From 89571e8509f62d950715faca2251eb2273b530a0 Mon Sep 17 00:00:00 2001 From: Bibek Basu Date: Mon, 19 May 2014 10:24:01 +0530 Subject: [PATCH] cpufreq: remove race while accessing cur_policy commit c5450db85b828d0c46ac8fc570fb8a51bf07ac40 upstream. While accessing cur_policy during executing events CPUFREQ_GOV_START, CPUFREQ_GOV_STOP, CPUFREQ_GOV_LIMITS, same mutex lock is not taken, dbs_data->mutex, which leads to race and data corruption while running continious suspend resume test. This is seen with ondemand governor with suspend resume test using rtcwake. Unable to handle kernel NULL pointer dereference at virtual address 00000028 pgd = ed610000 [00000028] *pgd=adf11831, *pte=00000000, *ppte=00000000 Internal error: Oops: 17 [#1] PREEMPT SMP ARM Modules linked in: nvhost_vi CPU: 1 PID: 3243 Comm: rtcwake Not tainted 3.10.24-gf5cf9e5 #1 task: ee708040 ti: ed61c000 task.ti: ed61c000 PC is at cpufreq_governor_dbs+0x400/0x634 LR is at cpufreq_governor_dbs+0x3f8/0x634 pc : [] lr : [] psr: 600f0013 sp : ed61dcb0 ip : 000493e0 fp : c1cc14f0 r10: 00000000 r9 : 00000000 r8 : 00000000 r7 : eb725280 r6 : c1cc1560 r5 : eb575200 r4 : ebad7740 r3 : ee708040 r2 : ed61dca8 r1 : 001ebd24 r0 : 00000000 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user Control: 10c5387d Table: ad61006a DAC: 00000015 [] (cpufreq_governor_dbs+0x400/0x634) from [] (__cpufreq_governor+0x98/0x1b4) [] (__cpufreq_governor+0x98/0x1b4) from [] (__cpufreq_set_policy+0x250/0x320) [] (__cpufreq_set_policy+0x250/0x320) from [] (cpufreq_update_policy+0xcc/0x168) [] (cpufreq_update_policy+0xcc/0x168) from [] (cpu_freq_notify+0x68/0xdc) [] (cpu_freq_notify+0x68/0xdc) from [] (notifier_call_chain+0x4c/0x8c) [] (notifier_call_chain+0x4c/0x8c) from [] (__blocking_notifier_call_chain+0x50/0x68) [] (__blocking_notifier_call_chain+0x50/0x68) from [] (blocking_notifier_call_chain+0x20/0x28) [] (blocking_notifier_call_chain+0x20/0x28) from [] (pm_qos_update_bounded_target+0xd8/0x310) [] (pm_qos_update_bounded_target+0xd8/0x310) from [] (__pm_qos_update_request+0x64/0x70) [] (__pm_qos_update_request+0x64/0x70) from [] (tegra_pm_notify+0x114/0x134) [] (tegra_pm_notify+0x114/0x134) from [] (notifier_call_chain+0x4c/0x8c) [] (notifier_call_chain+0x4c/0x8c) from [] (__blocking_notifier_call_chain+0x50/0x68) [] (__blocking_notifier_call_chain+0x50/0x68) from [] (blocking_notifier_call_chain+0x20/0x28) [] (blocking_notifier_call_chain+0x20/0x28) from [] (pm_notifier_call_chain+0x1c/0x34) [] (pm_notifier_call_chain+0x1c/0x34) from [] (enter_state+0xec/0x128) [] (enter_state+0xec/0x128) from [] (pm_suspend+0x38/0xa4) [] (pm_suspend+0x38/0xa4) from [] (state_store+0x70/0xc0) [] (state_store+0x70/0xc0) from [] (kobj_attr_store+0x14/0x20) [] (kobj_attr_store+0x14/0x20) from [] (sysfs_write_file+0x104/0x184) [] (sysfs_write_file+0x104/0x184) from [] (vfs_write+0xd0/0x19c) [] (vfs_write+0xd0/0x19c) from [] (SyS_write+0x4c/0x78) [] (SyS_write+0x4c/0x78) from [] (ret_fast_syscall+0x0/0x30) Code: e1a00006 eb084346 e59b0020 e5951024 (e5903028) ---[ end trace 0488523c8f6b0f9d ]--- Signed-off-by: Bibek Basu Acked-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman --- drivers/cpufreq/cpufreq_governor.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index ba43991..e1c6433 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -366,6 +366,11 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, break; case CPUFREQ_GOV_LIMITS: + mutex_lock(&dbs_data->mutex); + if (!cpu_cdbs->cur_policy) { + mutex_unlock(&dbs_data->mutex); + break; + } mutex_lock(&cpu_cdbs->timer_mutex); if (policy->max < cpu_cdbs->cur_policy->cur) __cpufreq_driver_target(cpu_cdbs->cur_policy, @@ -375,6 +380,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, policy->min, CPUFREQ_RELATION_L); dbs_check_cpu(dbs_data, cpu); mutex_unlock(&cpu_cdbs->timer_mutex); + mutex_unlock(&dbs_data->mutex); break; } return 0; -- 2.7.4