netdev - Re: [PATCH] RDS: Simplify code

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Message-ID: <26832741-da10-7581-11d2-d88e6df43c4e@oracle.com>
Date:   Mon, 5 Sep 2016 17:22:06 -0700
From:   "santosh.shilimkar@...cle.com" <santosh.shilimkar@...cle.com>
To:     Leon Romanovsky <leon@...nel.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     davem@...emloft.net, linux-rdma@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] RDS: Simplify code

On 9/4/16 11:23 AM, Leon Romanovsky wrote:
> On Sun, Sep 04, 2016 at 05:57:20PM +0200, Christophe JAILLET wrote:
>> Le 04/09/2016 à 14:20, Leon Romanovsky a écrit :
>>> On Sat, Sep 03, 2016 at 07:33:29AM +0200, Christophe JAILLET wrote:
>>>> Calling 'list_splice' followed by 'INIT_LIST_HEAD' is equivalent to
>>>> 'list_splice_init'.
>>> It is not 100% accurate
>>>
>>> list_splice(y, z)
>>> INIT_LIST_HEAD(y)
>>>
>>> ==>
>>>
>>> if (!list_empty(y))
>>>      __list_splice(y, z, z>next);
>>> INIT_LIST_HEAD(y)
>>>
>>> and not
>>>
>>> if (!list_empty(y)) {
>>>      __list_splice(y, z, z>next);
>>>      INIT_LIST_HEAD(y)
>>> }
>>>
>>> as list_splice_init will do.
>>>
>> You are right but if you dig further you will see that calling
>> INIT_LIST_HEAD on an empty list is a no-op (AFAIK).
>> And if this list was not already correctly initialized, then you would have
>> some other troubles.
>
> Thank you for the suggestion,
> It looks like the code after that can be skipped in case of loop_conns
> list is empty, the tmp_list will be empty too.
>
> 174         list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
> 175                 WARN_ON(lc->conn->c_passive);
> 176                 rds_conn_destroy(lc->conn);
> 177         }
>

Thanks for trying. As already pointed, your change doesn't simplify
much rather change the behavior. The loop cursor already takes care
of list empty case. I don't see any reason to change that code.

Regards,
Santosh