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Wed, 26 Aug 2020 06:35:44 +0000 (GMT) From: Marek Szyprowski To: dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: Marek Szyprowski , Christoph Hellwig , Robin Murphy , Bartlomiej Zolnierkiewicz , linux-arm-kernel@lists.infradead.org, David Airlie , Daniel Vetter , Matt Porter , Alexandre Bounine Subject: [PATCH v9 29/32] rapidio: fix common struct sg_table related issues Date: Wed, 26 Aug 2020 08:33:13 +0200 Message-Id: <20200826063316.23486-30-m.szyprowski@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200826063316.23486-1-m.szyprowski@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrDKsWRmVeSWpSXmKPExsWy7djPc7oHmdziDWZO0LHoPXeSyeLRqhvM FhtnrGe1+L9tIrPFla/v2SxWrj7KZLFgv7XFlysPmSw2Pb7GanF51xw2i7VH7rJbTD3/ndni 4IcnrA68HmvmrWH02PttAYvHzll32T163rSwemz/9oDV4373cSaPzUvqPW7/e8zsMfnGckaP 3Tcb2Dz6tqxi9Pi8SS6AJ4rLJiU1J7MstUjfLoEr49zHhcwFd0Qr2r/sYGtg/CHYxcjJISFg InFj1nPmLkYuDiGBFYwSL0/8Y4RwvjBKPJz/mQXC+cwo8b/rCjtMy+eVM6BaljNKXFt+mh2u 5cGfr2BVbAKGEl1vu9hAbBGBVkaJE708IDazwDsmiSOftUBsYQEfiRl7rzOC2CwCqhJvp30F q+cVsJPYNeEYG8Q2eYnVGw4wg9icQPHj3f1sIMskBM6xS+w70MYEUeQisffQf6gGYYlXx7dA nSoj8X/nfCaIhmagh86tZYdwehglLjfNYISospa4c+4XUDcH0HmaEut36UOEHSUW3gBp5gCy +SRuvBWEeIBPYtK26cwQYV6JjjYhiGo1iVnH18GtPXjhEjOE7SHRPvE6EySAJjJKXHndwzaB UX4WwrIFjIyrGMVTS4tz01OLDfNSy/WKE3OLS/PS9ZLzczcxAtPU6X/HP+1g/Hop6RCjAAej Eg/vAjbXeCHWxLLiytxDjBIczEoivE5nT8cJ8aYkVlalFuXHF5XmpBYfYpTmYFES5zVe9DJW SCA9sSQ1OzW1ILUIJsvEwSnVwOi6/5TRnxlG6xMi6/hW6+7La3jWu9n5kFk893O9E0/n5h2z 71GO/as6PU3Mvk/7+6dZ80wsWKSUZ7e/nLtv+SITgSuvzcw+V0ywmrh9W92kqy5Gn/NPXA89 NOMIn1e88Y1ohi53wUWBr2sqsq9cmTLNzvPfY//AhM2/c6caz1Le89Tk4pqzkppKLMUZiYZa zEXFiQBVLYjGTwMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprLIsWRmVeSWpSXmKPExsVy+t/xe7oHmdziDdZ/F7XoPXeSyeLRqhvM FhtnrGe1+L9tIrPFla/v2SxWrj7KZLFgv7XFlysPmSw2Pb7GanF51xw2i7VH7rJbTD3/ndni 4IcnrA68HmvmrWH02PttAYvHzll32T163rSwemz/9oDV4373cSaPzUvqPW7/e8zsMfnGckaP 3Tcb2Dz6tqxi9Pi8SS6AJ0rPpii/tCRVISO/uMRWKdrQwkjP0NJCz8jEUs/Q2DzWyshUSd/O JiU1J7MstUjfLkEv49zHhcwFd0Qr2r/sYGtg/CHYxcjJISFgIvF55QzmLkYuDiGBpYwSE96t ZYJIyEicnNbACmELS/y51sUGYgsJfGKU6P4aDmKzCRhKdL0FiXNxiAh0MkpM6/7IDuIwC3xj kpi09BZYh7CAj8SMvdcZQWwWAVWJt9O+gsV5Bewkdk04xgaxQV5i9YYDzCA2J1D8eHc/1DZb idNrZzBPYORbwMiwilEktbQ4Nz232EivODG3uDQvXS85P3cTIzBqth37uWUHY9e74EOMAhyM Sjy8C9hc44VYE8uKK3MPMUpwMCuJ8DqdPR0nxJuSWFmVWpQfX1Sak1p8iNEU6KiJzFKiyfnA iM4riTc0NTS3sDQ0NzY3NrNQEuftEDgYIySQnliSmp2aWpBaBNPHxMEp1cDYN/lbUUdep/dj FaGTWZMlzJrm1krxL436zJLa/WRNbKiwln+a5oxivsxank18Nppmhkn3T9w9M1lv0+y3wSIq ToIznoa822efuObxseUbnjBt55+y9mbG8Z5d6jMU1Nau/N0yqzM8zbF1b8dE09tSMXsMVnut bynW034hoNuz8UbAoQoTQSclluKMREMt5qLiRABTDpensAIAAA== X-CMS-MailID: 20200826063545eucas1p22eb2c7a643a299f3e1696b4c5bae0694 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200826063545eucas1p22eb2c7a643a299f3e1696b4c5bae0694 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200826063545eucas1p22eb2c7a643a299f3e1696b4c5bae0694 References: <20200826063316.23486-1-m.szyprowski@samsung.