From: Mark Fasheh <mfasheh@suse.com>
Date: Thu, 10 Apr 2008 20:55:21 +0000 (-0700)
Subject: Add additional examples in Documentation/spinlocks.txt
X-Git-Tag: v2.6.25-rc9~1^2
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=14dadf1d5eb5bea2dd115852cfee880505c1c169;p=cascardo%2Flinux.git

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 471e75389778..619699dde593 100644
--- a/Documentation/spinlocks.txt
+++ b/Documentation/spinlocks.txt
@@ -5,6 +5,28 @@ 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.