On Tue, May 01, 2018 at 01:11:29PM +1000, NeilBrown wrote: > > list_for_each_entry_from_rcu() is an RCU version of > list_for_each_entry_from(). It walks a linked list under rcu > protection, from a given start point. > > It is similar to list_for_each_entry_continue_rcu() but starts *at* > the given position rather than *after* it. > > Naturally, the start point must be known to be in the list. > > Also update the documentation for list_for_each_entry_continue_rcu() > to match the documentation for the new list_for_each_entry_from_rcu(), > and add list_for_each_entry_from_rcu() and the already existing > hlist_for_each_entry_from_rcu() to section 7 of whatisRCU.txt. > > Signed-off-by: NeilBrown <neilb@xxxxxxxx> I am guessing that it would be more convenient for you to carry this with the patches using it, so: Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> If not, please let me know. Thanx, Paul > --- > Documentation/RCU/whatisRCU.txt | 2 ++ > include/linux/rculist.h | 32 +++++++++++++++++++++++++++++++- > 2 files changed, 33 insertions(+), 1 deletion(-) > > diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt > index a27fbfb0efb8..b7d38bd212d2 100644 > --- a/Documentation/RCU/whatisRCU.txt > +++ b/Documentation/RCU/whatisRCU.txt > @@ -814,11 +814,13 @@ RCU list traversal: > list_next_rcu > list_for_each_entry_rcu > list_for_each_entry_continue_rcu > + list_for_each_entry_from_rcu > hlist_first_rcu > hlist_next_rcu > hlist_pprev_rcu > hlist_for_each_entry_rcu > hlist_for_each_entry_rcu_bh > + hlist_for_each_entry_from_rcu > hlist_for_each_entry_continue_rcu > hlist_for_each_entry_continue_rcu_bh > hlist_nulls_first_rcu > diff --git a/include/linux/rculist.h b/include/linux/rculist.h > index 127f534fec94..4786c2235b98 100644 > --- a/include/linux/rculist.h > +++ b/include/linux/rculist.h > @@ -396,13 +396,43 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, > * @member: the name of the list_head within the struct. > * > * Continue to iterate over list of given type, continuing after > - * the current position. > + * the current position which must have been in the list when the RCU read > + * lock was taken. > + * This would typically require either that you obtained the node from a > + * previous walk of the list in the same RCU read-side critical section, or > + * that you held some sort of non-RCU reference (such as a reference count) > + * to keep the node alive *and* in the list. > + * > + * This iterator is similar to list_for_each_entry_from_rcu() except > + * this starts after the given position and that one starts at the given > + * position. > */ > #define list_for_each_entry_continue_rcu(pos, head, member) \ > for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \ > &pos->member != (head); \ > pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) > > +/** > + * list_for_each_entry_from_rcu - iterate over a list from current point > + * @pos: the type * to use as a loop cursor. > + * @head: the head for your list. > + * @member: the name of the list_node within the struct. > + * > + * Iterate over the tail of a list starting from a given position, > + * which must have been in the list when the RCU read lock was taken. > + * This would typically require either that you obtained the node from a > + * previous walk of the list in the same RCU read-side critical section, or > + * that you held some sort of non-RCU reference (such as a reference count) > + * to keep the node alive *and* in the list. > + * > + * This iterator is similar to list_for_each_entry_continue_rcu() except > + * this starts from the given position and that one starts from the position > + * after the given position. > + */ > +#define list_for_each_entry_from_rcu(pos, head, member) \ > + for (; &(pos)->member != (head); \ > + pos = list_entry_rcu(pos->member.next, typeof(*(pos)), member)) > + > /** > * hlist_del_rcu - deletes entry from hash list without re-initialization > * @n: the element to delete from the hash list. > -- > 2.14.0.rc0.dirty > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