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function returns the number of the created entries in the DMA address space. However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and dma_unmap_sg must be called with the original number of the entries passed to the dma_map_sg(). struct sg_table is a common structure used for describing a non-contiguous memory buffer, used commonly in the DRM and graphics subsystems. It consists of a scatterlist with memory pages and DMA addresses (sgl entry), as well as the number of scatterlist entries: CPU pages (orig_nents entry) and DMA mapped pages (nents entry). It turned out that it was a common mistake to misuse nents and orig_nents entries, calling DMA-mapping functions with a wrong number of entries or ignoring the number of mapped entries returned by the dma_map_sg() function. To avoid such issues, lets use a common dma-mapping wrappers operating directly on the struct sg_table objects and use scatterlist page iterators where possible. This, almost always, hides references to the nents and orig_nents entries, making the code robust, easier to follow and copy/paste safe. Signed-off-by: Marek Szyprowski --- drivers/rapidio/devices/rio_mport_cdev.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c index a30342942e26..89eb3d212652 100644 --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -573,8 +573,7 @@ static void dma_req_free(struct kref *ref) refcount); struct mport_cdev_priv *priv = req->priv; - dma_unmap_sg(req->dmach->device->dev, - req->sgt.sgl, req->sgt.nents, req->dir); + dma_unmap_sgtable(req->dmach->device->dev, &req->sgt, req->dir, 0); sg_free_table(&req->sgt); if (req->page_list) { unpin_user_pages(req->page_list, req->nr_pages); @@ -814,7 +813,6 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode, struct mport_dev *md = priv->md; struct dma_chan *chan; int ret; - int nents; if (xfer->length == 0) return -EINVAL; @@ -930,15 +928,14 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode, xfer->offset, xfer->length); } - nents = dma_map_sg(chan->device->dev, - req->sgt.sgl, req->sgt.nents, dir); - if (nents == 0) { + ret = dma_map_sgtable(chan->device->dev, &req->sgt, dir, 0); + if (ret) { rmcd_error("Failed to map SG list"); ret = -EFAULT; goto err_pg; } - ret = do_dma_request(req, xfer, sync, nents); + ret = do_dma_request(req, xfer, sync, req->sgt.nents); if (ret >= 0) { if (sync == RIO_TRANSFER_ASYNC) -- 2.17.1