replace sq_mask with ring_mask

replace sq_mask with ring_mask

[JackieLiu]

Hello Jens Axboe

Could we replace ctx->sq_mask/ctx->cq_mask with cq_ring->ring_mask
/sq_ring->ring_mask ? because it’s a constant and never change in 
io_uring.c

I found that ctx->sq_mask just used on 

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/io_uring.c?h=v5.1#n1831

and we can replace like follow:

- head = READ_ONCE(ring->array[head & ctx->sq_mask]);
+ head = READ_ONCE(ring->array[head & ring->ring_mask]);

If I understand incorrectly, please point out.

Jackie Liu

Re: replace sq_mask with ring_mask

[Jens Axboe]

On 5/15/19 12:47 AM, JackieLiu wrote:
> Hello Jens Axboe
> 
> Could we replace ctx->sq_mask/ctx->cq_mask with cq_ring->ring_mask
> /sq_ring->ring_mask ? because it’s a constant and never change in 
> io_uring.c
> 
> I found that ctx->sq_mask just used on 
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/io_uring.c?h=v5.1#n1831
> 
> and we can replace like follow:
> 
> - head = READ_ONCE(ring->array[head & ctx->sq_mask]);
> + head = READ_ONCE(ring->array[head & ring->ring_mask]);
> 
> If I understand incorrectly, please point out.

We could, but we cache it in the kernel since the ring value could
potentially be modified by the application.

-- 
Jens Axboe