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[PATCH 15/61] trace: Prefer IS_ERR_OR_NULL over manual NULL check

Philipp Hahn posted 61 patches 4 weeks, 1 day ago
[PATCH 15/61] trace: Prefer IS_ERR_OR_NULL over manual NULL check
Posted by Philipp Hahn 4 weeks, 1 day ago 
Prefer using IS_ERR_OR_NULL() over using IS_ERR() and a manual NULL
check.

Change generated with coccinelle.

To: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-kernel@vger.kernel.org
Signed-off-by: Philipp Hahn <phahn-oss@avm.de>
---
 kernel/trace/fprobe.c                | 2 +-
 kernel/trace/kprobe_event_gen_test.c | 2 +-
 kernel/trace/trace_events_hist.c     | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index dcadf1d23b8a31f571392d0c49cbd22df1716b4f..a94ce810d83b90f55d1178a9bd29c78fd068df4c 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -607,7 +607,7 @@ static int fprobe_module_callback(struct notifier_block *nb,
 	do {
 		rhashtable_walk_start(&iter);
 
-		while ((node = rhashtable_walk_next(&iter)) && !IS_ERR(node))
+		while (!IS_ERR_OR_NULL((node = rhashtable_walk_next(&iter))))
 			fprobe_remove_node_in_module(mod, node, &alist);
 
 		rhashtable_walk_stop(&iter);
diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
index 5a4b722b50451bfdee42769a6d3be39c055690d1..a1735ca273f0b756aa1fcfcdab30ddad9bc51c5f 100644
--- a/kernel/trace/kprobe_event_gen_test.c
+++ b/kernel/trace/kprobe_event_gen_test.c
@@ -75,7 +75,7 @@ static struct trace_event_file *gen_kretprobe_test;
 
 static bool trace_event_file_is_valid(struct trace_event_file *input)
 {
-	return input && !IS_ERR(input);
+	return !IS_ERR_OR_NULL(input);
 }
 
 /*
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 73ea180cad555898693e92ee397a1c9493c7c167..59df215e1dfd9349eca1c0823ed709ec7285f766 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -3973,7 +3973,7 @@ trace_action_create_field_var(struct hist_trigger_data *hist_data,
 	 */
 	field_var = create_target_field_var(hist_data, system, event, var);
 
-	if (field_var && !IS_ERR(field_var)) {
+	if (!IS_ERR_OR_NULL(field_var)) {
 		save_field_var(hist_data, field_var);
 		hist_field = field_var->var;
 	} else {

-- 
2.43.0
Re: [PATCH 15/61] trace: Prefer IS_ERR_OR_NULL over manual NULL check
Posted by Steven Rostedt 4 weeks, 1 day ago 
On Tue, 10 Mar 2026 12:48:41 +0100
Philipp Hahn <phahn-oss@avm.de> wrote:

> Prefer using IS_ERR_OR_NULL() over using IS_ERR() and a manual NULL
> check.

Why?

> 
> Change generated with coccinelle.
> 
> To: Steven Rostedt <rostedt@goodmis.org>
> To: Masami Hiramatsu <mhiramat@kernel.org>
> To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-trace-kernel@vger.kernel.org
> Signed-off-by: Philipp Hahn <phahn-oss@avm.de>
> ---
>  kernel/trace/fprobe.c                | 2 +-
>  kernel/trace/kprobe_event_gen_test.c | 2 +-
>  kernel/trace/trace_events_hist.c     | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> index dcadf1d23b8a31f571392d0c49cbd22df1716b4f..a94ce810d83b90f55d1178a9bd29c78fd068df4c 100644
> --- a/kernel/trace/fprobe.c
> +++ b/kernel/trace/fprobe.c
> @@ -607,7 +607,7 @@ static int fprobe_module_callback(struct notifier_block *nb,
>  	do {
>  		rhashtable_walk_start(&iter);
>  
> -		while ((node = rhashtable_walk_next(&iter)) && !IS_ERR(node))
> +		while (!IS_ERR_OR_NULL((node = rhashtable_walk_next(&iter))))

Ug, No!

That looks so much worse than the original.

