[PATCH] drm/amdgpu: fix the memory corruption on S3

[Huang Rui]

On Thu, Jun 29, 2017 at 03:34:57PM +0800, Michel Dänzer wrote:
> On 29/06/17 04:03 PM, Huang Rui wrote:
> > psp->cmd will be used on resume phase, so we can not free it on hw_init.
> > Otherwise, a memory corruption will be triggered.
> >
> > Signed-off-by: Huang Rui <ray.huang at amd.com>
> > ---
> >
> > Alex, Christian,
> >
> > This is the final fix for vega10 S3. The random memory corruption issue is
> root
> > caused.
> >
> > Thanks,
> > Ray
> >
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c b/drivers/gpu/drm/amd/
> amdgpu/amdgpu_psp.c
> > index 5041073..fcdd542 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
> > @@ -372,8 +372,6 @@ static int psp_load_fw(struct amdgpu_device *adev)
> >        if (ret)
> >                goto failed_mem;
> > 
> > -     kfree(cmd);
> > -
> >        return 0;
> 
> This looks like a good catch.
> 
> 
> > @@ -384,6 +382,7 @@ static int psp_load_fw(struct amdgpu_device *adev)
> >                              &psp->fw_pri_mc_addr, &psp->fw_pri_buf);
> >  failed:
> >        kfree(cmd);
> > +     cmd = NULL;
> 
> This should probably be
> 
>         psp->cmd = NULL;
> 
> instead?
> 

Actually, we set psp->cmd = cmd before.

But anyway, we needn't "cmd" member any more.

> 
> > @@ -443,6 +442,11 @@ static int psp_hw_fini(void *handle)
> >                amdgpu_bo_free_kernel(&psp->fence_buf_bo,
> >                                      &psp->fence_buf_mc_addr, &psp->
> fence_buf);
> > 
> > +     if (!psp->cmd) {
> > +             kfree(psp->cmd);
> > +             psp->cmd = NULL;
> > +     }
> 
> This should probably be
> 
>         if (psp->cmd) {
> 
> ? If so, you could skip the if altogether, since kfree(NULL) is safe.

Nice catch. My typo. ;-)

You're right. Will update it in V2.

Thanks,
Rui