2020-05-28 13:12:16

by Zenghui Yu

Subject: [PATCH] drm/msm/dpu: Fix usage of ERR_PTR()

ERR_PTR() is used in the kernel to encode an usual *negative* errno code
into a pointer. Passing a positive value (ENOMEM) to it will break the
following IS_ERR() check.

Though memory allocation is unlikely to fail, it's still worth fixing.
And grepping shows that this is the only misuse of ERR_PTR() in kernel.

Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
Signed-off-by: Zenghui Yu <[email protected]>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index a1b79ee2bd9d..a2f6b688a976 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -2173,7 +2173,7 @@ struct drm_encoder *dpu_encoder_init(struct drm_device *dev,

dpu_enc = devm_kzalloc(dev->dev, sizeof(*dpu_enc), GFP_KERNEL);
if (!dpu_enc)
- return ERR_PTR(ENOMEM);
+ return ERR_PTR(-ENOMEM);

rc = drm_encoder_init(dev, &dpu_enc->base, &dpu_encoder_funcs,
drm_enc_mode, NULL);
--
2.19.1

2020-06-20 10:32:41

by Zenghui Yu

Subject: Re: [PATCH] drm/msm/dpu: Fix usage of ERR_PTR()

ping for this obvious fix...

On 2020/5/28 21:08, Zenghui Yu wrote:
> ERR_PTR() is used in the kernel to encode an usual *negative* errno code
> into a pointer. Passing a positive value (ENOMEM) to it will break the
> following IS_ERR() check.
>
> Though memory allocation is unlikely to fail, it's still worth fixing.
> And grepping shows that this is the only misuse of ERR_PTR() in kernel.
>
> Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
> Signed-off-by: Zenghui Yu <[email protected]>
> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index a1b79ee2bd9d..a2f6b688a976 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -2173,7 +2173,7 @@ struct drm_encoder *dpu_encoder_init(struct drm_device *dev,
>
> dpu_enc = devm_kzalloc(dev->dev, sizeof(*dpu_enc), GFP_KERNEL);
> if (!dpu_enc)
> - return ERR_PTR(ENOMEM);
> + return ERR_PTR(-ENOMEM);
>
> rc = drm_encoder_init(dev, &dpu_enc->base, &dpu_encoder_funcs,
> drm_enc_mode, NULL);
>

2020-06-20 16:30:05

by Rob Clark

Subject: Re: [PATCH] drm/msm/dpu: Fix usage of ERR_PTR()

On Sat, Jun 20, 2020 at 3:26 AM Zenghui Yu <[email protected]> wrote:
>
> ping for this obvious fix...

Hi, thanks, but there is already a similar fix in msm-next:

commit aa472721c8dbe1713cf510f56ffbc56ae9e14247
Refs: v5.7-rc5-33-gaa472721c8db
Author: Chen Tao <[email protected]>
AuthorDate: Mon Jun 8 09:48:59 2020 +0800
Commit: Rob Clark <[email protected]>
CommitDate: Thu Jun 11 20:07:21 2020 -0700

drm/msm/dpu: fix error return code in dpu_encoder_init

Fix to return negative error code -ENOMEM with the use of
ERR_PTR from dpu_encoder_init.

Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
Signed-off-by: Chen Tao <[email protected]>
Signed-off-by: Rob Clark <[email protected]>


BR,
-R

>
> On 2020/5/28 21:08, Zenghui Yu wrote:
> > ERR_PTR() is used in the kernel to encode an usual *negative* errno code
> > into a pointer. Passing a positive value (ENOMEM) to it will break the
> > following IS_ERR() check.
> >
> > Though memory allocation is unlikely to fail, it's still worth fixing.
> > And grepping shows that this is the only misuse of ERR_PTR() in kernel.
> >
> > Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
> > Signed-off-by: Zenghui Yu <[email protected]>
> > ---
> > drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index a1b79ee2bd9d..a2f6b688a976 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -2173,7 +2173,7 @@ struct drm_encoder *dpu_encoder_init(struct drm_device *dev,
> >
> > dpu_enc = devm_kzalloc(dev->dev, sizeof(*dpu_enc), GFP_KERNEL);
> > if (!dpu_enc)
> > - return ERR_PTR(ENOMEM);
> > + return ERR_PTR(-ENOMEM);
> >
> > rc = drm_encoder_init(dev, &dpu_enc->base, &dpu_encoder_funcs,
> > drm_enc_mode, NULL);
> >