On 2023/12/22 5:22, Mina Almasry wrote: > On Thu, Dec 21, 2023 at 3:32 AM Yunsheng Lin <linyunsheng@xxxxxxxxxx> wrote: >> >> On 2023/12/20 11:01, Mina Almasry wrote: >> >> ... >> >>>>>> Perhaps we should aim to not export netmem_to_page(), >>>>>> prevent modules from accessing it directly. >>>>> >>>>> +1. >>>> >>> >>> I looked into this, but it turns out it's a slightly bigger change >>> that needs some refactoring to make it work. There are few places >>> where I believe I need to add netmem_to_page() that are exposed to the >>> drivers via inline helpers, these are: >>> >>> - skb_frag_page(), which returns NULL if the netmem is not a page, but >>> needs to do a netmem_to_page() to return the page otherwise. >> >> Is it possible to introduce something like skb_frag_netmem() for >> netmem? so that we can keep most existing users of skb_frag_page() >> unchanged and avoid adding additional checking overhead for existing >> users. >> > > In my experience most current skb_frag_page() users need specifically > the struct page*. Example is illegal_highdma() which > PageHighMem(skb_frag_page()) For illegal_highdma() case, is it possible to use something like skb_readabe_frag() checking to avoid calling skb_frag_page() for netmem? > > But RFC v5 adds skb_frag_netmem() for callsites that want a netmem and > don't care about specifically a page: > > https://patchwork.kernel.org/project/netdevbpf/patch/20231218024024.3516870-10-almasrymina@xxxxxxxxxx/ > >>> - The helpers inside skb_add_rx_frag(), which needs to do a >>> netmem_to_page() to set skb->pfmemalloc. >> >> Similar as above, perhaps introduce something like skb_add_rx_netmem_frag()? >> > > Yes, v3 of this series adds skb_add_rx_frag_netmem(): > > https://patchwork.kernel.org/project/netdevbpf/patch/20231220214505.2303297-4-almasrymina@xxxxxxxxxx/
