hwtracing/coresight-etm3x: Use cpuhp_setup_state_nocalls_cpuslocked()

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 <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/20170524081547.889092478@linutronix.de

diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index a51b6b6..93ee8fc 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -587,7 +587,7 @@ static void etm_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);
 
        /*
@@ -597,7 +597,7 @@ static void etm_disable_sysfs(struct coresight_device *csdev)
        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 *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,
@@ -803,17 +803,17 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
                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;