From a83b02fc812285bb7fd705cfea421d146ca31c0a Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Fri, 22 Jan 2021 13:20:42 +0000 Subject: [PATCH] UPSTREAM: regulator: Fix lockdep warning resolving supplies 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 Tested-by: Marek Szyprowski Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20210122132042.10306-1-broonie@kernel.org Signed-off-by: Mark Brown (cherry picked from commit 14a71d509ac809dcf56d7e3ca376b15d17bd0ddd) Bug: 177002490 Change-Id: I4b39edb5bf765d6d7ded275d70dfcf0839842f64 Signed-off-by: David Collins --- drivers/regulator/core.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 2c31f04ff950..35098dbd32a3 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; } - ret = set_supply(rdev, r); - if (ret < 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) { + 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; }