答复: [PATCH] drm/amdgpu:fix race condition

[Liu, Monk]

Is that so ?

Seq is already type of "uint64_t", GCC still compiles ~0 as 0xffffffff, but not 0xffffffffffffffff ?
I'll change to use ~0ull anyway, 

BR Monk


-----邮件原件-----
发件人: Christian König [mailto:deathsimple at vodafone.de] 
发送时间: Monday, April 10, 2017 4:10 PM
收件人: Liu, Monk <Monk.Liu at amd.com>; amd-gfx at lists.freedesktop.org
主题: Re: [PATCH] drm/amdgpu:fix race condition

Am 10.04.2017 um 09:39 schrieb Monk Liu:
> sequence is protected by spinlock so don't access sequence in paramter 
> seq when invoking this function.
>
> ~0 means to get the latest sequence number and 0 means none to get.

Well you are still not using ~0ull as I said. Using ~0 here will cause 0xffffffff to be used instead of 0xffffffffffffffff.

Additional to that please add a define into amdgpu_drm.h to document this interface change.

Christian.

>
> Change-Id: Ib7a03f3cf5594deeb4ad333cc59b47a6bddfd1ad
> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index 6d86eae..c24bb90 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -277,6 +277,9 @@ struct fence *amdgpu_ctx_get_fence(struct 
> amdgpu_ctx *ctx,
>   
>   	spin_lock(&ctx->ring_lock);
>   
> +	if (seq == ~0)
> +		seq = ctx->rings[ring->idx].sequence - 1;
> +
>   	if (seq >= cring->sequence) {
>   		spin_unlock(&ctx->ring_lock);
>   		return ERR_PTR(-EINVAL);