[dm-devel] [PATCH v3 2/6] list_bl: Add hlist_bl_add_before/behind helpers

[Paul E. McKenney]

On Sun, Mar 17, 2019 at 02:22:54PM +0200, Nikos Tsironis wrote:
> Add hlist_bl_add_before/behind helpers to add an element before/after an
> existing element in a bl_list.
> 
> Signed-off-by: Nikos Tsironis <ntsironis at arrikto.com>
> Signed-off-by: Ilias Tsitsimpis <iliastsi at arrikto.com>

On both this and the previous patch, the double signed-off-by lines
are a bit strange.  You might be wanting Co-developed-by, but please
see Documentation/process/submitting-patches.rst.

Other than that:

Reviewed-by: Paul E. McKenney <paulmck at linux.ibm.com>

> ---
>  include/linux/list_bl.h | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
> index 3fc2cc57ba1b..ae1b541446c9 100644
> --- a/include/linux/list_bl.h
> +++ b/include/linux/list_bl.h
> @@ -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;
> -- 
> 2.11.0
>