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Manually rebased* generic/backport-5.4/700-v5.5-net-core-allow-fast-GRO-for-skbs-with-Ethernet-heade.patch Added new backport* generic/backport-5.4/050-gro-fix-napi_gro_frags-Fast-GRO-breakage-due-to-IP-a.patch All others updated automatically. The new backport was included based on this[1] upstream commit that will be mainlined soon. This change is needed because Eric Dumazet's check for NET_IP_ALIGN (landed in 5.4.114) causes huge slowdowns on drivers which use napi_gro_frags(). Build system: x86_64 Build-tested: ipq806x/R7800 Run-tested: ipq806x/R7800 No dmesg regressions, everything functional *Credit to Alexander Lobakin 1. https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=7ad18ff6449cbd6beb26b53128ddf56d2685aa93 Signed-off-by: John Audia <graysky@archlinux.us>
76 lines
2.9 KiB
Diff
76 lines
2.9 KiB
Diff
From 3007b05df4301aad179acc6ca1c3645785576df6 Mon Sep 17 00:00:00 2001
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From: Alexander Lobakin <alobakin@pm.me>
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Date: Mon, 19 Apr 2021 12:53:06 +0000
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Subject: gro: fix napi_gro_frags() Fast GRO breakage due to IP
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alignment check
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Commit 7ad18ff6449cbd6beb26b53128ddf56d2685aa93 upstream.
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Commit 38ec4944b593 ("gro: ensure frag0 meets IP header alignment")
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did the right thing, but missed the fact that napi_gro_frags() logics
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calls for skb_gro_reset_offset() *before* pulling Ethernet header
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to the skb linear space.
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That said, the introduced check for frag0 address being aligned to 4
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always fails for it as Ethernet header is obviously 14 bytes long,
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and in case with NET_IP_ALIGN its start is not aligned to 4.
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Fix this by adding @nhoff argument to skb_gro_reset_offset() which
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tells if an IP header is placed right at the start of frag0 or not.
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This restores Fast GRO for napi_gro_frags() that became very slow
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after the mentioned commit, and preserves the introduced check to
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avoid silent unaligned accesses.
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From v1 [0]:
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- inline tiny skb_gro_reset_offset() to let the code be optimized
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more efficively (esp. for the !NET_IP_ALIGN case) (Eric);
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- pull in Reviewed-by from Eric.
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[0] https://lore.kernel.org/netdev/20210418114200.5839-1-alobakin@pm.me
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Fixes: 38ec4944b593 ("gro: ensure frag0 meets IP header alignment")
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Reviewed-by: Eric Dumazet <edumazet@google.com>
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Signed-off-by: Alexander Lobakin <alobakin@pm.me>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/core/dev.c | 8 ++++----
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1 file changed, 4 insertions(+), 4 deletions(-)
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--- a/net/core/dev.c
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+++ b/net/core/dev.c
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@@ -5395,7 +5395,7 @@ static struct list_head *gro_list_prepar
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return head;
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}
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-static void skb_gro_reset_offset(struct sk_buff *skb)
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+static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
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{
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const struct skb_shared_info *pinfo = skb_shinfo(skb);
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const skb_frag_t *frag0 = &pinfo->frags[0];
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@@ -5407,7 +5407,7 @@ static void skb_gro_reset_offset(struct
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if (skb_mac_header(skb) == skb_tail_pointer(skb) &&
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pinfo->nr_frags &&
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!PageHighMem(skb_frag_page(frag0)) &&
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- (!NET_IP_ALIGN || !(skb_frag_off(frag0) & 3))) {
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+ (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
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NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
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NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
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skb_frag_size(frag0),
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@@ -5640,7 +5640,7 @@ gro_result_t napi_gro_receive(struct nap
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skb_mark_napi_id(skb, napi);
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trace_napi_gro_receive_entry(skb);
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- skb_gro_reset_offset(skb);
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+ skb_gro_reset_offset(skb, 0);
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ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
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trace_napi_gro_receive_exit(ret);
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@@ -5733,7 +5733,7 @@ static struct sk_buff *napi_frags_skb(st
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napi->skb = NULL;
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skb_reset_mac_header(skb);
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- skb_gro_reset_offset(skb);
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+ skb_gro_reset_offset(skb, hlen);
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if (unlikely(skb_gro_header_hard(skb, hlen))) {
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eth = skb_gro_header_slow(skb, hlen, 0);
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