Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034128AbcJ1Rfo (ORCPT ); Fri, 28 Oct 2016 13:35:44 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:25187 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941477AbcJ1Rfm (ORCPT ); Fri, 28 Oct 2016 13:35:42 -0400 Date: Fri, 28 Oct 2016 13:35:11 -0400 From: Konrad Rzeszutek Wilk To: Alexander Duyck Cc: netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, brouer@redhat.com, davem@davemloft.net Subject: Re: [net-next PATCH 02/27] swiotlb-xen: Enforce return of DMA_ERROR_CODE in mapping function Message-ID: <20161028173511.GF5112@char.us.oracle.com> References: <20161025153220.4815.61239.stgit@ahduyck-blue-test.jf.intel.com> <20161025153658.4815.84254.stgit@ahduyck-blue-test.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161025153658.4815.84254.stgit@ahduyck-blue-test.jf.intel.com> User-Agent: Mutt/1.6.2 (2016-07-01) X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3970 Lines: 103 On Tue, Oct 25, 2016 at 11:36:58AM -0400, Alexander Duyck wrote: > The mapping function should always return DMA_ERROR_CODE when a mapping has > failed as this is what the DMA API expects when a DMA error has occurred. > The current function for mapping a page in Xen was returning either > DMA_ERROR_CODE or 0 depending on where it failed. > > On x86 DMA_ERROR_CODE is 0, but on other architectures such as ARM it is > ~0. We need to make sure we return the same error value if either the > mapping failed or the device is not capable of accessing the mapping. > > If we are returning DMA_ERROR_CODE as our error value we can drop the > function for checking the error code as the default is to compare the > return value against DMA_ERROR_CODE if no function is defined. > > Cc: Konrad Rzeszutek Wilk I am pretty sure I gave an Ack. Any particular reason from dropping it (if so, please add a comment under the --- of the reason). Thanks. > Signed-off-by: Alexander Duyck > --- > arch/arm/xen/mm.c | 1 - > arch/x86/xen/pci-swiotlb-xen.c | 1 - > drivers/xen/swiotlb-xen.c | 18 ++++++------------ > include/xen/swiotlb-xen.h | 3 --- > 4 files changed, 6 insertions(+), 17 deletions(-) > > diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c > index d062f08..bd62d94 100644 > --- a/arch/arm/xen/mm.c > +++ b/arch/arm/xen/mm.c > @@ -186,7 +186,6 @@ void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order) > EXPORT_SYMBOL(xen_dma_ops); > > static struct dma_map_ops xen_swiotlb_dma_ops = { > - .mapping_error = xen_swiotlb_dma_mapping_error, > .alloc = xen_swiotlb_alloc_coherent, > .free = xen_swiotlb_free_coherent, > .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu, > diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c > index 0e98e5d..a9fafb5 100644 > --- a/arch/x86/xen/pci-swiotlb-xen.c > +++ b/arch/x86/xen/pci-swiotlb-xen.c > @@ -19,7 +19,6 @@ > int xen_swiotlb __read_mostly; > > static struct dma_map_ops xen_swiotlb_dma_ops = { > - .mapping_error = xen_swiotlb_dma_mapping_error, > .alloc = xen_swiotlb_alloc_coherent, > .free = xen_swiotlb_free_coherent, > .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu, > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c > index 87e6035..b8014bf 100644 > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -416,11 +416,12 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, > /* > * Ensure that the address returned is DMA'ble > */ > - if (!dma_capable(dev, dev_addr, size)) { > - swiotlb_tbl_unmap_single(dev, map, size, dir); > - dev_addr = 0; > - } > - return dev_addr; > + if (dma_capable(dev, dev_addr, size)) > + return dev_addr; > + > + swiotlb_tbl_unmap_single(dev, map, size, dir); > + > + return DMA_ERROR_CODE; > } > EXPORT_SYMBOL_GPL(xen_swiotlb_map_page); > > @@ -648,13 +649,6 @@ void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, > } > EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device); > > -int > -xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr) > -{ > - return !dma_addr; > -} > -EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mapping_error); > - > /* > * Return whether the given device DMA address mask can be supported > * properly. For example, if your device can only drive the low 24-bits > diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h > index 7c35e27..a0083be 100644 > --- a/include/xen/swiotlb-xen.h > +++ b/include/xen/swiotlb-xen.h > @@ -51,9 +51,6 @@ extern void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, > int nelems, enum dma_data_direction dir); > > extern int > -xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr); > - > -extern int > xen_swiotlb_dma_supported(struct device *hwdev, u64 mask); > > extern int >