The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the numer of the created entries in the DMA address space. However the subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be called with the original number of the entries passed to dma_map_sg. The sg_table->nents in turn holds the result of the dma_map_sg call as stated in include/linux/scatterlist.h. A common mistake was to ignore a result of the dma_map_sg function and don't use the sg_table->orig_nents at all.
To avoid such issues, lets use common dma-mapping wrappers operating directly on the struct sg_table objects and adjust references to the nents and orig_nents respectively.
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com --- For more information, see '[PATCH v3 00/25] DRM: fix struct sg_table nents vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/5/187 --- 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 a10643a..850115e 100644 --- a/drivers/gpu/host1x/job.c +++ b/drivers/gpu/host1x/job.c @@ -166,11 +166,9 @@ 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); + if (err) goto unpin; - }
job->unpins[job->num_unpins].dev = dev; job->unpins[job->num_unpins].dir = dir; @@ -217,7 +215,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) }
if (!IS_ENABLED(CONFIG_TEGRA_HOST1X_FIREWALL) && host->domain) { - for_each_sg(sgt->sgl, sg, sgt->nents, j) + for_each_sg(sgt->sgl, sg, sgt->orig_nents, j) gather_size += sg->length; gather_size = iova_align(&host->iova, gather_size);
@@ -229,9 +227,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) goto unpin; }
- 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; @@ -241,12 +239,9 @@ 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); + if (err) goto unpin; - }
job->unpins[job->num_unpins].dir = DMA_TO_DEVICE; job->unpins[job->num_unpins].dev = host->dev; @@ -647,8 +642,7 @@ 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);
host1x_bo_unpin(dev, unpin->bo, sgt); host1x_bo_put(unpin->bo);