list.h: add list_is_singular()
Add list_is_singular() to check a list has just one entry. list_is_singular() is useful to check whether a list_head which have been temporarily allocated for listing objects can be released or not. Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -319,6 +319,15 @@ static inline int list_empty_careful(const struct list_head *head)
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return (next == head) && (next == head->prev);
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}
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/**
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* list_is_singular - tests whether a list has just one entry.
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* @head: the list to test.
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*/
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static inline int list_is_singular(const struct list_head *head)
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{
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return !list_empty(head) && (head->next == head->prev);
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}
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static inline void __list_splice(struct list_head *list,
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struct list_head *head)
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{
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