Commit 14dadf1d authored Apr 10, 2008 by Mark Fasheh Committed by Jonathan Corbet Apr 11, 2008

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>

parent d396c5f1

Documentation/spinlocks.txt

+22 −0

Original line number	Diff line number	Diff line
		@@ -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.