cpufreq: cpufreq-cpu0: use RCU locks around usage of OPP

OPP pointer is RCU protected, hence after finding it, de-reference
also should be protected with the same RCU context else the OPP
pointer may become invalid.

Reported-by: Jack Mitchell <jack@embed.me.uk>
Tested-by: Alexander Holler <holler@ahsoftware.de>
Tested-by: Jack Mitchell <jack@embed.me.uk>
Acked-by: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
index 52bf36d..debc5a7 100644 (file)
--- a/drivers/cpufreq/cpufreq-cpu0.c
+++ b/drivers/cpufreq/cpufreq-cpu0.c
@@ -71,12 +71,15 @@ static int cpu0_set_target(struct cpufreq_policy *policy,
        }
 
        if (cpu_reg) {
+               rcu_read_lock();
                opp = opp_find_freq_ceil(cpu_dev, &freq_Hz);
                if (IS_ERR(opp)) {
+                       rcu_read_unlock();
                        pr_err("failed to find OPP for %ld\n", freq_Hz);
                        return PTR_ERR(opp);
                }
                volt = opp_get_voltage(opp);
+               rcu_read_unlock();
                tol = volt * voltage_tolerance / 100;
                volt_old = regulator_get_voltage(cpu_reg);
        }
@@ -236,12 +239,14 @@ static int cpu0_cpufreq_driver_init(void)
                 */
                for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
                        ;
+               rcu_read_lock();
                opp = opp_find_freq_exact(cpu_dev,
                                freq_table[0].frequency * 1000, true);
                min_uV = opp_get_voltage(opp);
                opp = opp_find_freq_exact(cpu_dev,
                                freq_table[i-1].frequency * 1000, true);
                max_uV = opp_get_voltage(opp);
+               rcu_read_unlock();
                ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
                if (ret > 0)
                        transition_latency += ret * 1000;