Re: [PATCH net-next v3 2/7] dma: avoid redundant calls for sync operations

[Christoph Hellwig]

On Wed, Feb 14, 2024 at 05:55:23PM +0000, Robin Murphy wrote:
>>   #define DMA_F_PCI_P2PDMA_SUPPORTED     (1 << 0)
>> +#define DMA_F_CAN_SKIP_SYNC		BIT(1)
>
> Yuck, please be consistent - either match the style of the existing code, 
> or change that to BIT(0) as well.

Just don't use BIT() ever.  It doesn't save any typing and creates a
totally pointless mental indirection.

> I guess this was the existing condition from dma_need_sync(), but now it's 
> on a one-off slow path it might be nice to check the sync_sg_* ops as well 
> for completeness, or at least comment that nobody should be implementing 
> those without also implementing the sync_single_* ops.

Implementing only one and not the other doesn't make any sense.  Maybe
a debug check for that is ok, but thing will break badly if they aren't
in sync anyway.