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| author | Jean Delvare <khali@linux-fr.org> | 2012-09-10 10:14:02 +0200 |
|---|---|---|
| committer | Jean Delvare <khali@endymion.delvare> | 2012-09-10 10:14:02 +0200 |
| commit | 390946b17260797635cd9e65496b5a17b2db0a5d (patch) | |
| tree | 42c4f0a172149d7e6752ddf55284cb1fcb386eec /drivers/i2c | |
| parent | i2c-designware: Fix build error if CONFIG_I2C_DESIGNWARE_PLATFORM=y && CONFIG... (diff) | |
| download | linux-390946b17260797635cd9e65496b5a17b2db0a5d.tar.xz linux-390946b17260797635cd9e65496b5a17b2db0a5d.zip | |
i2c-core: Fix for lockdep validator
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 <khali@linux-fr.org>
Cc: Michael Lawnick <ml.lawnick@gmx.de>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/i2c-core.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 2efa56c5ff2c..2091ae8f539a 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -637,6 +637,22 @@ static void i2c_adapter_dev_release(struct device *dev) } /* + * 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 *dev, struct device_attribute *attr, /* 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 *adap) 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, |