Merge pull request #407 from aeickho/backport-fix-drivers_w1_w1.c

w1 - call request_module with w1 master mutex unlocked

Author: popcornmix

drivers/w1/w1.c

@@ -680,7 +680,10 @@ static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
 	atomic_set(&sl->refcnt, 0);
 	init_completion(&sl->released);
 
+	/* slave modules need to be loaded in a context with unlocked mutex */
+	mutex_unlock(&dev->mutex);
 	request_module("w1-family-0x%0x", rn->family);
+	mutex_lock(&dev->mutex);
 
 	spin_lock(&w1_flock);
 	f = w1_family_registered(rn->family);