forked from luck/tmp_suning_uos_patched
[PATCH] lockdep: add more rwsem.h documentation
Add more documentation to rwsem.h. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -61,12 +61,25 @@ extern void downgrade_write(struct rw_semaphore *sem);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/*
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* nested locking:
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* nested locking. NOTE: rwsems are not allowed to recurse
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* (which occurs if the same task tries to acquire the same
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* lock instance multiple times), but multiple locks of the
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* same lock class might be taken, if the order of the locks
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* is always the same. This ordering rule can be expressed
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* to lockdep via the _nested() APIs, but enumerating the
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* subclasses that are used. (If the nesting relationship is
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* static then another method for expressing nested locking is
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* the explicit definition of lock class keys and the use of
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* lockdep_set_class() at lock initialization time.
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* See Documentation/lockdep-design.txt for more details.)
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*/
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extern void down_read_nested(struct rw_semaphore *sem, int subclass);
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extern void down_write_nested(struct rw_semaphore *sem, int subclass);
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/*
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* Take/release a lock when not the owner will release it:
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* Take/release a lock when not the owner will release it.
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*
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* [ This API should be avoided as much as possible - the
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* proper abstraction for this case is completions. ]
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*/
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extern void down_read_non_owner(struct rw_semaphore *sem);
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extern void up_read_non_owner(struct rw_semaphore *sem);
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