ACPI: processor: Avoid NULL pointer dereferences at init time

If there are neither processor objects nor processor device objects
in the ACPI tables, the per-CPU processors table will not be
initialized and attempting to dereference pointers from there will
cause the kernel to crash.  This happens in acpi_processor_ppc_init()
and acpi_thermal_cpufreq_init() after commit d15ce412737a ("ACPI:
cpufreq: Switch to QoS requests instead of cpufreq notifier")
which didn't add the requisite NULL pointer checks in there.

Add the NULL pointer checks to acpi_processor_ppc_init() and
acpi_thermal_cpufreq_init(), and to the corresponding "exit"
routines.

While at it, drop redundant return instructions from
acpi_processor_ppc_init() and acpi_thermal_cpufreq_init().

Fixes: d15ce412737a ("ACPI: cpufreq: Switch to QoS requests instead of cpufreq notifier")
Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

2 files changed, 12 insertions, 8 deletions

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 2261713d1aec..930a49fa4dfc 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -162,21 +162,23 @@ void acpi_processor_ppc_init(int cpu)
         struct acpi_processor *pr = per_cpu(processors, cpu);
         int ret;
 
+        if (!pr)
+                return;
+
         ret = dev_pm_qos_add_request(get_cpu_device(cpu),
                                      &pr->perflib_req, DEV_PM_QOS_MAX_FREQUENCY,
                                      INT_MAX);
-        if (ret < 0) {
+        if (ret < 0)
                 pr_err("Failed to add freq constraint for CPU%d (%d)\n", cpu,
                        ret);
-                return;
-        }
 }
 
 void acpi_processor_ppc_exit(int cpu)
 {
         struct acpi_processor *pr = per_cpu(processors, cpu);
 
-        dev_pm_qos_remove_request(&pr->perflib_req);
+        if (pr)
+                dev_pm_qos_remove_request(&pr->perflib_req);
 }
 
 static int acpi_processor_get_performance_control(struct acpi_processor *pr)
diff --git a/drivers/acpi/processor_thermal.c b/drivers/acpi/processor_thermal.c
index ec2638f1df4f..8227c7dd75b1 100644
--- a/drivers/acpi/processor_thermal.c
+++ b/drivers/acpi/processor_thermal.c
@@ -130,21 +130,23 @@ void acpi_thermal_cpufreq_init(int cpu)
         struct acpi_processor *pr = per_cpu(processors, cpu);
         int ret;
 
+        if (!pr)
+                return;
+
         ret = dev_pm_qos_add_request(get_cpu_device(cpu),
                                      &pr->thermal_req, DEV_PM_QOS_MAX_FREQUENCY,
                                      INT_MAX);
-        if (ret < 0) {
+        if (ret < 0)
                 pr_err("Failed to add freq constraint for CPU%d (%d)\n", cpu,
                        ret);
-                return;
-        }
 }
 
 void acpi_thermal_cpufreq_exit(int cpu)
 {
         struct acpi_processor *pr = per_cpu(processors, cpu);
 
-        dev_pm_qos_remove_request(&pr->thermal_req);
+        if (pr)
+                dev_pm_qos_remove_request(&pr->thermal_req);
 }
 #else                           /* ! CONFIG_CPU_FREQ */
 static int cpufreq_get_max_state(unsigned int cpu)