linux-kernel - Re: [PATCH] tracing: Iterate trace

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Date:   Fri, 26 Nov 2021 21:40:55 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] tracing: Iterate trace_[ku]probe objects directly

On Thu, 25 Nov 2021 21:28:52 +0100
Jiri Olsa <jolsa@...hat.com> wrote:

> As suggested by Linus [1] using list_for_each_entry to iterate
> directly trace_[ku]probe objects so we can skip another call to
> container_of in these loops.
> 

This looks very good to me :)

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

Thank you!

> [1] https://lore.kernel.org/r/CAHk-=wjakjw6-rDzDDBsuMoDCqd+9ogifR_EE1F0K-jYek1CdA@mail.gmail.com
> 
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  kernel/trace/trace_kprobe.c | 13 ++++---------
>  kernel/trace/trace_uprobe.c | 23 ++++++++---------------
>  2 files changed, 12 insertions(+), 24 deletions(-)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 33272a7b6912..1cddb42af20c 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -327,11 +327,9 @@ static inline int __enable_trace_kprobe(struct trace_kprobe *tk)
>  
>  static void __disable_trace_kprobe(struct trace_probe *tp)
>  {
> -	struct trace_probe *pos;
>  	struct trace_kprobe *tk;
>  
> -	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -		tk = container_of(pos, struct trace_kprobe, tp);
> +	list_for_each_entry(tk, trace_probe_probe_list(tp), tp.list) {
>  		if (!trace_kprobe_is_registered(tk))
>  			continue;
>  		if (trace_kprobe_is_return(tk))
> @@ -348,7 +346,7 @@ static void __disable_trace_kprobe(struct trace_probe *tp)
>  static int enable_trace_kprobe(struct trace_event_call *call,
>  				struct trace_event_file *file)
>  {
> -	struct trace_probe *pos, *tp;
> +	struct trace_probe *tp;
>  	struct trace_kprobe *tk;
>  	bool enabled;
>  	int ret = 0;
> @@ -369,8 +367,7 @@ static int enable_trace_kprobe(struct trace_event_call *call,
>  	if (enabled)
>  		return 0;
>  
> -	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -		tk = container_of(pos, struct trace_kprobe, tp);
> +	list_for_each_entry(tk, trace_probe_probe_list(tp), tp.list) {
>  		if (trace_kprobe_has_gone(tk))
>  			continue;
>  		ret = __enable_trace_kprobe(tk);
> @@ -559,11 +556,9 @@ static bool trace_kprobe_has_same_kprobe(struct trace_kprobe *orig,
>  					 struct trace_kprobe *comp)
>  {
>  	struct trace_probe_event *tpe = orig->tp.event;
> -	struct trace_probe *pos;
>  	int i;
>  
> -	list_for_each_entry(pos, &tpe->probes, list) {
> -		orig = container_of(pos, struct trace_kprobe, tp);
> +	list_for_each_entry(orig, &tpe->probes, tp.list) {
>  		if (strcmp(trace_kprobe_symbol(orig),
>  			   trace_kprobe_symbol(comp)) ||
>  		    trace_kprobe_offset(orig) != trace_kprobe_offset(comp))
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index f5f0039d31e5..a9a294e6b183 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -409,12 +409,10 @@ static bool trace_uprobe_has_same_uprobe(struct trace_uprobe *orig,
>  					 struct trace_uprobe *comp)
>  {
>  	struct trace_probe_event *tpe = orig->tp.event;
> -	struct trace_probe *pos;
>  	struct inode *comp_inode = d_real_inode(comp->path.dentry);
>  	int i;
>  
> -	list_for_each_entry(pos, &tpe->probes, list) {
> -		orig = container_of(pos, struct trace_uprobe, tp);
> +	list_for_each_entry(orig, &tpe->probes, tp.list) {
>  		if (comp_inode != d_real_inode(orig->path.dentry) ||
>  		    comp->offset != orig->offset)
>  			continue;
> @@ -1075,14 +1073,12 @@ static int trace_uprobe_enable(struct trace_uprobe *tu, filter_func_t filter)
>  
>  static void __probe_event_disable(struct trace_probe *tp)
>  {
> -	struct trace_probe *pos;
>  	struct trace_uprobe *tu;
>  
>  	tu = container_of(tp, struct trace_uprobe, tp);
>  	WARN_ON(!uprobe_filter_is_empty(tu->tp.event->filter));
>  
> -	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -		tu = container_of(pos, struct trace_uprobe, tp);
> +	list_for_each_entry(tu, trace_probe_probe_list(tp), tp.list) {
>  		if (!tu->inode)
>  			continue;
>  
> @@ -1094,7 +1090,7 @@ static void __probe_event_disable(struct trace_probe *tp)
>  static int probe_event_enable(struct trace_event_call *call,
>  			struct trace_event_file *file, filter_func_t filter)
>  {
> -	struct trace_probe *pos, *tp;
> +	struct trace_probe *tp;
>  	struct trace_uprobe *tu;
>  	bool enabled;
>  	int ret;
> @@ -1129,8 +1125,7 @@ static int probe_event_enable(struct trace_event_call *call,
>  	if (ret)
>  		goto err_flags;
>  
> -	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -		tu = container_of(pos, struct trace_uprobe, tp);
> +	list_for_each_entry(tu, trace_probe_probe_list(tp), tp.list) {
>  		ret = trace_uprobe_enable(tu, filter);
>  		if (ret) {
>  			__probe_event_disable(tp);
> @@ -1275,7 +1270,7 @@ static bool trace_uprobe_filter_add(struct trace_uprobe_filter *filter,
>  static int uprobe_perf_close(struct trace_event_call *call,
>  			     struct perf_event *event)
>  {
> -	struct trace_probe *pos, *tp;
> +	struct trace_probe *tp;
>  	struct trace_uprobe *tu;
>  	int ret = 0;
>  
> @@ -1287,8 +1282,7 @@ static int uprobe_perf_close(struct trace_event_call *call,
>  	if (trace_uprobe_filter_remove(tu->tp.event->filter, event))
>  		return 0;
>  
> -	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -		tu = container_of(pos, struct trace_uprobe, tp);
> +	list_for_each_entry(tu, trace_probe_probe_list(tp), tp.list) {
>  		ret = uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
>  		if (ret)
>  			break;
> @@ -1300,7 +1294,7 @@ static int uprobe_perf_close(struct trace_event_call *call,
>  static int uprobe_perf_open(struct trace_event_call *call,
>  			    struct perf_event *event)
>  {
> -	struct trace_probe *pos, *tp;
> +	struct trace_probe *tp;
>  	struct trace_uprobe *tu;
>  	int err = 0;
>  
> @@ -1312,8 +1306,7 @@ static int uprobe_perf_open(struct trace_event_call *call,
>  	if (trace_uprobe_filter_add(tu->tp.event->filter, event))
>  		return 0;
>  
> -	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -		tu = container_of(pos, struct trace_uprobe, tp);
> +	list_for_each_entry(tu, trace_probe_probe_list(tp), tp.list) {
>  		err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
>  		if (err) {
>  			uprobe_perf_close(call, event);
> -- 
> 2.33.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>