Re: [PATCH v7 06/10] tracing/probe: Change traceprobe_set_print_fmt() to take a type

[Masami Hiramatsu <mhiramat@kernel.org>]

On Thu, 19 Aug 2021 00:13:27 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
> 
> Instead of a boolean "is_return" have traceprobe_set_print_fmt() take a
> type (currently just PROBE_PRINT_NORMAL and PROBE_PRINT_RETURN). This will
> simplify adding different types. For example, the development of the
> event_probe, will need its own type as it prints an event, and not an IP.
> 
> Link: https://lkml.kernel.org/r/20210817035027.987567364@goodmis.org
> 
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thanks!

> ---
> Changes since v6:
> 
>  - Incorporated more of the ptype enum further into the functions.
> 
>  kernel/trace/trace_kprobe.c |  9 +++++++--
>  kernel/trace/trace_probe.c  | 18 ++++++++++++------
>  kernel/trace/trace_probe.h  |  7 ++++++-
>  kernel/trace/trace_uprobe.c |  8 ++++++--
>  4 files changed, 31 insertions(+), 11 deletions(-)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index ca726c9d0859..c6fe7a6e3f35 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -742,6 +742,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
>  	bool is_return = false;
>  	char *symbol = NULL, *tmp = NULL;
>  	const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
> +	enum probe_print_type ptype;
>  	int maxactive = 0;
>  	long offset = 0;
>  	void *addr = NULL;
> @@ -875,7 +876,8 @@ static int __trace_kprobe_create(int argc, const char *argv[])
>  			goto error;	/* This can be -ENOMEM */
>  	}
>  
> -	ret = traceprobe_set_print_fmt(&tk->tp, is_return);
> +	ptype = is_return ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
> +	ret = traceprobe_set_print_fmt(&tk->tp, ptype);
>  	if (ret < 0)
>  		goto error;
>  
> @@ -1799,6 +1801,7 @@ struct trace_event_call *
>  create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
>  			  bool is_return)
>  {
> +	enum probe_print_type ptype;
>  	struct trace_kprobe *tk;
>  	int ret;
>  	char *event;
> @@ -1822,7 +1825,9 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
>  
>  	init_trace_event_call(tk);
>  
> -	if (traceprobe_set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
> +	ptype = trace_kprobe_is_return(tk) ?
> +		PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
> +	if (traceprobe_set_print_fmt(&tk->tp, ptype) < 0) {
>  		ret = -ENOMEM;
>  		goto error;
>  	}
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 0916a9964719..9c9c83a063b2 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -851,19 +851,25 @@ int traceprobe_update_arg(struct probe_arg *arg)
>  /* When len=0, we just calculate the needed length */
>  #define LEN_OR_ZERO (len ? len - pos : 0)
>  static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
> -			   bool is_return)
> +			   enum probe_print_type ptype)
>  {
>  	struct probe_arg *parg;
>  	int i, j;
>  	int pos = 0;
>  	const char *fmt, *arg;
>  
> -	if (!is_return) {
> +	switch (ptype) {
> +	case PROBE_PRINT_NORMAL:
>  		fmt = "(%lx)";
>  		arg = "REC->" FIELD_STRING_IP;
> -	} else {
> +		break;
> +	case PROBE_PRINT_RETURN:
>  		fmt = "(%lx <- %lx)";
>  		arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
> +		break;
> +	default:
> +		WARN_ON_ONCE(1);
> +		return 0;
>  	}
>  
>  	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
> @@ -912,20 +918,20 @@ static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
>  }
>  #undef LEN_OR_ZERO
>  
> -int traceprobe_set_print_fmt(struct trace_probe *tp, bool is_return)
> +int traceprobe_set_print_fmt(struct trace_probe *tp, enum probe_print_type ptype)
>  {
>  	struct trace_event_call *call = trace_probe_event_call(tp);
>  	int len;
>  	char *print_fmt;
>  
>  	/* First: called with 0 length to calculate the needed length */
> -	len = __set_print_fmt(tp, NULL, 0, is_return);
> +	len = __set_print_fmt(tp, NULL, 0, ptype);
>  	print_fmt = kmalloc(len + 1, GFP_KERNEL);
>  	if (!print_fmt)
>  		return -ENOMEM;
>  
>  	/* Second: actually write the @print_fmt */
> -	__set_print_fmt(tp, print_fmt, len + 1, is_return);
> +	__set_print_fmt(tp, print_fmt, len + 1, ptype);
>  	call->print_fmt = print_fmt;
>  
>  	return 0;
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 42aa084902fa..8adf5f3542a6 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -363,7 +363,12 @@ extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
>  int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
>  				char *buf, int offset);
>  
> -extern int traceprobe_set_print_fmt(struct trace_probe *tp, bool is_return);
> +enum probe_print_type {
> +	PROBE_PRINT_NORMAL,
> +	PROBE_PRINT_RETURN,
> +};
> +
> +extern int traceprobe_set_print_fmt(struct trace_probe *tp, enum probe_print_type ptype);
>  
>  #ifdef CONFIG_PERF_EVENTS
>  extern struct trace_event_call *
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 590bb9a02f8d..09f8ca7f7ba0 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -536,6 +536,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
>  	const char *event = NULL, *group = UPROBE_EVENT_SYSTEM;
>  	char *arg, *filename, *rctr, *rctr_end, *tmp;
>  	char buf[MAX_EVENT_NAME_LEN];
> +	enum probe_print_type ptype;
>  	struct path path;
>  	unsigned long offset, ref_ctr_offset;
>  	bool is_return = false;
> @@ -687,7 +688,8 @@ static int __trace_uprobe_create(int argc, const char **argv)
>  			goto error;
>  	}
>  
> -	ret = traceprobe_set_print_fmt(&tu->tp, is_ret_probe(tu));
> +	ptype = is_ret_probe(tu) ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
> +	ret = traceprobe_set_print_fmt(&tu->tp, ptype);
>  	if (ret < 0)
>  		goto error;
>  
> @@ -1578,6 +1580,7 @@ struct trace_event_call *
>  create_local_trace_uprobe(char *name, unsigned long offs,
>  			  unsigned long ref_ctr_offset, bool is_return)
>  {
> +	enum probe_print_type ptype;
>  	struct trace_uprobe *tu;
>  	struct path path;
>  	int ret;
> @@ -1612,7 +1615,8 @@ create_local_trace_uprobe(char *name, unsigned long offs,
>  	tu->filename = kstrdup(name, GFP_KERNEL);
>  	init_trace_event_call(tu);
>  
> -	if (traceprobe_set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0) {
> +	ptype = is_ret_probe(tu) ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
> +	if (traceprobe_set_print_fmt(&tu->tp, ptype) < 0) {
>  		ret = -ENOMEM;
>  		goto error;
>  	}
> -- 
> 2.30.2


-- 
Masami Hiramatsu <mhiramat@kernel.org>