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author | Colin Cross <ccross@android.com> | 2013-12-20 16:43:50 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-07 14:21:09 -0800 |
commit | fee0c54e28f6ca187add93dfca226a8093cfa931 (patch) | |
tree | d62c8c58d90fda69cf035b36c457a8ce9df945ca /drivers/base/dma-buf.c | |
parent | 38dbfb59d1175ef458d006556061adeaa8751b72 (diff) | |
download | linux-stable-fee0c54e28f6ca187add93dfca226a8093cfa931.tar.gz linux-stable-fee0c54e28f6ca187add93dfca226a8093cfa931.tar.bz2 linux-stable-fee0c54e28f6ca187add93dfca226a8093cfa931.zip |
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>
Diffstat (limited to 'drivers/base/dma-buf.c')
-rw-r--r-- | drivers/base/dma-buf.c | 18 |
1 files changed, 11 insertions, 7 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))) + ptr = NULL; + if (!ptr) goto out_unlock; dmabuf->vmap_ptr = ptr; |