On 12/15/2017 09:03 PM, Jordan Crouse wrote:

On Thu, Dec 14, 2017 at 11:11:50AM +0530, Archit Taneja wrote:

...

The msm/kms driver should work even if there is no GPU device specified in DT. Currently, we get a NULL dereference crash in adreno_load_gpu since the driver assumes that priv->gpu_pdev is non-NULL.

Perform an additional check on priv->gpu_pdev before trying to retrieve the msm_gpu pointer from it.

Fixes: eec874ce5ff1 (drm/msm/adreno: load gpu at probe/bind time)

Signed-off-by: Archit Taneja architt@codeaurora.org

drivers/gpu/drm/msm/adreno/adreno_device.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c index 05022ea2a007..ac60cf3c794e 100644 --- a/drivers/gpu/drm/msm/adreno/adreno_device.c +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c @@ -124,10 +124,17 @@ const struct adreno_info *adreno_info(struct adreno_rev rev) struct msm_gpu *adreno_load_gpu(struct drm_device *dev) { struct msm_drm_private *priv = dev->dev_private;

• struct platform_device *pdev = priv->gpu_pdev;
• struct msm_gpu *gpu = platform_get_drvdata(priv->gpu_pdev);

• struct platform_device *pdev;

• struct msm_gpu *gpu; int ret;

• pdev = priv->gpu_pdev;

• if (!pdev) {

• dev_dbg(dev->dev, "no adreno platform device found\n");
  

• return NULL;
  

• }

• gpu = platform_get_drvdata(pdev); if (!gpu) { dev_err(dev->dev, "no adreno device\n"); return NULL;

Obviously correct fix but I can't help but think that we should share the same error message, so something like:

struct msm_gpu *gpu = NULL;

..

if (priv->gpu_pdev) gpu = platform_get_drvdata(priv->gpu_pdev);

if (!gpu) { dev_err(dev->dev, "No GPU device was was found\n"); return NULL; }

(also, I can't help but think maybe that dev_err should be a ONCE so you don't get a nasty message every time you open the file descriptor).

This approach looks better. I'll re-spin.

Thanks, Archit

Jordan

On Fri, Dec 22, 2017 at 03:41:13PM +0530, Archit Taneja wrote:

The msm/kms driver should work even if there is no GPU device specified in DT. Currently, we get a NULL dereference crash in adreno_load_gpu since the driver assumes that priv->gpu_pdev is non-NULL.

Perform an additional check on priv->gpu_pdev before trying to retrieve the msm_gpu pointer from it.

v2: Incorporate Jordan's comments:

• Simplify the check to share the same error message.
• Use dev_err_once() to avoid an error message every time we open the drm device fd.

Fixes: eec874ce5ff1 (drm/msm/adreno: load gpu at probe/bind time)

Signed-off-by: Archit Taneja architt@codeaurora.org

Acked-by: Jordan Crouse jcrouse@codeaurora.org

---

drivers/gpu/drm/msm/adreno/adreno_device.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c index 05022ea2a007..bfb3d689f47d 100644 --- a/drivers/gpu/drm/msm/adreno/adreno_device.c +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c @@ -125,11 +125,14 @@ struct msm_gpu *adreno_load_gpu(struct drm_device *dev) { struct msm_drm_private *priv = dev->dev_private; struct platform_device *pdev = priv->gpu_pdev;

• struct msm_gpu *gpu = platform_get_drvdata(priv->gpu_pdev);

• struct msm_gpu *gpu = NULL; int ret;

• if (pdev)

• gpu = platform_get_drvdata(pdev);
  

• if (!gpu) {

• dev_err(dev->dev, "no adreno device\n");
  

• dev_err_once(dev->dev, "no GPU device was found\n");
  

  return NULL; }