Add additional examples in Documentation/spinlocks.txt
Checkpatch will throw an error if code doesn't use the correct initializers
for static spinlocks:
ERROR: Use of SPIN_LOCK_UNLOCKED is deprecated: see Documentation/spinlocks.txt
This is fine, but Documentation/spinlocks.txt isn't very clear on how to
_use_ the new initializers for static variables. To save people time in the
future, I added two small examples of how to fix old-style static
initializers to be more lockdep friendly.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/spinlocks.txt b/Documentation/spinlocks.txt
index 471e7538..619699d 100644
--- a/Documentation/spinlocks.txt
+++ b/Documentation/spinlocks.txt
@@ -5,6 +5,28 @@
__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.
