If kernel is compiled with CONFIG_PROVE_LOCKING the
validator raises an error when a multiplexer is removed
via sysfs and sub-clients are connected to it. This is a
false positive.
Documentation/lockdep-design.txt recommends to handle this
via calls to mutex_lock_nested()
Signed-off-by: Michael Lawnick <ml.lawnick@xxxxxx>
Cc: Jean Delvare <khali@xxxxxxxxxxxx
---
Documentation originally recommends to use an enum.
This is not applicable for a tree with unlimited depth.
This is why I use the adapter id which is expected
to be unique and monotonic increasing with the depth of
the tree.
--- linux/drivers/i2c/i2c-core.c.dist 2012-09-05 09:46:50.000000000 +0200
+++ linux/drivers/i2c/i2c-core.c 2012-09-05 09:56:58.000000000 +0200
@@ -628,7 +628,7 @@ i2c_sysfs_delete_device(struct device *d
/* Make sure the device was added through sysfs */
res = -ENOENT;
- mutex_lock(&adap->userspace_clients_lock);
+ mutex_lock_nested(&adap->userspace_clients_lock, i2c_adapter_id(adap));
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
if (client->addr == addr) {
@@ -936,7 +936,7 @@ int i2c_del_adapter(struct i2c_adapter *
return res;
/* Remove devices instantiated from sysfs */
- mutex_lock(&adap->userspace_clients_lock);
+ mutex_lock_nested(&adap->userspace_clients_lock, i2c_adapter_id(adap));
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
--
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