[PATCH 13/34] drm/amdgpu: Convert ctx_handles to XArray

[Koenig, Christian]

Am 25.02.19 um 17:39 schrieb Matthew Wilcox:
> On Mon, Feb 25, 2019 at 05:07:24PM +0100, Christian König wrote:
>>> -#define AMDGPU_VM_MAX_NUM_CTX			4096
>>> +#define AMDGPU_VM_CTX_LIMIT			XA_LIMIT(0, 4095)
>> IIRC we actually use 0 as reserved context value in some places.
> That's OK; the ALLOC1 prevents it from using index 0.
>
> You can change it to be XA_LIMIT(1, 4095) if you think that'll be clearer;
> it'll be slightly less efficient assembly (a 64-bit mov-immediate instead
> of a 32-bit mov-immediate), but it's your driver, so it's up to you.

A code comment should do as well.

But thinking more about it please DON'T actually change the 
AMDGPU_VM_MAX_NUM_CTX define.

That one needs to be used to calculate the reserved GPU space to map the 
context save area, and I really don't want to deal with a XA_LIMIT in 
that calculation :)

I'm really wondering why that doesn't go up in a boom during compilation....

Christian.

>
>>> @@ -533,22 +533,18 @@ int amdgpu_ctx_wait_prev_fence(struct amdgpu_ctx *ctx,
>>>    void amdgpu_ctx_mgr_init(struct amdgpu_ctx_mgr *mgr)
>>>    {
>>>    	mutex_init(&mgr->lock);
>>> -	idr_init(&mgr->ctx_handles);
>>> +	xa_init_flags(&mgr->ctx_handles, XA_FLAGS_ALLOC1);
>>>    }
>>>    void amdgpu_ctx_mgr_entity_flush(struct amdgpu_ctx_mgr *mgr)
>>>    {