Messages in this thread | | | Date | Tue, 2 Jul 2019 21:58:40 +0300 | From | Ivan Khoronzhuk <> | Subject | Re: [PATCH] net: core: page_pool: add user refcnt and reintroduce page_pool_destroy |
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On Tue, Jul 02, 2019 at 08:29:07PM +0200, Jesper Dangaard Brouer wrote: >On Tue, 2 Jul 2019 18:21:13 +0300 >Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> wrote: > >> On Tue, Jul 02, 2019 at 05:10:29PM +0200, Jesper Dangaard Brouer wrote: >> >On Tue, 2 Jul 2019 17:56:13 +0300 >> >Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> wrote: >> > >> >> On Tue, Jul 02, 2019 at 04:52:30PM +0200, Jesper Dangaard Brouer wrote: >> >> >On Tue, 2 Jul 2019 17:44:27 +0300 >> >> >Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> wrote: >> >> > >> >> >> On Tue, Jul 02, 2019 at 04:31:39PM +0200, Jesper Dangaard Brouer wrote: >> >> >> >From: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> >> >> >> > >> >> >> >Jesper recently removed page_pool_destroy() (from driver invocation) and >> >> >> >moved shutdown and free of page_pool into xdp_rxq_info_unreg(), in-order to >> >> >> >handle in-flight packets/pages. This created an asymmetry in drivers >> >> >> >create/destroy pairs. >> >> >> > >> >> >> >This patch add page_pool user refcnt and reintroduce page_pool_destroy. >> >> >> >This serves two purposes, (1) simplify drivers error handling as driver now >> >> >> >drivers always calls page_pool_destroy() and don't need to track if >> >> >> >xdp_rxq_info_reg_mem_model() was unsuccessful. (2) allow special cases >> >> >> >where a single RX-queue (with a single page_pool) provides packets for two >> >> >> >net_device'es, and thus needs to register the same page_pool twice with two >> >> >> >xdp_rxq_info structures. >> >> >> >> >> >> As I tend to use xdp level patch there is no more reason to mention (2) case >> >> >> here. XDP patch serves it better and can prevent not only obj deletion but also >> >> >> pool flush, so, this one patch I could better leave only for (1) case. >> >> > >> >> >I don't understand what you are saying. >> >> > >> >> >Do you approve this patch, or do you reject this patch? >> >> > >> >> It's not reject, it's proposition to use both, XDP and page pool patches, >> >> each having its goal. >> > >> >Just to be clear, if you want this patch to get accepted you have to >> >reply with your Signed-off-by (as I wrote). >> > >> >Maybe we should discuss it in another thread, about why you want two >> >solutions to the same problem. >> >> If it solves same problem I propose to reject this one and use this: >> https://lkml.org/lkml/2019/7/2/651 > >No, I propose using this one, and rejecting the other one.
There is at least several arguments against this one (related (2) purpose)
It allows: - avoid changes to page_pool/mlx5/netsec - save not only allocator obj but allocator "page/buffer flush" - buffer flush can be present not only in page_pool but for other allocators that can behave differently and not so simple solution. - to not limit cpsw/(potentially others) to use "page_pool" allocator only ....
This patch better leave also, as it simplifies error path for page_pool and have more error prone usage comparing with existent one.
Please, don't limit cpsw and potentially other drivers to use only page_pool it can be zca or etc... I don't won't to modify each allocator. I propose to add both as by fact they solve different problems with common solution.
-- Regards, Ivan Khoronzhuk
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