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Subject[tip:smp/hotplug] hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()
Commit-ID:  91e555edde960481085a8a69ac32726a9f6df0c9
Gitweb: http://git.kernel.org/tip/91e555edde960481085a8a69ac32726a9f6df0c9
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:51 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 20 Apr 2017 13:08:53 +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.

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: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170418170553.108514162@linutronix.de
---
drivers/hwtracing/coresight/coresight-etm4x.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index d1340fb..bd3046c 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -990,12 +990,12 @@ 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;
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