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>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
index 52bf36d599f5..debc5a7c8db6 100644
--- 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;