i2c: Add support for nested i2c bus locking

This patch adds the 'level' field into the i2c_adapter structure, which is
used to represent the 'logical' level of nesting for the purposes of
lockdep. This field is then used in the i2c_transfer() function, to
acquire the per-adapter bus_lock with correct nesting level.

Signed-off-by: Jiri Kosina <jikos@jikos.cz>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 7ca81f4..79eaa12 100644 (file)
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -603,7 +603,7 @@ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num)
                }
 #endif
 
-               mutex_lock(&adap->bus_lock);
+               mutex_lock_nested(&adap->bus_lock, adap->level);
                ret = adap->algo->master_xfer(adap,msgs,num);
                mutex_unlock(&adap->bus_lock);
 

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 9b5d047..08df416 100644 (file)
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -216,6 +216,7 @@ struct i2c_adapter {
        int (*client_unregister)(struct i2c_client *);
 
        /* data fields that are valid for all devices   */
+       u8 level;                       /* nesting level for lockdep */
        struct mutex bus_lock;
        struct mutex clist_lock;