Re: [patch V2 08/24] hwtracing/coresight-etm3x: Use cpuhp_setup_state_nocalls_cpuslocked()

Mathieu Poirier
2017-04-20T15:32:18Z

On Tue, Apr 18, 2017 at 07:04:50PM +0200, Thomas Gleixner wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> etm_probe() holds get_online_cpus() while invoking
> cpuhp_setup_state_nocalls().
>
> cpuhp_setup_state_nocalls() invokes get_online_cpus() as well. This is
> correct, but prevents the conversion of the hotplug locking to a percpu
> rwsem.
>
> Use cpuhp_setup_state_nocalls_cpuslocked() to avoid the nested call.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: linux-arm-kernel@lists.infradead.org
>
> ---
> drivers/hwtracing/coresight/coresight-etm3x.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> --- a/drivers/hwtracing/coresight/coresight-etm3x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm3x.c
> @@ -803,12 +803,12 @@ static int etm_probe(struct amba_device
> dev_err(dev, "ETM arch init failed\n");
>
> if (!etm_count++) {
> - cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING,
> - "arm/coresight:starting",
> - etm_starting_cpu, etm_dying_cpu);
> - ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
> - "arm/coresight:online",
> - etm_online_cpu, NULL);
> + cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,
> + "arm/coresight:starting",
> + etm_starting_cpu, etm_dying_cpu);
> + ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
> + "arm/coresight:online",
> + etm_online_cpu, NULL);

Checkpatch complains about lines being over 80 characters long. It is better to
keep the above or do as follow and make checkpatch happy?

cpuhp_setup_state_nocalls_cpuslocked(
PUHP_AP_ARM_CORESIGHT_STARTING,
"arm/coresight:starting",
etm_starting_cpu, etm_dying_cpu);
ret = cpuhp_setup_state_nocalls_cpuslocked(
CPUHP_AP_ONLINE_DYN,
"arm/coresight:online",
etm_online_cpu, NULL);

Same for coresight-etm4x.c

Thanks,
Mathieu