W1: fix deadlocks and remove w1_control_thread

w1_control_thread was removed which would wake up every second and process
newly registered family codes and complete some final cleanup for a
removed master.  Those routines were moved to the threads that were
previously requesting those operations.  A new function
w1_reconnect_slaves takes care of reconnecting existing slave devices when
a new family code is registered or removed.  The removal case was missing
and would cause a deadlock waiting for the family code reference count to
decrease, which will now happen.  A problem with registering a family code
was fixed.  A slave device would be unattached if it wasn't yet claimed,
then attached at the end of the list, two unclaimed slaves would cause an
infinite loop.

The struct w1_bus_master.search now takes a pointer to the struct
w1_master device to avoid searching for it, which would have caused a
lock ordering deadlock with the removal of w1_control_thread.

Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/w1/w1_family.c b/drivers/w1/w1_family.c
index a3c95bd6890..8c35f9ccb68 100644
--- a/drivers/w1/w1_family.c
+++ b/drivers/w1/w1_family.c
@@ -53,7 +53,8 @@ int w1_register_family(struct w1_family *newf)
 	}
 	spin_unlock(&w1_flock);
 
-	w1_reconnect_slaves(newf);
+	/* check default devices against the new set of drivers */
+	w1_reconnect_slaves(newf, 1);
 
 	return ret;
 }
@@ -77,6 +78,9 @@ void w1_unregister_family(struct w1_family *fent)
 
 	spin_unlock(&w1_flock);
 
+	/* deatch devices using this family code */
+	w1_reconnect_slaves(fent, 0);
+
 	while (atomic_read(&fent->refcnt)) {
 		printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
 				fent->fid, atomic_read(&fent->refcnt));