Em Sat, 21 Dec 2013 07:42:17 -0500 Rob Clark <robdclark at gmail.com> escreveu:
> On Fri, Dec 20, 2013 at 7:43 PM, Colin Cross <ccross at android.com> wrote: > > dma_buf_map_attachment and dma_buf_vmap can return NULL or > > ERR_PTR on a error. This encourages a common buggy pattern in > > callers: > > sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL); > > if (IS_ERR_OR_NULL(sgt)) > > return PTR_ERR(sgt); > > > > This causes the caller to return 0 on an error. IS_ERR_OR_NULL > > is almost always a sign of poorly-defined error handling. > > > > This patch converts dma_buf_map_attachment to always return > > ERR_PTR, and fixes the callers that incorrectly handled NULL. > > There are a few more callers that were not checking for NULL > > at all, which would have dereferenced a NULL pointer later. > > There are also a few more callers that correctly handled NULL > > and ERR_PTR differently, I left those alone but they could also > > be modified to delete the NULL check. > > > > This patch also converts dma_buf_vmap to always return NULL. > > All the callers to dma_buf_vmap only check for NULL, and would > > have dereferenced an ERR_PTR and panic'd if one was ever > > returned. This is not consistent with the rest of the dma buf > > APIs, but matches the expectations of all of the callers. > > > > Signed-off-by: Colin Cross <ccross at android.com> > > --- > > drivers/base/dma-buf.c | 18 +++++++++++------- > > drivers/gpu/drm/drm_prime.c | 2 +- > > drivers/gpu/drm/exynos/exynos_drm_dmabuf.c | 2 +- > > drivers/media/v4l2-core/videobuf2-dma-contig.c | 2 +- > > 4 files changed, 14 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c > > index 1e16cbd61da2..cfe1d8bc7bb8 100644 > > --- a/drivers/base/dma-buf.c > > +++ b/drivers/base/dma-buf.c > > @@ -251,9 +251,8 @@ EXPORT_SYMBOL_GPL(dma_buf_put); > > * @dmabuf: [in] buffer to attach device to. > > * @dev: [in] device to be attached. > > * > > - * Returns struct dma_buf_attachment * for this attachment; may return > > negative > > - * error codes. > > - * > > + * Returns struct dma_buf_attachment * for this attachment; returns > > ERR_PTR on > > + * error. > > */ > > struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, > > struct device *dev) > > @@ -319,9 +318,8 @@ EXPORT_SYMBOL_GPL(dma_buf_detach); > > * @attach: [in] attachment whose scatterlist is to be returned > > * @direction: [in] direction of DMA transfer > > * > > - * Returns sg_table containing the scatterlist to be returned; may return > > NULL > > - * or ERR_PTR. > > - * > > + * Returns sg_table containing the scatterlist to be returned; returns > > ERR_PTR > > + * on error. > > */ > > struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, > > enum dma_data_direction direction) > > @@ -334,6 +332,8 @@ struct sg_table *dma_buf_map_attachment(struct > > dma_buf_attachment *attach, > > return ERR_PTR(-EINVAL); > > > > sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); > > + if (!sg_table) > > + sg_table = ERR_PTR(-ENOMEM); > > > > return sg_table; > > } > > @@ -544,6 +544,8 @@ EXPORT_SYMBOL_GPL(dma_buf_mmap); > > * These calls are optional in drivers. The intended use for them > > * is for mapping objects linear in kernel space for high use objects. > > * Please attempt to use kmap/kunmap before thinking about these > > interfaces. > > + * > > + * Returns NULL on error. > > */ > > void *dma_buf_vmap(struct dma_buf *dmabuf) > > { > > @@ -566,7 +568,9 @@ void *dma_buf_vmap(struct dma_buf *dmabuf) > > BUG_ON(dmabuf->vmap_ptr); > > > > ptr = dmabuf->ops->vmap(dmabuf); > > - if (IS_ERR_OR_NULL(ptr)) > > + if (WARN_ON_ONCE(IS_ERR(ptr))) > > since vmap is optional, the WARN_ON might be a bit strong.. although > it would be a bit strange for an exporter to supply a vmap fxn which > always returned NULL, not sure about that. Just thought I'd mention > it in case anyone else had an opinion about that. > > But either way: > > Reviewed-by: Rob Clark <robdclark at gmail.com> IMHO, a WARN_ON_ONCE() here (or some other error report printk) seems ok, as, if this function is called, the caller would be expecting it to not fail. Either way: Reviewed-by: Mauro Carvalho Chehab <m.chehab at samsung.com> > > > > + ptr = NULL; > > + if (!ptr) > > goto out_unlock; > > > > dmabuf->vmap_ptr = ptr; > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > > index 56805c39c906..bb516fdd195d 100644 > > --- a/drivers/gpu/drm/drm_prime.c > > +++ b/drivers/gpu/drm/drm_prime.c > > @@ -471,7 +471,7 @@ struct drm_gem_object *drm_gem_prime_import(struct > > drm_device *dev, > > get_dma_buf(dma_buf); > > > > sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL); > > - if (IS_ERR_OR_NULL(sgt)) { > > + if (IS_ERR(sgt)) { > > ret = PTR_ERR(sgt); > > goto fail_detach; > > } > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c > > b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c > > index 59827cc5e770..c786cd4f457b 100644 > > --- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c > > +++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c > > @@ -224,7 +224,7 @@ struct drm_gem_object > > *exynos_dmabuf_prime_import(struct drm_device *drm_dev, > > get_dma_buf(dma_buf); > > > > sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL); > > - if (IS_ERR_OR_NULL(sgt)) { > > + if (IS_ERR(sgt)) { > > ret = PTR_ERR(sgt); > > goto err_buf_detach; > > } > > diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c > > b/drivers/media/v4l2-core/videobuf2-dma-contig.c > > index 33d3871d1e13..880be0782dd9 100644 > > --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c > > +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c > > @@ -719,7 +719,7 @@ static int vb2_dc_map_dmabuf(void *mem_priv) > > > > /* get the associated scatterlist for this buffer */ > > sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir); > > - if (IS_ERR_OR_NULL(sgt)) { > > + if (IS_ERR(sgt)) { > > pr_err("Error getting dmabuf scatterlist\n"); > > return -EINVAL; > > } > > -- > > 1.8.5.1 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo at vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Cheers, Mauro