linux-kernel - Re: [PATCH -next] RDMA/hns: Fix return in hns_roce_rereg_user

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Message-ID: <20210805122311.GJ543798@ziepe.ca>
Date:   Thu, 5 Aug 2021 09:23:11 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     YueHaibing <yuehaibing@...wei.com>, liangwenpeng@...wei.com,
        liweihang@...wei.com, dledford@...hat.com, chenglang@...wei.com,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] RDMA/hns: Fix return in hns_roce_rereg_user_mr()

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