[patch V3 12/32] hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()

From: Thomas Gleixner
Date: Wed May 24 2017 - 04:39:24 EST


From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

etm_probe4() 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 <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx

---
drivers/hwtracing/coresight/coresight-etm4x.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -371,7 +371,7 @@ static void etm4_disable_sysfs(struct co
* 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);

/*
@@ -381,7 +381,7 @@ static void etm4_disable_sysfs(struct co
smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1);

spin_unlock(&drvdata->spinlock);
- put_online_cpus();
+ cpus_read_unlock();

dev_info(drvdata->dev, "ETM tracing disabled\n");
}
@@ -982,7 +982,7 @@ static int etm4_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,
@@ -990,18 +990,18 @@ static int etm4_probe(struct amba_device
dev_err(dev, "ETM arch init failed\n");

if (!etm4_count++) {
- cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING,
- "arm/coresight4:starting",
- etm4_starting_cpu, etm4_dying_cpu);
- ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
- "arm/coresight4:online",
- etm4_online_cpu, NULL);
+ cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,
+ "arm/coresight4:starting",
+ etm4_starting_cpu, etm4_dying_cpu);
+ ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
+ "arm/coresight4:online",
+ etm4_online_cpu, NULL);
if (ret < 0)
goto err_arch_supported;
hp_online = ret;
}

- put_online_cpus();
+ cpus_read_unlock();

if (etm4_arch_supported(drvdata->arch) == false) {
ret = -EINVAL;