Am 08.09.2012 09:38, schrieb Jean Delvare: > 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(). > > Based on an earlier fix from Michael Lawnick. > > Note that the extra code resolves to nothing unless > CONFIG_DEBUG_LOCK_ALLOC=y. > > Signed-off-by: Jean Delvare <[email protected]> > Cc: Michael Lawnick <[email protected]>
Tested-by: Michael Lawnick <[email protected]> Acked-by: Michael Lawnick <[email protected]> > --- > Changes since v2: > * Inline function i2c_adapter_depth to avoid a compiler warning. > * Document the reason why it it implemented that way. > > drivers/i2c/i2c-core.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > --- linux-3.6-rc4.orig/drivers/i2c/i2c-core.c 2012-09-07 17:53:31.000000000 > +0200 > +++ linux-3.6-rc4/drivers/i2c/i2c-core.c 2012-09-08 09:36:13.538537033 > +0200 > @@ -637,6 +637,22 @@ static void i2c_adapter_dev_release(stru > } > > /* > + * This function is only needed for mutex_lock_nested, so it is never > + * called unless locking correctness checking is enabled. Thus we > + * make it inline to avoid a compiler warning. That's what gcc ends up > + * doing anyway. > + */ > +static inline 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 > * whatever reason. Also useful for drivers that do device detection and > @@ -726,7 +742,8 @@ 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) { > @@ -1073,7 +1090,8 @@ 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, > > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
