[PATCH 3.14 25/78] cpufreq: remove race while accessing cur_policy

Greg Kroah-Hartman
2014-06-09T23:08:51Z

From: Bibek Basu <bbasu@nvidia.com>

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 : [<c05652b8>] lr : [<c05652b0>] 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
[<c05652b8>] (cpufreq_governor_dbs+0x400/0x634) from [<c055f700>] (__cpufreq_governor+0x98/0x1b4)
[<c055f700>] (__cpufreq_governor+0x98/0x1b4) from [<c0560770>] (__cpufreq_set_policy+0x250/0x320)
[<c0560770>] (__cpufreq_set_policy+0x250/0x320) from [<c0561dcc>] (cpufreq_update_policy+0xcc/0x168)
[<c0561dcc>] (cpufreq_update_policy+0xcc/0x168) from [<c0561ed0>] (cpu_freq_notify+0x68/0xdc)
[<c0561ed0>] (cpu_freq_notify+0x68/0xdc) from [<c008eff8>] (notifier_call_chain+0x4c/0x8c)
[<c008eff8>] (notifier_call_chain+0x4c/0x8c) from [<c008f3d4>] (__blocking_notifier_call_chain+0x50/0x68)
[<c008f3d4>] (__blocking_notifier_call_chain+0x50/0x68) from [<c008f40c>] (blocking_notifier_call_chain+0x20/0x28)
[<c008f40c>] (blocking_notifier_call_chain+0x20/0x28) from [<c00aac6c>] (pm_qos_update_bounded_target+0xd8/0x310)
[<c00aac6c>] (pm_qos_update_bounded_target+0xd8/0x310) from [<c00ab3b0>] (__pm_qos_update_request+0x64/0x70)
[<c00ab3b0>] (__pm_qos_update_request+0x64/0x70) from [<c004b4b8>] (tegra_pm_notify+0x114/0x134)
[<c004b4b8>] (tegra_pm_notify+0x114/0x134) from [<c008eff8>] (notifier_call_chain+0x4c/0x8c)
[<c008eff8>] (notifier_call_chain+0x4c/0x8c) from [<c008f3d4>] (__blocking_notifier_call_chain+0x50/0x68)
[<c008f3d4>] (__blocking_notifier_call_chain+0x50/0x68) from [<c008f40c>] (blocking_notifier_call_chain+0x20/0x28)
[<c008f40c>] (blocking_notifier_call_chain+0x20/0x28) from [<c00ac228>] (pm_notifier_call_chain+0x1c/0x34)
[<c00ac228>] (pm_notifier_call_chain+0x1c/0x34) from [<c00ad38c>] (enter_state+0xec/0x128)
[<c00ad38c>] (enter_state+0xec/0x128) from [<c00ad400>] (pm_suspend+0x38/0xa4)
[<c00ad400>] (pm_suspend+0x38/0xa4) from [<c00ac114>] (state_store+0x70/0xc0)
[<c00ac114>] (state_store+0x70/0xc0) from [<c027b1e8>] (kobj_attr_store+0x14/0x20)
[<c027b1e8>] (kobj_attr_store+0x14/0x20) from [<c019cd9c>] (sysfs_write_file+0x104/0x184)
[<c019cd9c>] (sysfs_write_file+0x104/0x184) from [<c0143038>] (vfs_write+0xd0/0x19c)
[<c0143038>] (vfs_write+0xd0/0x19c) from [<c0143414>] (SyS_write+0x4c/0x78)
[<c0143414>] (SyS_write+0x4c/0x78) from [<c000f080>] (ret_fast_syscall+0x0/0x30)
Code: e1a00006 eb084346 e59b0020 e5951024 (e5903028)
---[ end trace 0488523c8f6b0f9d ]---

Signed-off-by: Bibek Basu <bbasu@nvidia.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/cpufreq/cpufreq_governor.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -366,6 +366,11 @@ int cpufreq_governor_dbs(struct cpufreq_
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->min, CPUFREQ_RELATION_L);
dbs_check_cpu(dbs_data, cpu);
mutex_unlock(&cpu_cdbs->timer_mutex);
+ mutex_unlock(&dbs_data->mutex);
break;
}
return 0;