linux-kernel - [PATCH 2/2] cpufreq: Remove cpu hotplug callbacks only if they were initialized

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Date:   Thu, 15 Dec 2016 10:00:58 -0500
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     tglx@...utronix.de, bigeasy@...utronix.de, rjw@...ysocki.net,
        viresh.kumar@...aro.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: [PATCH 2/2] cpufreq: Remove cpu hotplug callbacks only if they were initialized

Since cpu hotplug callbacks are requested for CPUHP_AP_ONLINE_DYN state,
successful callback initialization will result in cpuhp_setup_state()
returning a positive value. Therefore acpi_cpufreq_online being zero
indicates that callbacks have not been installed.

This means that acpi_cpufreq_boost_exit() should only remove them if
acpi_cpufreq_online is positive. Trying to call
cpuhp_remove_state_nocalls(0) will cause a BUG().

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
---
 drivers/cpufreq/acpi-cpufreq.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 3a98702..3a2ca0f 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -930,7 +930,7 @@ static void __init acpi_cpufreq_boost_init(void)
 
 static void acpi_cpufreq_boost_exit(void)
 {
-	if (acpi_cpufreq_online >= 0)
+	if (acpi_cpufreq_online > 0)
 		cpuhp_remove_state_nocalls(acpi_cpufreq_online);
 }
 
-- 
1.7.1