From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-eopbgr710058.outbound.protection.outlook.com ([40.107.71.58]:14064 "EHLO NAM05-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S935092AbeF1Jog (ORCPT ); Thu, 28 Jun 2018 05:44:36 -0400 Message-ID: <5B34ADF7.6040508@amd.com> Date: Thu, 28 Jun 2018 17:44:23 +0800 From: "Zhang, Jerry (Junwei)" MIME-Version: 1.0 To: =?UTF-8?B?Q2hyaXN0aWFuIEvDtm5pZw==?= , , , , , , Subject: Re: [PATCH 1/4] dma-buf: add dma_buf_(un)map_attachment_locked variants v2 References: <20180622141103.1787-1-christian.koenig@amd.com> <20180622141103.1787-2-christian.koenig@amd.com> In-Reply-To: <20180622141103.1787-2-christian.koenig@amd.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: On 06/22/2018 10:11 PM, Christian König wrote: > Add function variants which can be called with the reservation lock > already held. > > v2: reordered, add lockdep asserts, fix kerneldoc > > Signed-off-by: Christian König > --- > drivers/dma-buf/dma-buf.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/dma-buf.h | 5 +++++ > 2 files changed, 62 insertions(+) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 852a3928ee71..dc94e76e2e2a 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -606,6 +606,40 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) > } > EXPORT_SYMBOL_GPL(dma_buf_detach); > > +/** > + * dma_buf_map_attachment_locked - Maps the buffer into _device_ address space > + * with the reservation lock held. Is a wrapper for map_dma_buf() of the > + * > + * Returns the scatterlist table of the attachment; > + * dma_buf_ops. > + * @attach: [in] attachment whose scatterlist is to be returned > + * @direction: [in] direction of DMA transfer > + * > + * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR > + * on error. May return -EINTR if it is interrupted by a signal. > + * > + * A mapping must be unmapped by using dma_buf_unmap_attachment_locked(). Note > + * that the underlying backing storage is pinned for as long as a mapping > + * exists, therefore users/importers should not hold onto a mapping for undue > + * amounts of time. > + */ > +struct sg_table * > +dma_buf_map_attachment_locked(struct dma_buf_attachment *attach, > + enum dma_data_direction direction) > +{ > + struct sg_table *sg_table; > + Perhaps better to add some error check, like dma_buf_map_attachment() WARN_ON(!attach || !attach->dmabuf) Apart from that, it's Reviewed-by: Junwei Zhang Jerry > + might_sleep(); > + reservation_object_assert_held(attach->dmabuf->resv); > + > + sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); > + if (!sg_table) > + sg_table = ERR_PTR(-ENOMEM); > + > + return sg_table; > +} > +EXPORT_SYMBOL_GPL(dma_buf_map_attachment_locked); > + > /** > * dma_buf_map_attachment - Returns the scatterlist table of the attachment; > * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the > @@ -639,6 +673,29 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, > } > EXPORT_SYMBOL_GPL(dma_buf_map_attachment); > > +/** > + * dma_buf_unmap_attachment_locked - unmaps the buffer with reservation lock > + * held, should deallocate the associated scatterlist. Is a wrapper for > + * unmap_dma_buf() of dma_buf_ops. > + * @attach: [in] attachment to unmap buffer from > + * @sg_table: [in] scatterlist info of the buffer to unmap > + * @direction: [in] direction of DMA transfer > + * > + * This unmaps a DMA mapping for @attached obtained by > + * dma_buf_map_attachment_locked(). > + */ > +void dma_buf_unmap_attachment_locked(struct dma_buf_attachment *attach, > + struct sg_table *sg_table, > + enum dma_data_direction direction) > +{ > + might_sleep(); > + reservation_object_assert_held(attach->dmabuf->resv); > + > + attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, > + direction); > +} > +EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment_locked); > + > /** > * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might > * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index 991787a03199..a25e754ae2f7 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -384,8 +384,13 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags); > struct dma_buf *dma_buf_get(int fd); > void dma_buf_put(struct dma_buf *dmabuf); > > +struct sg_table *dma_buf_map_attachment_locked(struct dma_buf_attachment *, > + enum dma_data_direction); > struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, > enum dma_data_direction); > +void dma_buf_unmap_attachment_locked(struct dma_buf_attachment *, > + struct sg_table *, > + enum dma_data_direction); > void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, > enum dma_data_direction); > int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, >