Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL
On Sat, Dec 21, 2013 at 07:42:17AM -0500, Rob Clark wrote: On Fri, Dec 20, 2013 at 7:43 PM, Colin Cross ccr...@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 ccr...@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. Yeah, I don't like this, it could cause unnecessary reports of problems. Care to fix it up? thanks, greg k-h -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL
On Fri, Feb 7, 2014 at 8:43 AM, Greg Kroah-Hartman gre...@linuxfoundation.org wrote: On Sat, Dec 21, 2013 at 07:42:17AM -0500, Rob Clark wrote: On Fri, Dec 20, 2013 at 7:43 PM, Colin Cross ccr...@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 ccr...@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. Yeah, I don't like this, it could cause unnecessary reports of problems. The WARN_ON_ONCE is only if the vmap op returns ERR_PTR, not if it returns NULL. This is designed to catch vmap ops that don't follow the spec, so I would call them necessary reports, but I can take it out if you still disagree. -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL
On Fri, Feb 07, 2014 at 09:22:37AM -0800, Colin Cross wrote: On Fri, Feb 7, 2014 at 8:43 AM, Greg Kroah-Hartman gre...@linuxfoundation.org wrote: On Sat, Dec 21, 2013 at 07:42:17AM -0500, Rob Clark wrote: On Fri, Dec 20, 2013 at 7:43 PM, Colin Cross ccr...@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 ccr...@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. Yeah, I don't like this, it could cause unnecessary reports of problems. The WARN_ON_ONCE is only if the vmap op returns ERR_PTR, not if it returns NULL. This is designed to catch vmap ops that don't follow the spec, so I would call them necessary reports, but I can take it out if you still disagree. Ah, ok, that makes more sense. I'll queue this up. thanks, greg k-h -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL
Em Sat, 21 Dec 2013 07:42:17 -0500 Rob Clark robdcl...@gmail.com escreveu: On Fri, Dec 20, 2013 at 7:43 PM, Colin Cross ccr...@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 ccr...@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 robdcl...@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.che...@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
Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL
On Fri, Dec 20, 2013 at 7:43 PM, Colin Cross ccr...@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 ccr...@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 robdcl...@gmail.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 =