Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6beeac...
Commit:     6beeac76f5f96590fb751af5e138fbc3f62e8460
Parent:     93686ae8357c1b1e37e8dfc96547f807e7a93b4b
Author:     Andrea Arcangeli <andrea@qumranet.com>
AuthorDate: Mon Jul 28 15:46:22 2008 -0700
Committer:  Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Mon Jul 28 16:30:20 2008 -0700

    mmu-notifiers: add list_del_init_rcu()
    
    Introduce list_del_init_rcu() and document it.
    
    Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
    Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Christoph Lameter <cl@linux-foundation.org>
    Cc: Jack Steiner <steiner@sgi.com>
    Cc: Robin Holt <holt@sgi.com>
    Cc: Nick Piggin <npiggin@suse.de>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Kanoj Sarcar <kanojsarcar@yahoo.com>
    Cc: Roland Dreier <rdreier@cisco.com>
    Cc: Steve Wise <swise@opengridcomputing.com>
    Cc: Avi Kivity <avi@qumranet.com>
    Cc: Hugh Dickins <hugh@veritas.com>
    Cc: Rusty Russell <rusty@rustcorp.com.au>
    Cc: Anthony Liguori <aliguori@us.ibm.com>
    Cc: Chris Wright <chrisw@redhat.com>
    Cc: Marcelo Tosatti <marcelo@kvack.org>
    Cc: Eric Dumazet <dada1@cosmosbay.com>
    Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
    Cc: Izik Eidus <izike@qumranet.com>
    Cc: Anthony Liguori <aliguori@us.ibm.com>
    Cc: Rik van Riel <riel@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/rculist.h |   28 ++++++++++++++++++++++++++++
 1 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index b0f39be..eb4443c 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -98,6 +98,34 @@ static inline void list_del_rcu(struct list_head *entry)
 }
 
 /**
+ * hlist_del_init_rcu - deletes entry from hash list with re-initialization
+ * @n: the element to delete from the hash list.
+ *
+ * Note: list_unhashed() on the node return true after this. It is
+ * useful for RCU based read lockfree traversal if the writer side
+ * must know if the list entry is still hashed or already unhashed.
+ *
+ * In particular, it means that we can not poison the forward pointers
+ * that may still be used for walking the hash list and we can only
+ * zero the pprev pointer so list_unhashed() will return true after
+ * this.
+ *
+ * The caller must take whatever precautions are necessary (such as
+ * holding appropriate locks) to avoid racing with another
+ * list-mutation primitive, such as hlist_add_head_rcu() or
+ * hlist_del_rcu(), running on this same list.  However, it is
+ * perfectly legal to run concurrently with the _rcu list-traversal
+ * primitives, such as hlist_for_each_entry_rcu().
+ */
+static inline void hlist_del_init_rcu(struct hlist_node *n)
+{
+	if (!hlist_unhashed(n)) {
+		__hlist_del(n);
+		n->pprev = NULL;
+	}
+}
+
+/**
  * list_replace_rcu - replace old entry by new one
  * @old : the element to be replaced
  * @new : the new element to insert
--
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