Re: [PATCH] svcrdma: remove rdma_create_qp() failure recovery logic

[J. Bruce Fields]

Thanks, applying for 3.17.--b.

On Thu, Jul 31, 2014 at 03:26:07PM -0500, Steve Wise wrote:
> In svc_rdma_accept(), if rdma_create_qp() fails, there is useless
> logic to try and call rdma_create_qp() again with reduced sge depths.
> The assumption, I guess, was that perhaps the initial sge depths
> chosen were too big.  However they initial depths are selected based
> on the rdma device attribute max_sge returned from ib_query_device().
> If rdma_create_qp() fails, it would not be because the max_send_sge and
> max_recv_sge values passed in exceed the device's max.  So just remove
> this code.
> 
> Signed-off-by: Steve Wise 
> ---
> 
>  net/sunrpc/xprtrdma/svc_rdma_transport.c |   19 ++-
>  1 files changed, 2 insertions(+), 17 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c 
> b/net/sunrpc/xprtrdma/svc_rdma_transport.c
> index e7323fb..282a43b 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
> @@ -942,23 +942,8 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt 
> *xprt)
>  
>   ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd, &qp_attr);
>   if (ret) {
> - /*
> -  * XXX: This is a hack. We need a xx_request_qp interface
> -  * that will adjust the qp_attr's with a best-effort
> -  * number
> -  */
> - qp_attr.cap.max_send_sge -= 2;
> - qp_attr.cap.max_recv_sge -= 2;
> - ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd,
> -  &qp_attr);
> - if (ret) {
> - dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
> - goto errout;
> - }
> - newxprt->sc_max_sge = qp_attr.cap.max_send_sge;
> - newxprt->sc_max_sge = qp_attr.cap.max_recv_sge;
> - newxprt->sc_sq_depth = qp_attr.cap.max_send_wr;
> - newxprt->sc_max_requests = qp_attr.cap.max_recv_wr;
> + dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
> + goto errout;
>   }
>   newxprt->sc_qp = newxprt->sc_cm_id->qp;
>  
> 
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Re: [PATCH] svcrdma: remove rdma_create_qp() failure recovery logic

[Steve Wise]

Tested over cxgb4 and mlx4.

Steve.
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[PATCH] svcrdma: remove rdma_create_qp() failure recovery logic

[Steve Wise]

In svc_rdma_accept(), if rdma_create_qp() fails, there is useless
logic to try and call rdma_create_qp() again with reduced sge depths.
The assumption, I guess, was that perhaps the initial sge depths
chosen were too big.  However they initial depths are selected based
on the rdma device attribute max_sge returned from ib_query_device().
If rdma_create_qp() fails, it would not be because the max_send_sge and
max_recv_sge values passed in exceed the device's max.  So just remove
this code.

Signed-off-by: Steve Wise 
---

 net/sunrpc/xprtrdma/svc_rdma_transport.c |   19 ++-
 1 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c 
b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index e7323fb..282a43b 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -942,23 +942,8 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt 
*xprt)
 
ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd, &qp_attr);
if (ret) {
-   /*
-* XXX: This is a hack. We need a xx_request_qp interface
-* that will adjust the qp_attr's with a best-effort
-* number
-*/
-   qp_attr.cap.max_send_sge -= 2;
-   qp_attr.cap.max_recv_sge -= 2;
-   ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd,
-&qp_attr);
-   if (ret) {
-   dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
-   goto errout;
-   }
-   newxprt->sc_max_sge = qp_attr.cap.max_send_sge;
-   newxprt->sc_max_sge = qp_attr.cap.max_recv_sge;
-   newxprt->sc_sq_depth = qp_attr.cap.max_send_wr;
-   newxprt->sc_max_requests = qp_attr.cap.max_recv_wr;
+   dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
+   goto errout;
}
newxprt->sc_qp = newxprt->sc_cm_id->qp;
 

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