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Date:   Tue, 19 Nov 2019 16:31:38 -0400
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     rao Shoaib <rao.shoaib@oracle.com>
Cc:     monis@mellanox.com, dledford@redhat.com, sean.hefty@intel.com,
        hal.rosenstock@gmail.com, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] Introduce maximum WQE size to check limits
Message-ID: <20191119203138.GA13145@ziepe.ca>
References: <1574106879-19211-1-git-send-email-rao.shoaib@oracle.com>
 <1574106879-19211-2-git-send-email-rao.shoaib@oracle.com>
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On Mon, Nov 18, 2019 at 11:54:38AM -0800, rao Shoaib wrote:
> From: Rao Shoaib <rao.shoaib@oracle.com>
> 
> Introduce maximum WQE size to impose limits on max SGE's and inline data
> 
> Signed-off-by: Rao Shoaib <rao.shoaib@oracle.com>
>  drivers/infiniband/sw/rxe/rxe_param.h | 3 ++-
>  drivers/infiniband/sw/rxe/rxe_qp.c    | 7 +++++--
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_param.h b/drivers/infiniband/sw/rxe/rxe_param.h
> index 1b596fb..31fb5c7 100644
> +++ b/drivers/infiniband/sw/rxe/rxe_param.h
> @@ -68,7 +68,6 @@ enum rxe_device_param {
>  	RXE_HW_VER			= 0,
>  	RXE_MAX_QP			= 0x10000,
>  	RXE_MAX_QP_WR			= 0x4000,
> -	RXE_MAX_INLINE_DATA		= 400,
>  	RXE_DEVICE_CAP_FLAGS		= IB_DEVICE_BAD_PKEY_CNTR
>  					| IB_DEVICE_BAD_QKEY_CNTR
>  					| IB_DEVICE_AUTO_PATH_MIG
> @@ -79,7 +78,9 @@ enum rxe_device_param {
>  					| IB_DEVICE_RC_RNR_NAK_GEN
>  					| IB_DEVICE_SRQ_RESIZE
>  					| IB_DEVICE_MEM_MGT_EXTENSIONS,
> +	RXE_MAX_WQE_SIZE		= 0x2d0, /* For RXE_MAX_SGE */

This shouldn't just be a random constant, I think you are trying to
say:

  RXE_MAX_WQE_SIZE = sizeof(struct rxe_send_wqe) + sizeof(struct ib_sge)*RXE_MAX_SGE

Just say that

>  	RXE_MAX_SGE			= 32,
> +	RXE_MAX_INLINE_DATA		= RXE_MAX_WQE_SIZE,

This is mixed up now, it should be

  RXE_MAX_INLINE_DATA = RXE_MAX_WQE_SIZE - sizeof(rxe_send_wqe)

> diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c
> index aeea994..323e43d 100644
> +++ b/drivers/infiniband/sw/rxe/rxe_qp.c
> @@ -78,9 +78,12 @@ static int rxe_qp_chk_cap(struct rxe_dev *rxe, struct ib_qp_cap *cap,
>  		}
>  	}
>  
> -	if (cap->max_inline_data > rxe->max_inline_data) {
> +	if (cap->max_inline_data >
> +	    rxe->max_inline_data - sizeof(struct rxe_send_wqe)) {
>  		pr_warn("invalid max inline data = %d > %d\n",
> -			cap->max_inline_data, rxe->max_inline_data);
> +			cap->max_inline_data,
> +			rxe->max_inline_data -
> +			    (u32)sizeof(struct rxe_send_wqe));

Then this isn't needed

And this code in the other patch:

+	wqe_size = max_t(int, init->cap.max_send_sge * sizeof(struct ib_sge),
+			 init->cap.max_inline_data);
+	qp->sq.max_sge = wqe_size/sizeof(struct ib_sge);
+	qp->sq.max_inline = wqe_size;

Makes sense as both max_inline_data and 'init->cap.max_send_sge *
sizeof(struct ib_sge)' are exclusive of the wqe header

Jason