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dma-buf: avoid using IS_ERR_OR_NULL
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@android.com> Reviewed-by: Rob Clark <robdclark@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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parent
38dbfb59d1
commit
fee0c54e28
4 changed files with 14 additions and 10 deletions
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@ -251,9 +251,8 @@ EXPORT_SYMBOL_GPL(dma_buf_put);
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* @dmabuf: [in] buffer to attach device to.
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* @dev: [in] device to be attached.
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*
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* Returns struct dma_buf_attachment * for this attachment; may return negative
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* error codes.
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*
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* Returns struct dma_buf_attachment * for this attachment; returns ERR_PTR on
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* error.
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*/
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struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
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struct device *dev)
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@ -319,9 +318,8 @@ EXPORT_SYMBOL_GPL(dma_buf_detach);
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* @attach: [in] attachment whose scatterlist is to be returned
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* @direction: [in] direction of DMA transfer
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*
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* Returns sg_table containing the scatterlist to be returned; may return NULL
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* or ERR_PTR.
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*
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* Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
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* on error.
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*/
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struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
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enum dma_data_direction direction)
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@ -334,6 +332,8 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
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return ERR_PTR(-EINVAL);
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sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
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if (!sg_table)
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sg_table = ERR_PTR(-ENOMEM);
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return sg_table;
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}
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@ -544,6 +544,8 @@ EXPORT_SYMBOL_GPL(dma_buf_mmap);
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* These calls are optional in drivers. The intended use for them
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* is for mapping objects linear in kernel space for high use objects.
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* Please attempt to use kmap/kunmap before thinking about these interfaces.
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*
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* Returns NULL on error.
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*/
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void *dma_buf_vmap(struct dma_buf *dmabuf)
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{
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@ -566,7 +568,9 @@ void *dma_buf_vmap(struct dma_buf *dmabuf)
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BUG_ON(dmabuf->vmap_ptr);
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ptr = dmabuf->ops->vmap(dmabuf);
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if (IS_ERR_OR_NULL(ptr))
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if (WARN_ON_ONCE(IS_ERR(ptr)))
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ptr = NULL;
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if (!ptr)
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goto out_unlock;
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dmabuf->vmap_ptr = ptr;
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@ -471,7 +471,7 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
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get_dma_buf(dma_buf);
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sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
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if (IS_ERR_OR_NULL(sgt)) {
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if (IS_ERR(sgt)) {
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ret = PTR_ERR(sgt);
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goto fail_detach;
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}
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@ -224,7 +224,7 @@ struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev,
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get_dma_buf(dma_buf);
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sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
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if (IS_ERR_OR_NULL(sgt)) {
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if (IS_ERR(sgt)) {
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ret = PTR_ERR(sgt);
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goto err_buf_detach;
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}
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@ -719,7 +719,7 @@ static int vb2_dc_map_dmabuf(void *mem_priv)
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/* get the associated scatterlist for this buffer */
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sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
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if (IS_ERR_OR_NULL(sgt)) {
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if (IS_ERR(sgt)) {
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pr_err("Error getting dmabuf scatterlist\n");
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return -EINVAL;
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}
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