Re: [RESEND PATCH] bcache: Don't reinvent the wheel but use existing llist API

[Coly Li <i@coly.li>]

On 2017/8/8 下午12:12, Byungchul Park wrote:
> On Mon, Aug 07, 2017 at 06:18:35PM +0800, Coly Li wrote:
>> On 2017/8/7 下午4:38, Byungchul Park wrote:
>>> Although llist provides proper APIs, they are not used. Make them used.
>>>
>>> Signed-off-by: Byungchul Park <byungchul.park@lge.com
>> Only have a question about why not using llist_for_each_entry(), it's
> 
> Hello,
> 
> The reason is to keep the original logic unchanged. The logic already
> does as if it's the safe version against removal.
> 
>> still OK with llist_for_each_entry_safe(). The rested part is good to me.
>>
>> Acked-by: Coly Li <colyli@suse.de>
>>
>>> ---
>>>  drivers/md/bcache/closure.c | 17 +++--------------
>>>  1 file changed, 3 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/drivers/md/bcache/closure.c b/drivers/md/bcache/closure.c
>>> index 864e673..1841d03 100644
>>> --- a/drivers/md/bcache/closure.c
>>> +++ b/drivers/md/bcache/closure.c
>>> @@ -64,27 +64,16 @@ void closure_put(struct closure *cl)
>>>  void __closure_wake_up(struct closure_waitlist *wait_list)
>>>  {
>>>  	struct llist_node *list;
>>> -	struct closure *cl;
>>> +	struct closure *cl, *t;
>>>  	struct llist_node *reverse = NULL;
>>>  
>>>  	list = llist_del_all(&wait_list->list);
>>>  
>>>  	/* We first reverse the list to preserve FIFO ordering and fairness */
>>> -
>>> -	while (list) {
>>> -		struct llist_node *t = list;
>>> -		list = llist_next(list);
>>> -
>>> -		t->next = reverse;
>>> -		reverse = t;
>>> -	}
>>> +	reverse = llist_reverse_order(list);
>>>  
>>>  	/* Then do the wakeups */
>>> -
>>> -	while (reverse) {
>>> -		cl = container_of(reverse, struct closure, list);
>>> -		reverse = llist_next(reverse);
>>> -
>>> +	llist_for_each_entry_safe(cl, t, reverse, list) {
>>
>> Just wondering why not using llist_for_each_entry(), or you use the
>> _safe version on purpose ?
> 
> If I use llist_for_each_entry(), then it would change the original
> behavior. Is it ok?
> 

I feel llist_for_each_entry() keeps the original behavior, and variable
't' can be removed. Anyway, either llist_for_each_entry() or
llist_for_each_entry_safe() works correctly and well here. Any one you
use is OK to me, thanks for your informative reply :-)



-- 
Coly Li