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[142.162.113.180]) by smtp.gmail.com with ESMTPSA id d23sm8410524qkc.127.2019.10.21.08.27.21 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 21 Oct 2019 08:27:21 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1iMZab-0000gq-Eu; Mon, 21 Oct 2019 12:27:21 -0300 Date: Mon, 21 Oct 2019 12:27:21 -0300 From: Jason Gunthorpe To: Bart Van Assche Cc: Leon Romanovsky , Doug Ledford , linux-rdma@vger.kernel.org, Christoph Hellwig , stable@vger.kernel.org Subject: Re: [PATCH 1/4] RDMA/core: Fix ib_dma_max_seg_size() Message-ID: <20191021152721.GE25178@ziepe.ca> References: <20191021021030.1037-1-bvanassche@acm.org> <20191021021030.1037-2-bvanassche@acm.org> <20191021140917.GB25178@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-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Mon, Oct 21, 2019 at 08:03:32AM -0700, Bart Van Assche wrote: > On 10/21/19 7:09 AM, Jason Gunthorpe wrote: > > On Sun, Oct 20, 2019 at 07:10:27PM -0700, Bart Van Assche wrote: > > > diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h > > > index 6a47ba85c54c..e6c167d03aae 100644 > > > +++ b/include/rdma/ib_verbs.h > > > @@ -4043,9 +4043,7 @@ static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev, > > > */ > > > static inline unsigned int ib_dma_max_seg_size(struct ib_device *dev) > > > { > > > - struct device_dma_parameters *p = dev->dma_device->dma_parms; > > > - > > > - return p ? p->max_segment_size : UINT_MAX; > > > + return dma_get_max_seg_size(dev->dma_device); > > > } > > > > Should we get rid of this wrapper? > > Hi Jason, > > In general I agree that getting rid of single line inline functions is good. > In this case however I'd like to keep the wrapper such that RDMA ULP code > does not have to deal with the choice between dev->dma_device and &dev->dev. > From struct ib_device: > /* Do not access @dma_device directly from ULP nor from HW drivers. */ > struct device *dma_device; Do you think it is a mistake we have dma_device at all? Can the modern dma framework let us make the 'struct ib_device' into a full dma_device that is still connected to some PCI device? Jason