| Message ID | 20200826063316.23486-25-m.szyprowski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v9,01/32] drm: prime: add common helper to check scatterlist contiguity | expand |
On 2020-08-26 07:33, Marek Szyprowski wrote: > 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. Reviewed-by: Robin Murphy <robin.murphy@arm.com> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > --- > drivers/gpu/host1x/job.c | 22 ++++++++-------------- > 1 file changed, 8 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c > index 89b6c14b7392..82d0a60ba3f7 100644 > --- a/drivers/gpu/host1x/job.c > +++ b/drivers/gpu/host1x/job.c > @@ -170,11 +170,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > goto unpin; > } > > - err = dma_map_sg(dev, sgt->sgl, sgt->nents, dir); > - if (!err) { > - err = -ENOMEM; > + err = dma_map_sgtable(dev, sgt, dir, 0); > + if (err) > goto unpin; > - } > > job->unpins[job->num_unpins].dev = dev; > job->unpins[job->num_unpins].dir = dir; > @@ -228,7 +226,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > } > > if (host->domain) { > - for_each_sg(sgt->sgl, sg, sgt->nents, j) > + for_each_sgtable_sg(sgt, sg, j) > gather_size += sg->length; > gather_size = iova_align(&host->iova, gather_size); > > @@ -240,9 +238,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > goto put; > } > > - err = iommu_map_sg(host->domain, > + err = iommu_map_sgtable(host->domain, > iova_dma_addr(&host->iova, alloc), > - sgt->sgl, sgt->nents, IOMMU_READ); > + sgt, IOMMU_READ); > if (err == 0) { > __free_iova(&host->iova, alloc); > err = -EINVAL; > @@ -252,12 +250,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) > job->unpins[job->num_unpins].size = gather_size; > phys_addr = iova_dma_addr(&host->iova, alloc); > } else if (sgt) { > - err = dma_map_sg(host->dev, sgt->sgl, sgt->nents, > - DMA_TO_DEVICE); > - if (!err) { > - err = -ENOMEM; > + err = dma_map_sgtable(host->dev, sgt, DMA_TO_DEVICE, 0); > + if (err) > goto put; > - } > > job->unpins[job->num_unpins].dir = DMA_TO_DEVICE; > job->unpins[job->num_unpins].dev = host->dev; > @@ -660,8 +655,7 @@ void host1x_job_unpin(struct host1x_job *job) > } > > if (unpin->dev && sgt) > - dma_unmap_sg(unpin->dev, sgt->sgl, sgt->nents, > - unpin->dir); > + dma_unmap_sgtable(unpin->dev, sgt, unpin->dir, 0); > > host1x_bo_unpin(dev, unpin->bo, sgt); > host1x_bo_put(unpin->bo); >
diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c index 89b6c14b7392..82d0a60ba3f7 100644 --- a/drivers/gpu/host1x/job.c +++ b/drivers/gpu/host1x/job.c @@ -170,11 +170,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) goto unpin; } - err = dma_map_sg(dev, sgt->sgl, sgt->nents, dir); - if (!err) { - err = -ENOMEM; + err = dma_map_sgtable(dev, sgt, dir, 0); + if (err) goto unpin; - } job->unpins[job->num_unpins].dev = dev; job->unpins[job->num_unpins].dir = dir; @@ -228,7 +226,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) } if (host->domain) { - for_each_sg(sgt->sgl, sg, sgt->nents, j) + for_each_sgtable_sg(sgt, sg, j) gather_size += sg->length; gather_size = iova_align(&host->iova, gather_size); @@ -240,9 +238,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) goto put; } - err = iommu_map_sg(host->domain, + err = iommu_map_sgtable(host->domain, iova_dma_addr(&host->iova, alloc), - sgt->sgl, sgt->nents, IOMMU_READ); + sgt, IOMMU_READ); if (err == 0) { __free_iova(&host->iova, alloc); err = -EINVAL; @@ -252,12 +250,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) job->unpins[job->num_unpins].size = gather_size; phys_addr = iova_dma_addr(&host->iova, alloc); } else if (sgt) { - err = dma_map_sg(host->dev, sgt->sgl, sgt->nents, - DMA_TO_DEVICE); - if (!err) { - err = -ENOMEM; + err = dma_map_sgtable(host->dev, sgt, DMA_TO_DEVICE, 0); + if (err) goto put; - } job->unpins[job->num_unpins].dir = DMA_TO_DEVICE; job->unpins[job->num_unpins].dev = host->dev; @@ -660,8 +655,7 @@ void host1x_job_unpin(struct host1x_job *job) } if (unpin->dev && sgt) - dma_unmap_sg(unpin->dev, sgt->sgl, sgt->nents, - unpin->dir); + dma_unmap_sgtable(unpin->dev, sgt, unpin->dir, 0); host1x_bo_unpin(dev, unpin->bo, sgt); host1x_bo_put(unpin->bo);
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 <m.szyprowski@samsung.com> --- drivers/gpu/host1x/job.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-)