This is a note to let you know that I've just added the patch titled
regulator: core: fix deadlock on regulator enable
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
regulator-core-fix-deadlock-on-regulator-enable.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cb3543cff90a4448ed560ac86c98033ad5fecda9 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan+linaro@xxxxxxxxxx>
Date: Thu, 15 Dec 2022 11:46:46 +0100
Subject: regulator: core: fix deadlock on regulator enable
From: Johan Hovold <johan+linaro@xxxxxxxxxx>
commit cb3543cff90a4448ed560ac86c98033ad5fecda9 upstream.
When updating the operating mode as part of regulator enable, the caller
has already locked the regulator tree and drms_uA_update() must not try
to do the same in order not to trigger a deadlock.
The lock inversion is reported by lockdep as:
======================================================
WARNING: possible circular locking dependency detected
6.1.0-next-20221215 #142 Not tainted
------------------------------------------------------
udevd/154 is trying to acquire lock:
ffffc11f123d7e50 (regulator_list_mutex){+.+.}-{3:3}, at: regulator_lock_dependent+0x54/0x280
but task is already holding lock:
ffff80000e4c36e8 (regulator_ww_class_acquire){+.+.}-{0:0}, at: regulator_enable+0x34/0x80
which lock already depends on the new lock.
...
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(regulator_ww_class_acquire);
lock(regulator_list_mutex);
lock(regulator_ww_class_acquire);
lock(regulator_list_mutex);
*** DEADLOCK ***
just before probe of a Qualcomm UFS controller (occasionally) deadlocks
when enabling one of its regulators.
Fixes: 9243a195be7a ("regulator: core: Change voltage setting path")
Fixes: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking")
Cc: stable@xxxxxxxxxxxxxxx # 5.0
Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20221215104646.19818-1-johan+linaro@xxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/regulator/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -956,7 +956,7 @@ static int drms_uA_update(struct regulat
/* get input voltage */
input_uV = 0;
if (rdev->supply)
- input_uV = regulator_get_voltage(rdev->supply);
+ input_uV = regulator_get_voltage_rdev(rdev->supply->rdev);
if (input_uV <= 0)
input_uV = rdev->constraints->input_uV;
if (input_uV <= 0) {
Patches currently in stable-queue which might be from johan+linaro@xxxxxxxxxx are
queue-5.4/regulator-core-fix-deadlock-on-regulator-enable.patch
