RCU, rculist.h: fix list iterators
RCU list iterators: should prefetch ever be optimised out with no side-effects, the current version will lose the barrier completely. Pointed-out-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -180,31 +180,14 @@ static inline void list_splice_init_rcu(struct list_head *list,
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* as long as the traversal is guarded by rcu_read_lock().
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*/
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#define list_for_each_rcu(pos, head) \
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for (pos = (head)->next; \
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prefetch(rcu_dereference(pos)->next), pos != (head); \
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pos = pos->next)
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for (pos = rcu_dereference((head)->next); \
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prefetch(pos->next), pos != (head); \
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pos = rcu_dereference(pos->next))
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#define __list_for_each_rcu(pos, head) \
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for (pos = (head)->next; \
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rcu_dereference(pos) != (head); \
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pos = pos->next)
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/**
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* list_for_each_safe_rcu
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* @pos: the &struct list_head to use as a loop cursor.
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* @n: another &struct list_head to use as temporary storage
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* @head: the head for your list.
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*
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* Iterate over an rcu-protected list, safe against removal of list entry.
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*
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* This list-traversal primitive may safely run concurrently with
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* the _rcu list-mutation primitives such as list_add_rcu()
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* as long as the traversal is guarded by rcu_read_lock().
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*/
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#define list_for_each_safe_rcu(pos, n, head) \
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for (pos = (head)->next; \
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n = rcu_dereference(pos)->next, pos != (head); \
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pos = n)
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for (pos = rcu_dereference((head)->next); \
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pos != (head); \
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pos = rcu_dereference(pos->next))
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/**
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* list_for_each_entry_rcu - iterate over rcu list of given type
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@ -217,10 +200,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
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* as long as the traversal is guarded by rcu_read_lock().
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*/
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#define list_for_each_entry_rcu(pos, head, member) \
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for (pos = list_entry((head)->next, typeof(*pos), member); \
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prefetch(rcu_dereference(pos)->member.next), \
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&pos->member != (head); \
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pos = list_entry(pos->member.next, typeof(*pos), member))
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for (pos = list_entry(rcu_dereference((head)->next), typeof(*pos), member); \
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prefetch(pos->member.next), &pos->member != (head); \
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pos = list_entry(rcu_dereference(pos->member.next), typeof(*pos), member))
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/**
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@ -235,9 +217,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
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* as long as the traversal is guarded by rcu_read_lock().
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*/
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#define list_for_each_continue_rcu(pos, head) \
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for ((pos) = (pos)->next; \
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prefetch(rcu_dereference((pos))->next), (pos) != (head); \
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(pos) = (pos)->next)
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for ((pos) = rcu_dereference((pos)->next); \
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prefetch((pos)->next), (pos) != (head); \
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(pos) = rcu_dereference((pos)->next))
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/**
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* hlist_del_rcu - deletes entry from hash list without re-initialization
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@ -382,10 +364,10 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
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* as long as the traversal is guarded by rcu_read_lock().
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*/
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#define hlist_for_each_entry_rcu(tpos, pos, head, member) \
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for (pos = (head)->first; \
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rcu_dereference(pos) && ({ prefetch(pos->next); 1; }) && \
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for (pos = rcu_dereference((head)->first); \
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pos && ({ prefetch(pos->next); 1; }) && \
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({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
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pos = pos->next)
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pos = rcu_dereference(pos->next))
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#endif /* __KERNEL__ */
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#endif
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