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: Alexander Holler <holler@xxxxxxxxxxxxx> Tested-by: Alexander Holler <holler@xxxxxxxxxxxxx> Acked-by: Alexander Holler <holler@xxxxxxxxxxxxx> Signed-off-by: Nishanth Menon <nm@xxxxxx> --- drivers/cpufreq/omap-cpufreq.c | 3 +++ 1 file changed, 3 insertions(+) Fixes warning as follows: http://dpaste.de/5j4qX/ [ 5.175323] =============================== [ 5.179901] [ INFO: suspicious RCU usage. ] [ 5.184295] 3.7.1-beagleboard-00018-g65ab3da-dirty #180 Not tainted [ 5.190979] ------------------------------- [ 5.195465] drivers/base/power/opp.c:155 suspicious rcu_dereference_check() usage! [ 5.203460] [ 5.203460] other info that might help us debug this: [ 5.203460] [ 5.211914] [ 5.211914] rcu_scheduler_active = 1, debug_locks = 0 [ 5.219055] 3 locks held by swapper/1: [ 5.222991] #0: (subsys mutex#5){+.+.+.}, at: [<c026217c>] subsys_interface_register+0x34/0xbc [ 5.232360] #1: (&per_cpu(cpu_policy_rwsem, cpu)){+.+.+.}, at: [<c02d9374>] lock_policy_rwsem_write+0x24/0x48 [ 5.243072] #2: (&this_dbs_info->timer_mutex){+.+...}, at: [<c02db234>] cpufreq_governor_dbs+0x2e8/0x380 [ 5.253295] [ 5.253295] stack backtrace: [ 5.257965] [<c0013198>] (unwind_backtrace+0x0/0xe0) from [<c026bd08>] (opp_get_voltage+0x5c/0xc0) [ 5.267395] [<c026bd08>] (opp_get_voltage+0x5c/0xc0) from [<c02db928>] (omap_target+0x180/0x364) [ 5.276672] [<c02db928>] (omap_target+0x180/0x364) from [<c02d8bbc>] (__cpufreq_driver_target+0x38/0x54) [ 5.303039] [<c02d8bbc>] (__cpufreq_driver_target+0x38/0x54) from [<c02db260>] (cpufreq_governor_dbs+0x314/0x380) [ 5.313903] [<c02db260>] (cpufreq_governor_dbs+0x314/0x380) from [<c02d948c>] (__cpufreq_governor+0x70/0xb4) [ 5.324310] [<c02d948c>] (__cpufreq_governor+0x70/0xb4) from [<c02d96fc>] (__cpufreq_set_policy+0x150/0x168) [ 5.334686] [<c02d96fc>] (__cpufreq_set_policy+0x150/0x168) from [<c02d9ae0>] (cpufreq_add_dev_interface+0x17c/0x1f0) [ 5.345886] [<c02d9ae0>] (cpufreq_add_dev_interface+0x17c/0x1f0) from [<c02d9c80>] (cpufreq_add_dev+0x12c/0x1d8) [ 5.356628] [<c02d9c80>] (cpufreq_add_dev+0x12c/0x1d8) from [<c02621c4>] (subsys_interface_register+0x7c/0xbc) [ 5.367187] [<c02621c4>] (subsys_interface_register+0x7c/0xbc) from [<c02d91bc>] (cpufreq_register_driver+0x9c/0x128) [ 5.378387] [<c02d91bc>] (cpufreq_register_driver+0x9c/0x128) from [<c00086a0>] (do_one_initcall+0x90/0x164) [ 5.395812] [<c00086a0>] (do_one_initcall+0x90/0x164) from [<c03d5740>] (kernel_init+0xe4/0x298) [ 5.408569] [<c03d5740>] (kernel_init+0xe4/0x298) from [<c000de30>] (ret_from_fork+0x14/0x24) diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c index 1f3417a..97102b0 100644 --- a/drivers/cpufreq/omap-cpufreq.c +++ b/drivers/cpufreq/omap-cpufreq.c @@ -110,13 +110,16 @@ static int omap_target(struct cpufreq_policy *policy, freq = ret; if (mpu_reg) { + rcu_read_lock(); opp = opp_find_freq_ceil(mpu_dev, &freq); if (IS_ERR(opp)) { + rcu_read_unlock(); dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n", __func__, freqs.new); return -EINVAL; } volt = opp_get_voltage(opp); + rcu_read_unlock(); tol = volt * OPP_TOLERANCE / 100; volt_old = regulator_get_voltage(mpu_reg); } -- 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
