstr(in, "%return"))
> +		{
> +			trace_probe_log_err(p - in, BAD_TP_NAME);
>  			return -EINVAL;
> +		}
>  		for (p = in; *p; p++)
>  			if (!isalnum(*p) && *p != '_')
>  				return -EINVAL;
> @@ -1225,6 +1239,7 @@ static int parse_fprobe_spec(const char *in, bool is_tracepoint,
>  			} else if (!strcmp(p, ":entry")) {
>  				*(char *)p = '\0';
>  			} else {
> +				trace_probe_log_err(p - work, BAD_LIST_SUFFIX);
>  				return -EINVAL;
>  			}
>  		}
> @@ -1233,6 +1248,7 @@ static int parse_fprobe_spec(const char *in, bool is_tracepoint,
>  	list = !!strchr(work, ',');
>  	
>  	if (list && legacy_ret) {
> +		trace_probe_log_err(p - work, BAD_LEGACY_RET);
>  		return -EINVAL;
>  	}
>  
> @@ -1245,12 +1261,9 @@ static int parse_fprobe_spec(const char *in, bool is_tracepoint,
>  
>  	if (list) {
>  		char *tmp = b, *tok;
> -		size_t fsz, nfsz;
>  
> -		fsz = nfsz = strlen(b) + 1;
> -
> -		f = kzalloc(fsz, GFP_KERNEL);
> -		nf = kzalloc(nfsz, GFP_KERNEL);
> +		f = kzalloc(strlen(b) + 1, GFP_KERNEL);
> +		nf = kzalloc(strlen(b) + 1, GFP_KERNEL);
>  		if (!f || !nf)
>  			return -ENOMEM;
>  
> @@ -1261,6 +1274,7 @@ static int parse_fprobe_spec(const char *in, bool is_tracepoint,
>  			if (*tok == '\0') {
>  				trace_probe_log_err(tmp - b - 1, BAD_TP_NAME);
>  				return -EINVAL;
> +			}
>  
>  			if (neg)
>  				tok++;
> @@ -1455,17 +1469,8 @@ static int trace_fprobe_create_internal(int argc, const char *argv[],
>  
>  	/* carry list parsing result into tf */
>  	if (!is_tracepoint) {
> -		tf->list_mode = list_mode;
> -		if (parsed_filter) {
> -			tf->filter = kstrdup(parsed_filter, GFP_KERNEL);
> -			if (!tf->filter)
> -				return -ENOMEM;
> -		}
> -		if (parsed_nofilter) {
> -			tf->nofilter = kstrdup(parsed_nofilter, GFP_KERNEL);
> -			if (!tf->nofilter)
> -				return -ENOMEM;
> -		}
> +		tf->filter = no_free_ptr(parsed_filter);
> +		tf->nofilter = no_free_ptr(parsed_nofilter);
>  	}
>  
>  	/* parse arguments */
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 9fc56c937130..b8b0544eb7cd 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -494,9 +494,11 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
>  	C(BAD_PROBE_ADDR,	"Invalid probed address or symbol"),	\
>  	C(NON_UNIQ_SYMBOL,	"The symbol is not unique"),		\
>  	C(BAD_RETPROBE,		"Retprobe address must be an function entry"), \
> +	C(BAD_LEGACY_RET,	"Legacy %return not allowed with list"), \
>  	C(NO_TRACEPOINT,	"Tracepoint is not found"),		\
>  	C(BAD_TP_NAME,		"Invalid character in tracepoint name"),\
>  	C(BAD_ADDR_SUFFIX,	"Invalid probed address suffix"), \
> +	C(BAD_LIST_SUFFIX,	"Bad list suffix"), \
>  	C(NO_GROUP_NAME,	"Group name is not specified"),		\
>  	C(GROUP_TOO_LONG,	"Group name is too long"),		\
>  	C(BAD_GROUP_NAME,	"Group name must follow the same rules as C identifiers"), \

This definitely needs discussion on why this is needed.

-- Steve