Hi Michael,
On Fri, 07 Sep 2012 15:00:53 +0200, Michael Lawnick wrote:
> 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 <[email protected]>
> > Cc: Jean Delvare <[email protected]
> > ---
> > 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 :-(
Yes, I noticed the problem too. Actually I have a reply for you in my
draft folder, saying exactly that.
> Please ignore, other solution is under construction.
I do have one too, based on the depth level of each adapter:
--- linux-3.6-rc4.orig/drivers/i2c/i2c-core.c 2012-09-06 17:24:17.449441802
+0200
+++ linux-3.6-rc4/drivers/i2c/i2c-core.c 2012-09-07 10:44:11.339368610
+0200
@@ -636,6 +636,16 @@ static void i2c_adapter_dev_release(stru
complete(&adap->dev_released);
}
+static unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
+{
+ unsigned int depth = 0;
+
+ while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
+ depth++;
+
+ return depth;
+}
+
/*
* Let users instantiate I2C devices through sysfs. This can be used when
* platform initialization code doesn't contain the proper data for
@@ -726,7 +736,8 @@ 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_depth(adap));
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
if (client->addr == addr) {
@@ -869,7 +880,8 @@ static int i2c_register_adapter(struct i
if (res)
goto out_list;
- dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
+ dev_dbg(&adap->dev, "adapter [%s] registered, depth %u\n", adap->name,
+ i2c_adapter_depth(adap));
#ifdef CONFIG_I2C_COMPAT
res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
@@ -1073,7 +1085,8 @@ 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_depth(adap));
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
I was about to test it but was side-tracked by a different issue.
--
Jean Delvare
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