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docs: static initialization of spinlocks is OK

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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>
This commit is contained in:
Ed L. Cashin 2007-07-15 23:41:50 -07:00 committed by Linus Torvalds
parent 7e7d136e9e
commit 017f021c7e
1 changed files with 11 additions and 9 deletions
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20
Documentation/spinlocks.txt
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@ -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 Please use DEFINE_SPINLOCK()/DEFINE_RWLOCK() or
removed soon. So for any new code dynamic initialization should be used: __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; spinlock_t xxx_lock;
rwlock_t xxx_rw_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); module_init(xxx_init);
Reasons for deprecation The following discussion is still valid, however, with the dynamic
- it hurts automatic lock validators initialization of spinlocks or with DEFINE_SPINLOCK, etc., used
- it becomes intrusive for the realtime preemption patches instead of SPIN_LOCK_UNLOCKED.
Following discussion is still valid, however, with the dynamic initialization
of spinlocks instead of static.
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