X-Git-Url: http://pilppa.org/gitweb/?a=blobdiff_plain;f=Documentation%2Fspinlocks.txt;h=619699dde5938b64c6d63e1059cf0ed702c128af;hb=22c1c7879d60d1419672ff9f6d162e89fe3cc1a1;hp=c2122996631e4d413fffe6be3d1173f827a8649c;hpb=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2;p=linux-2.6-omap-h63xx.git

diff --git a/Documentation/spinlocks.txt b/Documentation/spinlocks.txt
index c2122996631..619699dde59 100644
--- a/Documentation/spinlocks.txt
+++ b/Documentation/spinlocks.txt
@@ -1,7 +1,34 @@
-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;
@@ -9,18 +36,15 @@ removed soon. So for any new code dynamic initialization should be used:
    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.
 
 -----------------------