[PATCH] drm/amdgpu: clear seq64 memory on free

[Christian König]

Am 15.04.24 um 20:48 schrieb Arunpravin Paneer Selvam:
> We should clear the memory on free. Otherwise,
> there is a chance that we will access the previous
> application data and this would leads to an abnormal
> behaviour in the current application.

Mhm, I would strongly expect that we initialize the seq number after 
allocation.

It could be that we also have situations were the correct start value is 
0xffffffff or something like that instead.

Why does this matter?

Regards,
Christian.

>
> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c
> index 4b9afc4df031..9613992c9804 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c
> @@ -189,10 +189,14 @@ int amdgpu_seq64_alloc(struct amdgpu_device *adev, u64 *va, u64 **cpu_addr)
>   void amdgpu_seq64_free(struct amdgpu_device *adev, u64 va)
>   {
>   	unsigned long bit_pos;
> +	u64 *cpu_addr;
>   
>   	bit_pos = (va - amdgpu_seq64_get_va_base(adev)) / sizeof(u64);
> -	if (bit_pos < adev->seq64.num_sem)
> +	if (bit_pos < adev->seq64.num_sem) {
> +		cpu_addr = bit_pos + adev->seq64.cpu_base_addr;
> +		memset(cpu_addr, 0, sizeof(u64));
>   		__clear_bit(bit_pos, adev->seq64.used);
> +	}
>   }
>   
>   /**