linux-kernel - Re: [PATCH for-next 9/9] RDMA/hns: Fix different dgids mapping to the same dip

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Message-ID: <20240910131205.GB4026@unreal>
Date: Tue, 10 Sep 2024 16:12:05 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Junxian Huang <huangjunxian6@...ilicon.com>
Cc: jgg@...pe.ca, linux-rdma@...r.kernel.org, linuxarm@...wei.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH for-next 9/9] RDMA/hns: Fix different dgids mapping to
 the same dip_idx

On Fri, Sep 06, 2024 at 05:34:44PM +0800, Junxian Huang wrote:
> From: Feng Fang <fangfeng4@...wei.com>
> 
> DIP algorithm requires a one-to-one mapping between dgid and dip_idx.
> Currently a queue 'spare_idx' is used to store QPN of QPs that use
> DIP algorithm. For a new dgid, use a QPN from spare_idx as dip_idx.
> This method lacks a mechanism for deduplicating QPN, which may result
> in different dgids sharing the same dip_idx and break the one-to-one
> mapping requirement.
> 
> This patch replaces spare_idx with two new bitmaps: qpn_bitmap to record
> QPN that is not being used as dip_idx, and dip_idx_map to record QPN
> that is being used. Besides, introduce a reference count of a dip_idx
> to indicate the number of QPs that using this dip_idx. When creating
> a DIP QP, if it has a new dgid, set the corresponding bit in dip_idx_map,
> otherwise add 1 to the reference count of the reused dip_idx and set bit
> in qpn_bitmap. When destroying a DIP QP, decrement the reference count
> by 1. If it becomes 0, set bit in qpn_bitmap and clear bit in dip_idx_map.
> 
> Fixes: eb653eda1e91 ("RDMA/hns: Bugfix for incorrect association between dip_idx and dgid")
> Fixes: f91696f2f053 ("RDMA/hns: Support congestion control type selection according to the FW")
> Signed-off-by: Feng Fang <fangfeng4@...wei.com>
> Signed-off-by: Junxian Huang <huangjunxian6@...ilicon.com>
> ---
>  drivers/infiniband/hw/hns/hns_roce_device.h |  6 +--
>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c  | 58 ++++++++++++++++++---
>  drivers/infiniband/hw/hns/hns_roce_hw_v2.h  |  1 +
>  drivers/infiniband/hw/hns/hns_roce_qp.c     | 16 ++++--
>  4 files changed, 67 insertions(+), 14 deletions(-)

It is strange implementation, double bitmap and refcount looks like
open-coding of some basic coding patterns. Let's wait with applying it
for now.

Thanks