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@xxxxxxxxxxx> Tested-by: Alexander Holler <holler@xxxxxxxxxxxxx> Tested-by: Jack Mitchell <jack@xxxxxxxxxxx> Acked-by: Alexander Holler <holler@xxxxxxxxxxxxx> Signed-off-by: Nishanth Menon <nm@xxxxxx> --- drivers/cpufreq/cpufreq-cpu0.c | 5 +++++ 1 file changed, 5 insertions(+) Fixes warning as shown in: http://pastebin.com/6Y0bpCFi Something similar to this was attempted to be addressed by: https://patchwork.kernel.org/patch/879022/ [ 2.321123] =============================== [ 2.325591] [ INFO: suspicious RCU usage. ] [ 2.330063] 3.8.0-rc4-00291-gbb85e3f-dirty #2 Not tainted [ 2.335805] ------------------------------- [ 2.340270] drivers/base/power/opp.c:157 suspicious rcu_dereference_check() usage! [ 2.348285] other info that might help us debug this: [ 2.356769] rcu_scheduler_active = 1, debug_locks = 1 [ 2.363727] no locks held by swapper/0/1. [ 2.368006] stack backtrace: [ 2.372707] [<c0013678>] (unwind_backtrace+0x0/0xe0) from [<c03475bc>] (opp_get_voltage+0x78/0xc8) [ 2.382219] [<c03475bc>] (opp_get_voltage+0x78/0xc8) from [<c04046e4>] (cpu0_cpufreq_driver_init+0x154/0x208) [ 2.392727] [<c04046e4>] (cpu0_cpufreq_driver_init+0x154/0x208) from [<c0008878>] (do_one_initcall+0x90/0x164) [ 2.403323] [<c0008878>] (do_one_initcall+0x90/0x164) from [<c0547698>] (kernel_init+0xf8/0x290) [ 2.412646] [<c0547698>] (kernel_init+0xf8/0x290) from [<c000d9b0>] (ret_from_fork+0x14/0x24) diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c index 52bf36d..debc5a7 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; -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