-- Steve

>  			fprobe_remove_node_in_module(mod, node, &alist);
>  
>  		rhashtable_walk_stop(&iter);
> diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
> index 5a4b722b50451bfdee42769a6d3be39c055690d1..a1735ca273f0b756aa1fcfcdab30ddad9bc51c5f 100644
> --- a/kernel/trace/kprobe_event_gen_test.c
> +++ b/kernel/trace/kprobe_event_gen_test.c
> @@ -75,7 +75,7 @@ static struct trace_event_file *gen_kretprobe_test;
>  
>  static bool trace_event_file_is_valid(struct trace_event_file *input)
>  {
> -	return input && !IS_ERR(input);
> +	return !IS_ERR_OR_NULL(input);
>  }
>  
>  /*
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 73ea180cad555898693e92ee397a1c9493c7c167..59df215e1dfd9349eca1c0823ed709ec7285f766 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -3973,7 +3973,7 @@ trace_action_create_field_var(struct hist_trigger_data *hist_data,
>  	 */
>  	field_var = create_target_field_var(hist_data, system, event, var);
>  
> -	if (field_var && !IS_ERR(field_var)) {
> +	if (!IS_ERR_OR_NULL(field_var)) {
>  		save_field_var(hist_data, field_var);
>  		hist_field = field_var->var;
>  	} else {
>
Re: [PATCH 15/61] trace: Prefer IS_ERR_OR_NULL over manual NULL check
Posted by Masami Hiramatsu (Google) 4 weeks, 1 day ago 
On Tue, 10 Mar 2026 10:07:50 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Tue, 10 Mar 2026 12:48:41 +0100
> Philipp Hahn <phahn-oss@avm.de> wrote:
> 
> > Prefer using IS_ERR_OR_NULL() over using IS_ERR() and a manual NULL
> > check.
> 
> Why?
> 
> > 
> > Change generated with coccinelle.
> > 
> > To: Steven Rostedt <rostedt@goodmis.org>
> > To: Masami Hiramatsu <mhiramat@kernel.org>
> > To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> > Cc: linux-kernel@vger.kernel.org
> > Cc: linux-trace-kernel@vger.kernel.org
> > Signed-off-by: Philipp Hahn <phahn-oss@avm.de>
> > ---
> >  kernel/trace/fprobe.c                | 2 +-
> >  kernel/trace/kprobe_event_gen_test.c | 2 +-
> >  kernel/trace/trace_events_hist.c     | 2 +-
> >  3 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> > index dcadf1d23b8a31f571392d0c49cbd22df1716b4f..a94ce810d83b90f55d1178a9bd29c78fd068df4c 100644
> > --- a/kernel/trace/fprobe.c
> > +++ b/kernel/trace/fprobe.c
> > @@ -607,7 +607,7 @@ static int fprobe_module_callback(struct notifier_block *nb,
> >  	do {
> >  		rhashtable_walk_start(&iter);
> >  
> > -		while ((node = rhashtable_walk_next(&iter)) && !IS_ERR(node))
> > +		while (!IS_ERR_OR_NULL((node = rhashtable_walk_next(&iter))))
> 
> Ug, No!
> 
> That looks so much worse than the original.

Hmm, now IS_ERR_OR_NULL() is an inline function, so it is safe.
But if you want to use IS_ERR_OR_NULL() here, it will be better something like

node = rhashtable_walk_next(&iter);
while (!IS_ERR_OR_NULL(node)) {
	fprobe_remove_node_in_module(mod, node, &alist);
	node = rhashtable_walk_next(&iter);
}

Thanks,

> 
> -- Steve
> 
> >  			fprobe_remove_node_in_module(mod, node, &alist);
> >  
> >  		rhashtable_walk_stop(&iter);
> > diff --git a/kernel/trace/kprobe_event_gen_test.c b/kernel/trace/kprobe_event_gen_test.c
> > index 5a4b722b50451bfdee42769a6d3be39c055690d1..a1735ca273f0b756aa1fcfcdab30ddad9bc51c5f 100644
> > --- a/kernel/trace/kprobe_event_gen_test.c
> > +++ b/kernel/trace/kprobe_event_gen_test.c
> > @@ -75,7 +75,7 @@ static struct trace_event_file *gen_kretprobe_test;
> >  
> >  static bool trace_event_file_is_valid(struct trace_event_file *input)
> >  {
> > -	return input && !IS_ERR(input);
> > +	return !IS_ERR_OR_NULL(input);
> >  }
> >  
> >  /*
> > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> > index 73ea180cad555898693e92ee397a1c9493c7c167..59df215e1dfd9349eca1c0823ed709ec7285f766 100644
> > --- a/kernel/trace/trace_events_hist.c
> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -3973,7 +3973,7 @@ trace_action_create_field_var(struct hist_trigger_data *hist_data,
> >  	 */
> >  	field_var = create_target_field_var(hist_data, system, event, var);
> >  
> > -	if (field_var && !IS_ERR(field_var)) {
> > +	if (!IS_ERR_OR_NULL(field_var)) {
> >  		save_field_var(hist_data, field_var);
> >  		hist_field = field_var->var;
> >  	} else {
> > 
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>
Re: [PATCH 15/61] trace: Prefer IS_ERR_OR_NULL over manual NULL check
Posted by Steven Rostedt 4 weeks ago 
On Wed, 11 Mar 2026 14:13:32 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> Hmm, now IS_ERR_OR_NULL() is an inline function, so it is safe.
> But if you want to use IS_ERR_OR_NULL() here, it will be better something like
> 
> node = rhashtable_walk_next(&iter);
> while (!IS_ERR_OR_NULL(node)) {
> 	fprobe_remove_node_in_module(mod, node, &alist);
> 	node = rhashtable_walk_next(&iter);
> }

But now you need to have a duplicate code in order to acquire "node"

I think the patch just makes the code worse.

-- Steve
Re: [PATCH 15/61] trace: Prefer IS_ERR_OR_NULL over manual NULL check
Posted by Geert Uytterhoeven 4 weeks ago 
Hi Steven,

On Wed, 11 Mar 2026 at 15:03, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Wed, 11 Mar 2026 14:13:32 +0900
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
>
> > Hmm, now IS_ERR_OR_NULL() is an inline function, so it is safe.
> > But if you want to use IS_ERR_OR_NULL() here, it will be better something like
> >
> > node = rhashtable_walk_next(&iter);
> > while (!IS_ERR_OR_NULL(node)) {
> >       fprobe_remove_node_in_module(mod, node, &alist);
> >       node = rhashtable_walk_next(&iter);
> > }
>
> But now you need to have a duplicate code in order to acquire "node"
>
> I think the patch just makes the code worse.

Obviously we need a new for_each_*() helper hiding all the gory internals?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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