Sometimes I get a NULL pointer dereference at boot time in kobject_get()
with the following call stack:
anatop_regulator_probe()
devm_regulator_register()
regulator_register()
regulator_resolve_supply()
kobject_get()
By placing some extra BUG_ON() statements I could verify that this is
raised because probing of the 'dummy' regulator driver is not completed
('dummy_regulator_rdev' is still NULL).
In the JTAG debugger I can see that dummy_regulator_probe() and
anatop_regulator_probe() can be run by different kernel threads
(kworker/u4:*). I haven't further investigated whether this can be
changed or if there are other possibilities to force synchronization
between these two probe routines. On the other hand I don't expect much
boot time penalty by probing the 'dummy' regulator synchronously.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 259b93b21a9f ("regulator: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in 4.14")
Signed-off-by: Christian Eggers <ceggers@xxxxxxx>
---
drivers/regulator/dummy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/regulator/dummy.c b/drivers/regulator/dummy.c
index 5b9b9e4e762d..9f59889129ab 100644
--- a/drivers/regulator/dummy.c
+++ b/drivers/regulator/dummy.c
@@ -60,7 +60,7 @@ static struct platform_driver dummy_regulator_driver = {
.probe = dummy_regulator_probe,
.driver = {
.name = "reg-dummy",
- .probe_type = PROBE_PREFER_ASYNCHRONOUS,
+ .probe_type = PROBE_FORCE_SYNCHRONOUS,
},
};
--
2.43.0
