diff options
Diffstat (limited to 'drivers/regulator')
-rw-r--r-- | drivers/regulator/core.c | 39 |
1 files changed, 28 insertions, 11 deletions
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 8a6ca06d9c16..fa8f5fc04d8f 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -1567,23 +1567,34 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) { struct regulator_dev *r; struct device *dev = rdev->dev.parent; - int ret; + int ret = 0; /* No supply to resovle? */ if (!rdev->supply_name) return 0; - /* Supply already resolved? */ + /* Supply already resolved? (fast-path without locking contention) */ if (rdev->supply) return 0; + /* + * Recheck rdev->supply with rdev->mutex lock held to avoid a race + * between rdev->supply null check and setting rdev->supply in + * set_supply() from concurrent tasks. + */ + regulator_lock(rdev); + + /* Supply just resolved by a concurrent task? */ + if (rdev->supply) + goto out; + r = regulator_dev_lookup(dev, rdev->supply_name); if (IS_ERR(r)) { ret = PTR_ERR(r); /* Did the lookup explicitly defer for us? */ if (ret == -EPROBE_DEFER) - return ret; + goto out; if (have_full_constraints()) { r = dummy_regulator_rdev; @@ -1591,15 +1602,18 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) } else { dev_err(dev, "Failed to resolve %s-supply for %s\n", rdev->supply_name, rdev->desc->name); - return -EPROBE_DEFER; + ret = -EPROBE_DEFER; + goto out; } } if (r == rdev) { dev_err(dev, "Supply for %s (%s) resolved to itself\n", rdev->desc->name, rdev->supply_name); - if (!have_full_constraints()) - return -EINVAL; + if (!have_full_constraints()) { + ret = -EINVAL; + goto out; + } r = dummy_regulator_rdev; get_device(&r->dev); } @@ -1613,7 +1627,8 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) if (r->dev.parent && r->dev.parent != rdev->dev.parent) { if (!device_is_bound(r->dev.parent)) { put_device(&r->dev); - return -EPROBE_DEFER; + ret = -EPROBE_DEFER; + goto out; } } @@ -1621,13 +1636,13 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) ret = regulator_resolve_supply(r); if (ret < 0) { put_device(&r->dev); - return ret; + goto out; } ret = set_supply(rdev, r); if (ret < 0) { put_device(&r->dev); - return ret; + goto out; } /* Cascade always-on state to supply */ @@ -1636,11 +1651,13 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) if (ret < 0) { _regulator_put(rdev->supply); rdev->supply = NULL; - return ret; + goto out; } } - return 0; +out: + regulator_unlock(rdev); + return ret; } /* Internal regulator request function */ |