-UPDATE March 21 2005 Amit Gud <gud@eth.net>
+SPIN_LOCK_UNLOCKED and RW_LOCK_UNLOCKED defeat lockdep state tracking and
+are hence deprecated.
-Macros SPIN_LOCK_UNLOCKED and RW_LOCK_UNLOCKED are deprecated and will be
-removed soon. So for any new code dynamic initialization should be used:
+Please use DEFINE_SPINLOCK()/DEFINE_RWLOCK() or
+__SPIN_LOCK_UNLOCKED()/__RW_LOCK_UNLOCKED() as appropriate for static
+initialization.
+
+Most of the time, you can simply turn:
+
+ static spinlock_t xxx_lock = SPIN_LOCK_UNLOCKED;
+
+into:
+
+ static DEFINE_SPINLOCK(xxx_lock);
+
+Static structure member variables go from:
+
+ struct foo bar {
+ .lock = SPIN_LOCK_UNLOCKED;
+ };
+
+to:
+
+ struct foo bar {
+ .lock = __SPIN_LOCK_UNLOCKED(bar.lock);
+ };
+
+Declaration of static rw_locks undergo a similar transformation.
+
+Dynamic initialization, when necessary, may be performed as
+demonstrated below.
spinlock_t xxx_lock;
rwlock_t xxx_rw_lock;
static int __init xxx_init(void)
{
spin_lock_init(&xxx_lock);
- rw_lock_init(&xxx_rw_lock);
+ rwlock_init(&xxx_rw_lock);
...
}
module_init(xxx_init);
-Reasons for deprecation
- - it hurts automatic lock validators
- - it becomes intrusive for the realtime preemption patches
-
-Following discussion is still valid, however, with the dynamic initialization
-of spinlocks instead of static.
+The following discussion is still valid, however, with the dynamic
+initialization of spinlocks or with DEFINE_SPINLOCK, etc., used
+instead of SPIN_LOCK_UNLOCKED.
-----------------------