linux-kernel - Re: [for-next PATCH v6 09/10] RDMA/cm: Make QP FLUSHABLE

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Message-ID: <Y3ziLoRuXFIOpnnl@nvidia.com>
Date:   Tue, 22 Nov 2022 10:52:30 -0400
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Li Zhijian <lizhijian@...itsu.com>
Cc:     zyjzyj2000@...il.com, leon@...nel.org,
        Bob Pearson <rpearsonhpe@...il.com>,
        linux-rdma@...r.kernel.org, Mark Bloch <mbloch@...dia.com>,
        Tom Talpey <tom@...pey.com>, tomasz.gromadzki@...el.com,
        Dan Williams <dan.j.williams@...el.com>,
        Xiao Yang <yangx.jy@...itsu.com>, y-goto@...itsu.com,
        linux-kernel@...r.kernel.org
Subject: Re: [for-next PATCH v6 09/10] RDMA/cm: Make QP FLUSHABLE

On Wed, Nov 16, 2022 at 04:19:50PM +0800, Li Zhijian wrote:
> It enables flushable access flag for qp
> 
> Reviewed-by: Zhu Yanjun <zyjzyj2000@...il.com>
> Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
> ---
> V5: new patch, inspired by Bob
> ---
>  drivers/infiniband/core/cm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
> index 1f9938a2c475..58837aac980b 100644
> --- a/drivers/infiniband/core/cm.c
> +++ b/drivers/infiniband/core/cm.c
> @@ -4096,7 +4096,8 @@ static int cm_init_qp_init_attr(struct cm_id_private *cm_id_priv,
>  		qp_attr->qp_access_flags = IB_ACCESS_REMOTE_WRITE;
>  		if (cm_id_priv->responder_resources)
>  			qp_attr->qp_access_flags |= IB_ACCESS_REMOTE_READ |
> -						    IB_ACCESS_REMOTE_ATOMIC;
> +						    IB_ACCESS_REMOTE_ATOMIC |
> +						    IB_ACCESS_FLUSHABLE;

What is the point of this? Nothing checks IB_ACCESS_FLUSHABLE ?

Do flush ops require a responder resource?

Why should CM set it unconditionally?

Explain in the commit message

Jason