Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL

2014-02-07 Thread Greg Kroah-Hartman
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
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Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL

2014-02-07 Thread Colin Cross
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.
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Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL

2014-02-07 Thread Greg Kroah-Hartman
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
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Re: [PATCH] dma-buf: avoid using IS_ERR_OR_NULL

2013-12-22 Thread Mauro Carvalho Chehab
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

2013-12-21 Thread Rob Clark
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 =