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Subject[tip:smp/hotplug] hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()
Commit-ID:  e9f5d63f84febb7e9dfe4e0dc696adf88053fbf2
Gitweb: http://git.kernel.org/tip/e9f5d63f84febb7e9dfe4e0dc696adf88053fbf2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Wed, 24 May 2017 10:15:23 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 26 May 2017 10:10:39 +0200

hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()

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@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170524081547.983493849@linutronix.de

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

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index d1340fb..532adc9 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -371,7 +371,7 @@ static void etm4_disable_sysfs(struct coresight_device *csdev)
* 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 coresight_device *csdev)
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 *adev, const struct amba_id *id)

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 *adev, const struct amba_id *id)
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;
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