Re: [PATCH] i2c-core: fix for dep-lock validator

[Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>]

Am 05.09.2012 14:04, schrieb Michael Lawnick:
> 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-Mmb7MZpHnFY@public.gmane.org>
> Cc: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org
> ---
> 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,

This will get problems with maximum log level :-(
Please ignore, other solution is under construction.

-- 
KR
Michael