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[174.3.196.123]) by smtp.gmail.com with ESMTPSA id z9sm8093420pfd.99.2019.01.30.13.23.47 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 30 Jan 2019 13:23:47 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1goxKk-0006QL-O8; Wed, 30 Jan 2019 14:23:46 -0700 Date: Wed, 30 Jan 2019 14:23:46 -0700 From: Jason Gunthorpe To: Joel Nider Cc: Doug Ledford , Leon Romanovsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rdma@vger.kernel.org, linux-rdma-owner@vger.kernel.org, Mike Rapoport Subject: Re: [PATCH 5/5] RDMA/uverbs: add UVERBS_METHOD_REG_REMOTE_MR Message-ID: <20190130212346.GD17066@ziepe.ca> References: <1548768386-28289-1-git-send-email-joeln@il.ibm.com> <1548768386-28289-6-git-send-email-joeln@il.ibm.com> <20190129170406.GD10094@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 30, 2019 at 10:34:02AM +0200, Joel Nider wrote: > linux-rdma-owner@vger.kernel.org wrote on 01/29/2019 07:04:06 PM: > > > On Tue, Jan 29, 2019 at 03:26:26PM +0200, Joel Nider wrote: > > > Add a new handler for new uverb reg_remote_mr. The purpose is to > register > > > a memory region in a different address space (i.e. process) than the > > > caller. > > > > > > The main use case which motivated this change is post-copy container > > > migration. When a migration manager (i.e. CRIU) starts a migration, it > > > must have an open connection for handling any page faults that occur > > > in the container after restoration on the target machine. Even though > > > CRIU establishes and maintains the connection, ultimately the memory > > > is copied from the container being migrated (i.e. a remote address > > > space). This container must remain passive -- meaning it cannot have > > > any knowledge of the RDMA connection; therefore the migration manager > > > must have the ability to register a remote memory region. This remote > > > memory region will serve as the source for any memory pages that must > > > be copied (on-demand or otherwise) during the migration. > > > > > > Signed-off-by: Joel Nider > > > drivers/infiniband/core/uverbs_std_types_mr.c | 129 > +++++++++++++++++++++++++- > > > include/rdma/ib_verbs.h | 8 ++ > > > include/uapi/rdma/ib_user_ioctl_cmds.h | 13 +++ > > > 3 files changed, 149 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/infiniband/core/uverbs_std_types_mr.c b/drivers/ > > infiniband/core/uverbs_std_types_mr.c > > > index 4d4be0c..bf7b4b2 100644 > > > +++ b/drivers/infiniband/core/uverbs_std_types_mr.c > > > @@ -150,6 +150,99 @@ static int > UVERBS_HANDLER(UVERBS_METHOD_DM_MR_REG)( > > > return ret; > > > } > > > > > > +static int UVERBS_HANDLER(UVERBS_METHOD_REG_REMOTE_MR)( > > > + struct uverbs_attr_bundle *attrs) > > > +{ > > > > I think this should just be REG_MR with an optional remote PID > > argument > > Maybe I missed something. Isn't REG_MR only implemented as a write() > command? In our earlier conversation you told me all new commands must be > implemented as ioctl() commands. Yes - but we are also converting old write() commands into ioctl() when they need new functionality. So in this case it should convert reg_mr to ioctl() then add an optional report PID argument > > > > DECLARE_UVERBS_NAMED_OBJECT( > > > UVERBS_OBJECT_MR, > > > UVERBS_TYPE_ALLOC_IDR(uverbs_free_mr), > > > &UVERBS_METHOD(UVERBS_METHOD_DM_MR_REG), > > > &UVERBS_METHOD(UVERBS_METHOD_MR_DESTROY), > > > - &UVERBS_METHOD(UVERBS_METHOD_ADVISE_MR)); > > > + &UVERBS_METHOD(UVERBS_METHOD_ADVISE_MR), > > > + &UVERBS_METHOD(UVERBS_METHOD_REG_REMOTE_MR), > > > +); > > > > I'm kind of surprised this compiles with the trailing comma? > Personally, I think it is nicer with the trailing comma. Of course > syntactically it makes no sense, but when adding a new entry, you don't > have to touch the previous line, which makes the diff cleaner. If this is > against standard practices I will remove the comma. Well, it is just that this is a macro call, and you usually can't have a trailing comma in a function-macro call, at least I thought this was the case.. Without some study I'm not sure what it expands to, or if that expansion is even OK.. Jason