Re: [PATCH] leds: trigger: cpu: use cpuhp_setup_state_nocalls() for large CPU counts

Thank you for your contribution! Sashiko AI review found 2 potential issue(=
s) to consider:
- [High] Skipping hotplug startup callbacks during initialization leaves th=
e CPU LED triggers in an incorrect inactive state for all already-online CP=
Us.
- [Low] The commit message description is not capitalized, violating LED su=
bsystem conventions.
--

--- Patch [1]: [PATCH] leds: trigger: cpu: use cpuhp_setup_state_nocalls() =
for large CPU counts ---
commit 2aa3e021f1cce38c0cc7487063d486ab550d6162
Author: Paul Sherman <[email protected]>

leds: trigger: cpu: use cpuhp_setup_state_nocalls() for large CPU counts

This commit changes ledtrig_cpu_init() to use cpuhp_setup_state_nocalls()
instead of cpuhp_setup_state(). This avoids invoking the hotplug callbacks =
for
already-online CPUs at registration time to prevent boot delays on systems
with large CPU counts.

> leds: trigger: cpu: use cpuhp_setup_state_nocalls() for large CPU counts

[Severity: Low]
This isn't a bug, but the commit message description starts with a lowercase
letter. The LED subsystem guidelines mandate: "Always capitalize the descri=
ption
after the subsystem prefix for MFD, LED, and Backlight subsystems."

> diff --git a/drivers/leds/trigger/ledtrig-cpu.c b/drivers/leds/trigger/le=
dtrig-cpu.c
> index 679323c2ccda0..ce75d5f54684c 100644
> --- a/drivers/leds/trigger/ledtrig-cpu.c
> +++ b/drivers/leds/trigger/ledtrig-cpu.c
> @@ -163,7 +163,15 @@ static int __init ledtrig_cpu_init(void)
> =20
>  	register_syscore(&ledtrig_cpu_syscore);
> =20
> -	ret =3D cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "leds/trigger:starting",
> +	/*
> +	 * Use cpuhp_setup_state_nocalls() to avoid invoking ledtrig_online_cpu=
()
> +	 * on every already-online CPU at registration time. On systems with la=
rge
> +	 * CPU counts (e.g. 64-hart RISC-V) cpuhp_setup_state() would serialize
> +	 * callbacks across all online CPUs, causing multi-hundred-second delays
> +	 * during boot. The trigger operates correctly for future hotplug events
> +	 * regardless.
> + 	 */
> +	ret =3D cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "leds/trigger:st=
arting",
> +				ledtrig_online_cpu, ledtrig_prepare_down_cpu);

[Severity: High]
Does skipping the hotplug startup callbacks during initialization leave the=
 CPU
LED triggers in an incorrect inactive state for all already-online CPUs?

By replacing cpuhp_setup_state() with cpuhp_setup_state_nocalls(), the driv=
er
skips invoking ledtrig_online_cpu() for already-online CPUs during registra=
tion.
Because the cpu_trig per-CPU variables and num_active_cpus are zero-initial=
ized,
they remain in the inactive state.

On architectures that do not emit ledtrig_cpu events during idle transition=
s,
these CPUs will never call ledtrig_cpu(CPU_LED_START), so their LEDs will n=
ever
turn on unless they undergo a hotplug offline/online cycle.

--=20
Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260727221607.5216=
[email protected]?part=3D1