diff options
| -rw-r--r-- | drivers/regulator/core.c | 91 |
1 files changed, 83 insertions, 8 deletions
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 9a13240f3084..08726bc0da9d 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -207,6 +207,78 @@ static void regulator_unlock(struct regulator_dev *rdev) mutex_unlock(®ulator_nesting_mutex); } +/** + * regulator_lock_two - lock two regulators + * @rdev1: first regulator + * @rdev2: second regulator + * @ww_ctx: w/w mutex acquire context + * + * Locks both rdevs using the regulator_ww_class. + */ +static void regulator_lock_two(struct regulator_dev *rdev1, + struct regulator_dev *rdev2, + struct ww_acquire_ctx *ww_ctx) +{ + struct regulator_dev *tmp; + int ret; + + ww_acquire_init(ww_ctx, ®ulator_ww_class); + + /* Try to just grab both of them */ + ret = regulator_lock_nested(rdev1, ww_ctx); + WARN_ON(ret); + ret = regulator_lock_nested(rdev2, ww_ctx); + if (ret != -EDEADLOCK) { + WARN_ON(ret); + goto exit; + } + + while (true) { + /* + * Start of loop: rdev1 was locked and rdev2 was contended. + * Need to unlock rdev1, slowly lock rdev2, then try rdev1 + * again. + */ + regulator_unlock(rdev1); + + ww_mutex_lock_slow(&rdev2->mutex, ww_ctx); + rdev2->ref_cnt++; + rdev2->mutex_owner = current; + ret = regulator_lock_nested(rdev1, ww_ctx); + + if (ret == -EDEADLOCK) { + /* More contention; swap which needs to be slow */ + tmp = rdev1; + rdev1 = rdev2; + rdev2 = tmp; + } else { + WARN_ON(ret); + break; + } + } + +exit: + ww_acquire_done(ww_ctx); +} + +/** + * regulator_unlock_two - unlock two regulators + * @rdev1: first regulator + * @rdev2: second regulator + * @ww_ctx: w/w mutex acquire context + * + * The inverse of regulator_lock_two(). + */ + +static void regulator_unlock_two(struct regulator_dev *rdev1, + struct regulator_dev *rdev2, + struct ww_acquire_ctx *ww_ctx) +{ + regulator_unlock(rdev2); + regulator_unlock(rdev1); + ww_acquire_fini(ww_ctx); +} + static bool regulator_supply_is_couple(struct regulator_dev *rdev) { struct regulator_dev *c_rdev; @@ -1627,8 +1699,8 @@ static int set_machine_constraints(struct regulator_dev *rdev) /** * set_supply - set regulator supply regulator - * @rdev: regulator name - * @supply_rdev: supply regulator name + * @rdev: regulator (locked) + * @supply_rdev: supply regulator (locked)) * * Called by platform initialisation code to set the supply regulator for this * regulator. This ensures that a regulators supply will also be enabled by the @@ -1800,6 +1872,8 @@ static struct regulator *create_regulator(struct regulator_dev *rdev, struct regulator *regulator; int err = 0; + lockdep_assert_held_once(&rdev->mutex.base); + if (dev) { char buf[REG_STR_SIZE]; int size; @@ -1827,9 +1901,7 @@ static struct regulator *create_regulator(struct regulator_dev *rdev, regulator->rdev = rdev; regulator->supply_name = supply_name; - regulator_lock(rdev); list_add(®ulator->list, &rdev->consumer_list); - regulator_unlock(rdev); if (dev) { regulator->dev = dev; @@ -1995,6 +2067,7 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) { struct regulator_dev *r; struct device *dev = rdev->dev.parent; + struct ww_acquire_ctx ww_ctx; int ret = 0; /* No supply to resolve? */ @@ -2061,23 +2134,23 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) * between rdev->supply null check and setting rdev->supply in * set_supply() from concurrent tasks. */ - regulator_lock(rdev); + regulator_lock_two(rdev, r, &ww_ctx); /* Supply just resolved by a concurrent task? */ if (rdev->supply) { - regulator_unlock(rdev); + regulator_unlock_two(rdev, r, &ww_ctx); put_device(&r->dev); goto out; } ret = set_supply(rdev, r); if (ret < 0) { - regulator_unlock(rdev); + regulator_unlock_two(rdev, r, &ww_ctx); put_device(&r->dev); goto out; } - regulator_unlock(rdev); + regulator_unlock_two(rdev, r, &ww_ctx); /* * In set_machine_constraints() we may have turned this regulator on @@ -2190,7 +2263,9 @@ struct regulator *_regulator_get(struct device *dev, const char *id, return regulator; } + regulator_lock(rdev); regulator = create_regulator(rdev, dev, id); + regulator_unlock(rdev); if (regulator == NULL) { regulator = ERR_PTR(-ENOMEM); module_put(rdev->owner); |