From: Mark Brown <broonie@xxxxxxxxxx> [ Upstream commit 14a71d509ac809dcf56d7e3ca376b15d17bd0ddd ] With commit eaa7995c529b54 (regulator: core: avoid regulator_resolve_supply() race condition) we started holding the rdev lock while resolving supplies, an operation that requires holding the regulator_list_mutex. This results in lockdep warnings since in other places we take the list mutex then the mutex on an individual rdev. Since the goal is to make sure that we don't call set_supply() twice rather than a concern about the cost of resolution pull the rdev lock and check for duplicate resolution down to immediately before we do the set_supply() and drop it again once the allocation is done. Fixes: eaa7995c529b54 (regulator: core: avoid regulator_resolve_supply() race condition) Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210122132042.10306-1-broonie@xxxxxxxxxx Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/regulator/core.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 2c31f04ff950f..35098dbd32a3c 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -1823,17 +1823,6 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) 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); @@ -1885,12 +1874,29 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) goto out; } + /* + * 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) { + regulator_unlock(rdev); + put_device(&r->dev); + goto out; + } + ret = set_supply(rdev, r); if (ret < 0) { + regulator_unlock(rdev); put_device(&r->dev); goto out; } + regulator_unlock(rdev); + /* * In set_machine_constraints() we may have turned this regulator on * but we couldn't propagate to the supply if it hadn't been resolved @@ -1906,7 +1912,6 @@ static int regulator_resolve_supply(struct regulator_dev *rdev) } out: - regulator_unlock(rdev); return ret; } -- 2.27.0
