When adapters are chained in a sparse manner (with intermediate MFD devices,
for instance) the code currently fails to use the correct subclass for
the adapter's bus_lock which leads to false-positive lockdep warnings.
Fix this by walking the entire pedigree of the device and count all
adapters along the way instead of just checking the immediate parent.
Signed-off-by: Daniel Mack <daniel@xxxxxxxxxx>
---
This hit me when during the development of a driver stack that isn't
submitted mainline yet. This patch could however be discussed
independently I think.
drivers/i2c/i2c-core-base.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 60746652fd52..4692a1e5ea0a 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1189,9 +1189,11 @@ static void i2c_adapter_dev_release(struct device *dev)
unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
{
unsigned int depth = 0;
+ struct device *parent;
- while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
- depth++;
+ for (parent = adapter->dev.parent; parent; parent = parent->parent)
+ if (parent->type == &i2c_adapter_type)
+ depth++;
WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
"adapter depth exceeds lockdep subclass limit\n");
--
2.41.0
