Linux-RDMA Archive on lore.kernel.org
 help / color / Atom feed
From: Zhu Yanjun <zyjzyj2000@gmail.com>
To: Fan Yang <yangfan.fan@bytedance.com>
Cc: Zhu Yanjun <yanjunz@mellanox.com>, linux-rdma@vger.kernel.org
Subject: Re: [PATCH] RDMA/rxe: fix retry forever when rnr_retry >= 7
Date: Thu, 23 Jul 2020 23:42:56 +0800
Message-ID: <CAD=hENdG_0hdcRQk+sH6HyuOROM-U9_n2QahipgmOdESQDso3g@mail.gmail.com> (raw)
In-Reply-To: <D1A472F9-6618-41A2-9CA8-B5231BD03D63@bytedance.com>

On Thu, Jul 23, 2020 at 9:28 PM Fan Yang <yangfan.fan@bytedance.com> wrote:
>
> Currently when an error occurs and the completion state becomes
> COMPST_RNR_RETRY, qp->comp.rnr_retry is only decreased when
> qp->comp.rnr_retry != 7.
>
> If the user happens to config the rnr retry count to be >= 7, the
> driver will retry forever, instead of exposing IB_WC_RNR_RETRY_EXC_ERR.

Please read the following from IB specification

"

The RNR NAK retry counter is decremented each time the responder returns

an RNR NAK. If the requester’s RNR NAK retry counter is zero, and
an RNR NAK packet is received, an RNR NAK retry error occurs. Each
time an RNR NAK is cleared (i.e., an acknowledge message other than
an RNR NAK is returned), the retry counter is reloaded. An exception to
the following is if the RNR NAK retry counter is set to 7. This value indicates

infinite retry and the counter is not decremented.

"


>
> ---
>  drivers/infiniband/sw/rxe/rxe_comp.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
> index 4bc88708b355..16c1870b6482 100644
> --- a/drivers/infiniband/sw/rxe/rxe_comp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_comp.c
> @@ -745,8 +745,7 @@ int rxe_completer(void *arg)
>
>                 case COMPST_RNR_RETRY:
>                         if (qp->comp.rnr_retry > 0) {
> -                               if (qp->comp.rnr_retry != 7)
> -                                       qp->comp.rnr_retry--;
> +                               qp->comp.rnr_retry--;
>
>                                 qp->req.need_retry = 1;
>                                 pr_debug("qp#%d set rnr nak timer\n",
> --
> 2.27.0
>
>

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-23 13:25 Fan Yang
2020-07-23 15:42 ` Zhu Yanjun [this message]
2020-07-24 14:04   ` [External] " 杨帆
2020-07-24 14:18     ` Jason Gunthorpe
2020-07-24 14:20       ` Fan Yang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAD=hENdG_0hdcRQk+sH6HyuOROM-U9_n2QahipgmOdESQDso3g@mail.gmail.com' \
    --to=zyjzyj2000@gmail.com \
    --cc=linux-rdma@vger.kernel.org \
    --cc=yangfan.fan@bytedance.com \
    --cc=yanjunz@mellanox.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-RDMA Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-rdma/0 linux-rdma/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-rdma linux-rdma/ https://lore.kernel.org/linux-rdma \
		linux-rdma@vger.kernel.org
	public-inbox-index linux-rdma

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-rdma


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git