Messages in this thread | | | Date | Tue, 1 Aug 2023 15:36:33 +0200 | Subject | Re: [PATCH net-next 5/9] page_pool: don't use driver-set flags field directly | From | Alexander Lobakin <> |
| |
From: Yunsheng Lin <linyunsheng@huawei.com> Date: Sat, 29 Jul 2023 19:40:32 +0800
> On 2023/7/28 22:03, Alexander Lobakin wrote: >> From: Yunsheng Lin <linyunsheng@huawei.com> >> Date: Fri, 28 Jul 2023 20:36:50 +0800 >> >>> On 2023/7/27 22:43, Alexander Lobakin wrote: >>> >>>> >>>> struct page_pool { >>>> struct page_pool_params p; >>>> - long pad; >>>> + >>>> + bool dma_map:1; /* Perform DMA mapping */ >>>> + enum { >>>> + PP_DMA_SYNC_ACT_DISABLED = 0, /* Driver didn't ask to sync */ >>>> + PP_DMA_SYNC_ACT_DO, /* Perform DMA sync ops */ >>>> + } dma_sync_act:1; >>>> + bool page_frag:1; /* Allow page fragments */ >>>> >>> >>> Isn't it more common or better to just remove the flags field in >>> 'struct page_pool_params' and pass the flags by parameter like >>> below, so that patch 4 is not needed? >>> >>> struct page_pool *page_pool_create(const struct page_pool_params *params, >>> unsigned int flags); >> >> You would need a separate patch to convert all the page_pool_create() >> users then either way. >> And it doesn't look really natural to me to pass both driver-set params >> and driver-set flags as separate function arguments. Someone may then >> think "why aren't flags just put in the params itself". The fact that >> Page Pool copies the whole params in the page_pool struct after >> allocating it is internals, page_pool_create() prototype however isn't. >> Thoughts? > > It just seems odd to me that dma_map and page_frag is duplicated as we > seems to have the same info in the page_pool->p.flags.
It's just because we copy the whole &page_pool_params passed by the driver. It doesn't look good to me to define a new structure and copy the values field-by-field just to avoid duplicating 3 bits :s
> > What about: > In [PATCH net-next 4/9] page_pool: shrink &page_pool_params a tiny bit, > 'flags' is bit-field'ed with 'dma_dir', what about changing 'dma_dir' > to be bit-field'ed with 'dma_sync_act', so that page_pool->p.flags stays > the same as before, and 'dma_map' & 'page_frag' do not seems be really > needed as we have the same info in page_pool->p.flags?
Not sure I follow :z ::dma_dir is also passed by the driver, so we can't drop it from the params struct.
> > >> >> Thanks, >> Olek >> >> . >>
Thanks, Olek
| |