Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 5 Aug 2021 09:23:11 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Leon Romanovsky <leon@kernel.org>
Cc:     YueHaibing <yuehaibing@huawei.com>, liangwenpeng@huawei.com,
        liweihang@huawei.com, dledford@redhat.com, chenglang@huawei.com,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -next] RDMA/hns: Fix return in hns_roce_rereg_user_mr()
Message-ID: <20210805122311.GJ543798@ziepe.ca>
References: <20210804125939.20516-1-yuehaibing@huawei.com>
 <YQqb0U43eQUGK641@unreal>
 <f0921aa3-a95d-f7e4-a13b-db15d4a5f259@huawei.com>
 <YQtdswHgMXhC7Mf5@unreal>
 <974d3309-3617-6413-5a8d-c92b1b2f8dfe@huawei.com>
 <YQvEbUp9cE5G535E@unreal>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YQvEbUp9cE5G535E@unreal>
Precedence: bulk

On Thu, Aug 05, 2021 at 01:58:53PM +0300, Leon Romanovsky wrote:

> > IMO, if ibv_rereg_mr failed, the mr is in undefined state, user
> > needs to call ibv_dereg_mr in order to release it, so there no
> > need to recover the original state.
> 
> The thing is that it undefined state in the kernel.  What will be if
> user will change access_flags and try to use that "broken" MR
> anyway? Will you catch it?

rereg is not atomic, if the rereg fails in the middle the mr should be
left in some safe state.

Jason