From 37473397b852f556d8b9428ccbfd51886037842d Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Thu, 13 Apr 2023 17:34:17 -0700 Subject: [PATCH] regulator: core: Make regulator_lock_two() logic easier to follow The regulator_lock_two() function could be made clearer in the case of lock contention by having a local variable for each of the held and contended locks. Let's do that. At the same time, let's use the swap() function instead of open coding it. This change is expected to be a no-op and simply improves code clarity. Suggested-by: Stephen Boyd Link: https://lore.kernel.org/r/CAE-0n53Eb1BeDPmjBycXUaQAF4ppiAM6UDWje_jiB9GAmR8MMw@mail.gmail.com Signed-off-by: Douglas Anderson Link: https://lore.kernel.org/r/20230413173359.1.I1ae92b25689bd6579952e6d458b79f5f8054a0c9@changeid Signed-off-by: Mark Brown --- drivers/regulator/core.c | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 08726bc0da9d..dc741ac156c3 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -219,7 +219,7 @@ static void regulator_lock_two(struct regulator_dev *rdev1, struct regulator_dev *rdev2, struct ww_acquire_ctx *ww_ctx) { - struct regulator_dev *tmp; + struct regulator_dev *held, *contended; int ret; ww_acquire_init(ww_ctx, ®ulator_ww_class); @@ -233,25 +233,18 @@ static void regulator_lock_two(struct regulator_dev *rdev1, goto exit; } + held = rdev1; + contended = rdev2; 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); + regulator_unlock(held); - ww_mutex_lock_slow(&rdev2->mutex, ww_ctx); - rdev2->ref_cnt++; - rdev2->mutex_owner = current; - ret = regulator_lock_nested(rdev1, ww_ctx); + ww_mutex_lock_slow(&contended->mutex, ww_ctx); + contended->ref_cnt++; + contended->mutex_owner = current; + swap(held, contended); + ret = regulator_lock_nested(contended, ww_ctx); - if (ret == -EDEADLOCK) { - /* More contention; swap which needs to be slow */ - tmp = rdev1; - rdev1 = rdev2; - rdev2 = tmp; - } else { + if (ret != -EDEADLOCK) { WARN_ON(ret); break; }