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list_bl: Add hlist_bl_add_before/behind helpers 

Add hlist_bl_add_before/behind helpers to add an element before/after an
existing element in a bl_list.

Co-developed-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Nikos Tsironis 2019-03-17 14:22:54 +02:00 committed by Mike Snitzer
parent ae325dcd19
commit 34191ae816
1 changed files with 26 additions and 0 deletions
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26
include/linux/list_bl.h
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@ -86,6 +86,32 @@ static inline void hlist_bl_add_head(struct hlist_bl_node *n,
hlist_bl_set_first(h, n);
}
static inline void hlist_bl_add_before(struct hlist_bl_node *n,
struct hlist_bl_node *next)
{
struct hlist_bl_node **pprev = next->pprev;
n->pprev = pprev;
n->next = next;
next->pprev = &n->next;
/* pprev may be `first`, so be careful not to lose the lock bit */
WRITE_ONCE(*pprev,
(struct hlist_bl_node *)
((uintptr_t)n | ((uintptr_t)*pprev & LIST_BL_LOCKMASK)));
}
static inline void hlist_bl_add_behind(struct hlist_bl_node *n,
struct hlist_bl_node *prev)
{
n->next = prev->next;
n->pprev = &prev->next;
prev->next = n;
if (n->next)
n->next->pprev = &n->next;
}
static inline void __hlist_bl_del(struct hlist_bl_node *n)
{
struct hlist_bl_node *next = n->next;