On Wed, May 24, 2017 at 10:15:22AM +0200, Thomas Gleixner wrote:
> From: Sebastian Andrzej Siewior <bige...@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. Convert *_online_cpus() to the new interfaces while at it.
>
> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
> Signed-off-by: Thomas Gleixner <t...@linutronix.de>
> Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: linux-arm-ker...@lists.infradead.org
Acked-by: Mathieu Poirier <mathieu.poir...@linaro.org>
>
> ---
> drivers/hwtracing/coresight/coresight-etm3x.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> --- a/drivers/hwtracing/coresight/coresight-etm3x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm3x.c
> @@ -587,7 +587,7 @@ static void etm_disable_sysfs(struct cor
> * after cpu online mask indicates the cpu is offline but before the
> * DYING hotplug callback is serviced by the ETM driver.
> */
> - get_online_cpus();
> + cpus_read_lock();
> spin_lock(&drvdata->spinlock);
>
> /*
> @@ -597,7 +597,7 @@ static void etm_disable_sysfs(struct cor
> smp_call_function_single(drvdata->cpu, etm_disable_hw, drvdata, 1);
>
> spin_unlock(&drvdata->spinlock);
> - put_online_cpus();
> + cpus_read_unlock();
>
> dev_info(drvdata->dev, "ETM tracing disabled\n");
> }
> @@ -795,7 +795,7 @@ static int etm_probe(struct amba_device
>
> drvdata->cpu = pdata ? pdata->cpu : 0;
>
> - get_online_cpus();
> + cpus_read_lock();
> etmdrvdata[drvdata->cpu] = drvdata;
>
> if (smp_call_function_single(drvdata->cpu,
> @@ -803,17 +803,17 @@ 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);
> if (ret < 0)
> goto err_arch_supported;
> hp_online = ret;
> }
> - put_online_cpus();
> + cpus_read_unlock();
>
> if (etm_arch_supported(drvdata->arch) == false) {
> ret = -EINVAL;
>
>
