Messages in this thread |  | | Subject | Re: [PATCH v2 2/3] llist: add a safe version of llist_for_each_entry | From | Huang Ying <> | Date | Tue, 11 Dec 2012 08:51:24 +0800 |
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On Mon, 2012-12-10 at 18:24 +0100, Roger Pau Monne wrote: > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Konrad Rzeszutek Wilk <konrad@kernel.org> > --- > include/linux/llist.h | 27 +++++++++++++++++++++++++++ > 1 files changed, 27 insertions(+), 0 deletions(-) > > diff --git a/include/linux/llist.h b/include/linux/llist.h > index a5199f6..f611cd8 100644 > --- a/include/linux/llist.h > +++ b/include/linux/llist.h > @@ -125,6 +125,33 @@ static inline void init_llist_head(struct llist_head *list) > (pos) = llist_entry((pos)->member.next, typeof(*(pos)), member)) > > /** > + * llist_for_each_entry_safe - safely iterate over some deleted entries of > + * lock-less list of given type > + * @pos: the type * to use as a loop cursor. > + * @n: the &struct llist_node to use as a temporary loop cursor > + * @node: the fist entry of deleted list entries. > + * @member: the name of the llist_node with the struct. > + * > + * In general, some entries of the lock-less list can be traversed > + * safely only after being removed from list, so start with an entry > + * instead of list head. > + * > + * If being used on entries deleted from lock-less list directly, the > + * traverse order is from the newest to the oldest added entry. If > + * you want to traverse from the oldest to the newest, you must > + * reverse the order by yourself before traversing. > + * > + * n is used to store a reference to the next item llist_node, so > + * pos can be freed while iterating. > + */ > +#define llist_for_each_entry_safe(pos, n, node, member) \ > + for ((pos) = llist_entry((node), typeof(*(pos)), member), \ > + (n) = (pos)->member.next; \
If node == NULL, (pos)->member.next will trigger NULL reference.
Best Regards, Huang Ying
> + &(pos)->member != NULL; \ > + (pos) = llist_entry(n, typeof(*(pos)), member), \ > + (n) = (&(pos)->member != NULL) ? (pos)->member.next : NULL) > + > +/** > * llist_empty - tests whether a lock-less list is empty > * @head: the list to test > *
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