Re: [PATCH net-next 2/3] page_pool: Turn dma_sync and dma_sync_cpu fields into a bitmap

["Toke Høiland-Jørgensen" <toke@redhat.com>]

Yunsheng Lin <yunshenglin0825@gmail.com> writes:

> On 3/14/2025 6:10 PM, Toke Høiland-Jørgensen wrote:
>> Change the single-bit booleans for dma_sync into an unsigned long with
>> BIT() definitions so that a subsequent patch can write them both with a
>> singe WRITE_ONCE() on teardown. Also move the check for the sync_cpu
>> side into __page_pool_dma_sync_for_cpu() so it can be disabled for
>> non-netmem providers as well.
>
> I guess this patch is for the preparation of disabling the
> page_pool_dma_sync_for_cpu() related API on teardown?
>
> It seems unnecessary that page_pool_dma_sync_for_cpu() related API need
> to be disabled on teardown as page_pool_dma_sync_for_cpu() has the same
> calling assumption as the alloc API, which is not supposed to be called
> by the drivers when page_pool_destroy() is called.

Sure, we could keep it to the dma_sync_for_dev() direction only, but
making both directions use the same variable to store the state, and
just resetting it at once, seemed simpler and more consistent.

-Toke