| Message ID | 20200826063316.23486-4-m.szyprowski@samsung.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | DRM: fix struct sg_table nents vs. orig_nents misuse | expand |
On 2020-08-26 07:32, 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. > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> > --- > drivers/gpu/drm/drm_cache.c | 2 +- > drivers/gpu/drm/drm_gem_shmem_helper.c | 14 +++++++++----- > drivers/gpu/drm/drm_prime.c | 11 ++++++----- > 3 files changed, 16 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c > index 03e01b000f7a..0fe3c496002a 100644 > --- a/drivers/gpu/drm/drm_cache.c > +++ b/drivers/gpu/drm/drm_cache.c > @@ -127,7 +127,7 @@ drm_clflush_sg(struct sg_table *st) > struct sg_page_iter sg_iter; > > mb(); /*CLFLUSH is ordered only by using memory barriers*/ > - for_each_sg_page(st->sgl, &sg_iter, st->nents, 0) > + for_each_sgtable_page(st, &sg_iter, 0) > drm_clflush_page(sg_page_iter_page(&sg_iter)); > mb(); /*Make sure that all cache line entry is flushed*/ > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index 4b7cfbac4daa..47d8211221f2 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -126,8 +126,8 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj) > drm_prime_gem_destroy(obj, shmem->sgt); > } else { > if (shmem->sgt) { > - dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl, > - shmem->sgt->nents, DMA_BIDIRECTIONAL); > + dma_unmap_sgtable(obj->dev->dev, shmem->sgt, > + DMA_BIDIRECTIONAL, 0); > sg_free_table(shmem->sgt); > kfree(shmem->sgt); > } > @@ -424,8 +424,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_object *obj) > > WARN_ON(!drm_gem_shmem_is_purgeable(shmem)); > > - dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl, > - shmem->sgt->nents, DMA_BIDIRECTIONAL); > + dma_unmap_sgtable(obj->dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0); > sg_free_table(shmem->sgt); > kfree(shmem->sgt); > shmem->sgt = NULL; > @@ -697,12 +696,17 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj) > goto err_put_pages; > } > /* Map the pages for use by the h/w. */ > - dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL); > + ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0); > + if (ret) > + goto err_free_sgt; > > shmem->sgt = sgt; > > return sgt; > > +err_free_sgt: > + sg_free_table(sgt); > + kfree(sgt); Should this be a separate patch to add the missing error handling to the existing code first? Otherwise the rest of the mechanical conversion looks straightforward enough, and I'm not the separation-of-concerns police (for this subsystem, at least), so either way, Reviewed-by: Robin Murphy <robin.murphy@arm.com> > err_put_pages: > drm_gem_shmem_put_pages(shmem); > return ERR_PTR(ret); > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > index 5d181bf60a44..c45b0cc6e31d 100644 > --- a/drivers/gpu/drm/drm_prime.c > +++ b/drivers/gpu/drm/drm_prime.c > @@ -617,6 +617,7 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach, > { > struct drm_gem_object *obj = attach->dmabuf->priv; > struct sg_table *sgt; > + int ret; > > if (WARN_ON(dir == DMA_NONE)) > return ERR_PTR(-EINVAL); > @@ -626,11 +627,12 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach, > else > sgt = obj->dev->driver->gem_prime_get_sg_table(obj); > > - if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir, > - DMA_ATTR_SKIP_CPU_SYNC)) { > + ret = dma_map_sgtable(attach->dev, sgt, dir, > + DMA_ATTR_SKIP_CPU_SYNC); > + if (ret) { > sg_free_table(sgt); > kfree(sgt); > - sgt = ERR_PTR(-ENOMEM); > + sgt = ERR_PTR(ret); > } > > return sgt; > @@ -652,8 +654,7 @@ void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach, > if (!sgt) > return; > > - dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir, > - DMA_ATTR_SKIP_CPU_SYNC); > + dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC); > sg_free_table(sgt); > kfree(sgt); > } > _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c index 03e01b000f7a..0fe3c496002a 100644 --- a/drivers/gpu/drm/drm_cache.c +++ b/drivers/gpu/drm/drm_cache.c @@ -127,7 +127,7 @@ drm_clflush_sg(struct sg_table *st) struct sg_page_iter sg_iter; mb(); /*CLFLUSH is ordered only by using memory barriers*/ - for_each_sg_page(st->sgl, &sg_iter, st->nents, 0) + for_each_sgtable_page(st, &sg_iter, 0) drm_clflush_page(sg_page_iter_page(&sg_iter)); mb(); /*Make sure that all cache line entry is flushed*/ diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 4b7cfbac4daa..47d8211221f2 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -126,8 +126,8 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj) drm_prime_gem_destroy(obj, shmem->sgt); } else { if (shmem->sgt) { - dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl, - shmem->sgt->nents, DMA_BIDIRECTIONAL); + dma_unmap_sgtable(obj->dev->dev, shmem->sgt, + DMA_BIDIRECTIONAL, 0); sg_free_table(shmem->sgt); kfree(shmem->sgt); } @@ -424,8 +424,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_object *obj) WARN_ON(!drm_gem_shmem_is_purgeable(shmem)); - dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl, - shmem->sgt->nents, DMA_BIDIRECTIONAL); + dma_unmap_sgtable(obj->dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0); sg_free_table(shmem->sgt); kfree(shmem->sgt); shmem->sgt = NULL; @@ -697,12 +696,17 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj) goto err_put_pages; } /* Map the pages for use by the h/w. */ - dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL); + ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0); + if (ret) + goto err_free_sgt; shmem->sgt = sgt; return sgt; +err_free_sgt: + sg_free_table(sgt); + kfree(sgt); err_put_pages: drm_gem_shmem_put_pages(shmem); return ERR_PTR(ret); diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 5d181bf60a44..c45b0cc6e31d 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -617,6 +617,7 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach, { struct drm_gem_object *obj = attach->dmabuf->priv; struct sg_table *sgt; + int ret; if (WARN_ON(dir == DMA_NONE)) return ERR_PTR(-EINVAL); @@ -626,11 +627,12 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach, else sgt = obj->dev->driver->gem_prime_get_sg_table(obj); - if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir, - DMA_ATTR_SKIP_CPU_SYNC)) { + ret = dma_map_sgtable(attach->dev, sgt, dir, + DMA_ATTR_SKIP_CPU_SYNC); + if (ret) { sg_free_table(sgt); kfree(sgt); - sgt = ERR_PTR(-ENOMEM); + sgt = ERR_PTR(ret); } return sgt; @@ -652,8 +654,7 @@ void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach, if (!sgt) return; - dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir, - DMA_ATTR_SKIP_CPU_SYNC); + dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC); sg_free_table(sgt); kfree(sgt); }
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> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> --- drivers/gpu/drm/drm_cache.c | 2 +- drivers/gpu/drm/drm_gem_shmem_helper.c | 14 +++++++++----- drivers/gpu/drm/drm_prime.c | 11 ++++++----- 3 files changed, 16 insertions(+), 11 deletions(-) -- 2.17.1 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel