From 017f021c7e5fe3f82ccc5cbb7b1750e66e00f527 Mon Sep 17 00:00:00 2001
From: "Ed L. Cashin" <ecashin@coraid.com>
Date: Sun, 15 Jul 2007 23:41:50 -0700
Subject: [PATCH] docs: static initialization of spinlocks is OK
Static initialization of spinlocks is preferable to dynamic initialization
when it is practical. This patch updates documentation for consistency
with comments in spinlock_types.h.
Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Documentation/spinlocks.txt | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/Documentation/spinlocks.txt b/Documentation/spinlocks.txt
index a661d684768e9..471e75389778e 100644
--- a/Documentation/spinlocks.txt
+++ b/Documentation/spinlocks.txt
@@ -1,7 +1,12 @@
-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.
+
+Dynamic initialization, when necessary, may be performed as
+demonstrated below.
spinlock_t xxx_lock;
rwlock_t xxx_rw_lock;
@@ -15,12 +20,9 @@ removed soon. So for any new code dynamic initialization should be used:
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.
-----------------------
--
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