From d92d95b6bf2722ffa0fefa7651c51bf336743dd7 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Mon, 2 Jul 2012 19:21:06 -0700 Subject: [PATCH] regulator: Fix recursive mutex lockdep warning A recursive lockdep warning occurs if you call regulator_set_optimum_mode() on a regulator with a supply because there is no nesting annotation for the rdev->mutex. To avoid this warning, get the supply's load before locking the regulator's mutex to avoid grabbing the same class of lock twice. ============================================= [ INFO: possible recursive locking detected ] 3.4.0 #3257 Tainted: G W --------------------------------------------- swapper/0/1 is trying to acquire lock: (&rdev->mutex){+.+.+.}, at: [] regulator_get_voltage+0x18/0x38 but task is already holding lock: (&rdev->mutex){+.+.+.}, at: [] regulator_set_optimum_mode+0x24/0x224 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rdev->mutex); lock(&rdev->mutex); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by swapper/0/1: #0: (&__lockdep_no_validate__){......}, at: [] __driver_attach+0x40/0x8c #1: (&__lockdep_no_validate__){......}, at: [] __driver_attach+0x50/0x8c #2: (&rdev->mutex){+.+.+.}, at: [] regulator_set_optimum_mode+0x24/0x224 stack backtrace: [] (unwind_backtrace+0x0/0x12c) from [] (validate_chain+0x760/0x1080) [] (validate_chain+0x760/0x1080) from [] (__lock_acquire+0x950/0xa10) [] (__lock_acquire+0x950/0xa10) from [] (lock_acquire+0x18c/0x1e8) [] (lock_acquire+0x18c/0x1e8) from [] (mutex_lock_nested+0x68/0x3c4) [] (mutex_lock_nested+0x68/0x3c4) from [] (regulator_get_voltage+0x18/0x38) [] (regulator_get_voltage+0x18/0x38) from [] (regulator_set_optimum_mode+0xa4/0x224) ... Signed-off-by: Stephen Boyd Signed-off-by: Mark Brown --- drivers/regulator/core.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 09a737c868b5..8b4b3829d9e7 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -2519,9 +2519,12 @@ int regulator_set_optimum_mode(struct regulator *regulator, int uA_load) { struct regulator_dev *rdev = regulator->rdev; struct regulator *consumer; - int ret, output_uV, input_uV, total_uA_load = 0; + int ret, output_uV, input_uV = 0, total_uA_load = 0; unsigned int mode; + if (rdev->supply) + input_uV = regulator_get_voltage(rdev->supply); + mutex_lock(&rdev->mutex); /* @@ -2554,10 +2557,7 @@ int regulator_set_optimum_mode(struct regulator *regulator, int uA_load) goto out; } - /* get input voltage */ - input_uV = 0; - if (rdev->supply) - input_uV = regulator_get_voltage(rdev->supply); + /* No supply? Use constraint voltage */ if (input_uV <= 0) input_uV = rdev->constraints->input_uV; if (input_uV <= 0) { -- 2.20.1