Messages in this thread | | | Date | Thu, 6 Jun 2019 16:24:22 +0300 | From | Ivan Khoronzhuk <> | Subject | Re: [PATCH v3 net-next 0/7] net: ethernet: ti: cpsw: Add XDP support |
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On Thu, Jun 06, 2019 at 10:08:50AM +0200, Jesper Dangaard Brouer wrote: >On Wed, 05 Jun 2019 12:14:50 -0700 (PDT) >David Miller <davem@davemloft.net> wrote: > >> From: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> >> Date: Wed, 5 Jun 2019 16:20:02 +0300 >> >> > This patchset adds XDP support for TI cpsw driver and base it on >> > page_pool allocator. It was verified on af_xdp socket drop, >> > af_xdp l2f, ebpf XDP_DROP, XDP_REDIRECT, XDP_PASS, XDP_TX. >> >> Jesper et al., please give this a good once over. > >The issue with merging this, is that I recently discovered two bug with >page_pool API, when using DMA-mappings, which result in missing >DMA-unmap's. These bugs are not "exposed" yet, but will get exposed >now with this drivers. > >The two bugs are: > >#1: in-flight packet-pages can still be on remote drivers TX queue, >while XDP RX driver manage to unregister the page_pool (waiting 1 RCU >period is not enough). > >#2: this patchset also introduce page_pool_unmap_page(), which is >called before an XDP frame travel into networks stack (as no callback >exist, yet). But the CPUMAP redirect *also* needs to call this, else we >"leak"/miss DMA-unmap. > >I do have a working prototype, that fixes these two bugs. I guess, I'm >under pressure to send this to the list soon...
In particular "cpsw" case no dma unmap issue and if no changes in page_pool API then no changes to the driver required. page_pool_unmap_page() is used here for consistency reasons with attention that it can be inherited/reused by other SoCs for what it can be relevant.
One potential change as you mentioned is with dropping page_pool_destroy() that, now, can look like:
@@ -571,7 +571,6 @@ static void cpsw_destroy_rx_pool(struct cpsw_priv *priv, int ch) return;
xdp_rxq_info_unreg(&priv->xdp_rxq[ch]); - page_pool_destroy(priv->page_pool[ch]); priv->page_pool[ch] = NULL; }
From what I know there is ongoing change for adding switchdev to cpsw that can change a lot and can require more work to rebase / test this patchset, so I want to believe it can be merged before this.
-- Regards, Ivan Khoronzhuk
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