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

Steven Rostedt
2026-03-10T14:14:13Z

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 {
>