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Date:   Thu, 24 Mar 2022 15:53:59 +0800
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Subject: Re: [PATCH] IB/SA: replace usage of found with dedicated list
 iterator variable
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To:     Jakob Koschel <jakobkoschel@gmail.com>,
        Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Leon Romanovsky <leon@kernel.org>,
        =?UTF-8?Q?H=c3=a5kon_Bugge?= <haakon.bugge@oracle.com>,
        Mark Bloch <mbloch@nvidia.com>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        Mike Rapoport <rppt@kernel.org>,
        Brian Johannesmeyer <bjohannesmeyer@gmail.com>,
        Cristiano Giuffrida <c.giuffrida@vu.nl>,
        "Bos, H.J." <h.j.bos@vu.nl>
References: <20220324071124.59849-1-jakobkoschel@gmail.com>
From:   Mark Zhang <markzhang@nvidia.com>
In-Reply-To: <20220324071124.59849-1-jakobkoschel@gmail.com>
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On 3/24/2022 3:11 PM, Jakob Koschel wrote:
> External email: Use caution opening links or attachments
> 
> 
> To move the list iterator variable into the list_for_each_entry_*()
> macro in the future it should be avoided to use the list iterator
> variable after the loop body.
> 
> To *never* use the list iterator variable after the loop it was
> concluded to use a separate iterator variable instead of a
> found boolean [1].
> 
> This removes the need to use a found variable and simply checking if
> the variable was set, can determine if the break/goto was hit.
> 
> Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/
> Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
> ---
>   drivers/infiniband/core/sa_query.c | 15 +++++++--------
>   1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
> index 74ecd7456a11..74cd84045e5b 100644
> --- a/drivers/infiniband/core/sa_query.c
> +++ b/drivers/infiniband/core/sa_query.c
> @@ -1035,10 +1035,9 @@ int ib_nl_handle_resolve_resp(struct sk_buff *skb,
>                                struct netlink_ext_ack *extack)
>   {
>          unsigned long flags;
> -       struct ib_sa_query *query;
> +       struct ib_sa_query *query = NULL, *iter;
>          struct ib_mad_send_buf *send_buf;
>          struct ib_mad_send_wc mad_send_wc;
> -       int found = 0;
>          int ret;
> 
>          if ((nlh->nlmsg_flags & NLM_F_REQUEST) ||
> @@ -1046,20 +1045,20 @@ int ib_nl_handle_resolve_resp(struct sk_buff *skb,
>                  return -EPERM;
> 
>          spin_lock_irqsave(&ib_nl_request_lock, flags);
> -       list_for_each_entry(query, &ib_nl_request_list, list) {
> +       list_for_each_entry(iter, &ib_nl_request_list, list) {
>                  /*
>                   * If the query is cancelled, let the timeout routine
>                   * take care of it.
>                   */
> -               if (nlh->nlmsg_seq == query->seq) {
> -                       found = !ib_sa_query_cancelled(query);
> -                       if (found)
> -                               list_del(&query->list);
> +               if (nlh->nlmsg_seq == iter->seq) {
> +                       if (!ib_sa_query_cancelled(iter))
> +                               list_del(&iter->list);
> +                       query = iter;
>                          break;

Should it be:

if (nlh->nlmsg_seq == iter->seq) {
	if (!ib_sa_query_cancelled(iter)) {
		list_del(&iter->list);
		query = iter;
	}
	break;

>                  }
>          }
> 
> -       if (!found) {
> +       if (!query) {
>                  spin_unlock_irqrestore(&ib_nl_request_lock, flags);
>                  goto resp_out;
>          }
> 
> base-commit: f443e374ae131c168a065ea1748feac6b2e76613
> --
> 2.25.1
>