Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH 13/14] net: inline part of skb_csum_hwoffload_help | Date | Wed, 12 Jan 2022 02:41:42 +0000 |
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From: Pavel Begunkov > Sent: 11 January 2022 20:48 > On 1/11/22 17:25, David Laight wrote: > > From: Pavel Begunkov > >> Sent: 11 January 2022 16:59 > >> > >> On 1/11/22 09:24, David Laight wrote: > >>> From: Pavel Begunkov > >>>> Sent: 11 January 2022 01:22 > >>>> > >>>> Inline a HW csum'ed part of skb_csum_hwoffload_help(). > >>>> > >>>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > >>>> --- > >>>> include/linux/netdevice.h | 16 ++++++++++++++-- > >>>> net/core/dev.c | 13 +++---------- > >>>> 2 files changed, 17 insertions(+), 12 deletions(-) > >>>> > >>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > >>>> index 3213c7227b59..fbe6c764ce57 100644 > >>>> --- a/include/linux/netdevice.h > >>>> +++ b/include/linux/netdevice.h > >>>> @@ -4596,8 +4596,20 @@ void netdev_rss_key_fill(void *buffer, size_t len); > >>>> > >>>> int skb_checksum_help(struct sk_buff *skb); > >>>> int skb_crc32c_csum_help(struct sk_buff *skb); > >>>> -int skb_csum_hwoffload_help(struct sk_buff *skb, > >>>> - const netdev_features_t features); > >>>> +int __skb_csum_hwoffload_help(struct sk_buff *skb, > >>>> + const netdev_features_t features); > >>>> + > >>>> +static inline int skb_csum_hwoffload_help(struct sk_buff *skb, > >>>> + const netdev_features_t features) > >>>> +{ > >>>> + if (unlikely(skb_csum_is_sctp(skb))) > >>>> + return !!(features & NETIF_F_SCTP_CRC) ? 0 : > >>> > >>> If that !! doing anything? - doesn't look like it. > >> > >> It doesn't, but left the original style > > > > It just makes you think it is needed... > > > >>>> + skb_crc32c_csum_help(skb); > >>>> + > >>>> + if (features & NETIF_F_HW_CSUM) > >>>> + return 0; > >>>> + return __skb_csum_hwoffload_help(skb, features); > >>>> +} > >>> > >>> Maybe you should remove some bloat by moving the sctp code > >>> into the called function. > >>> This probably needs something like? > >>> > >>> { > >>> if (features & NETIF_F_HW_CSUM && !skb_csum_is_sctp(skb)) > >>> return 0; > >>> return __skb_csum_hw_offload(skb, features); > >>> } > >> > >> I don't like inlining that sctp chunk myself. It seems your way would > >> need another skb_csum_is_sctp() in __skb_csum_hw_offload(), if so I > >> don't think it's worth it. Would've been great to put the > >> NETIF_F_HW_CSUM check first and hide sctp, but don't think it's > >> correct. Would be great to hear some ideas. > > > > Given the definition: > > > > static inline bool skb_csum_is_sctp(struct sk_buff *skb) > > { > > return skb->csum_not_inet; > > } > > > > I wouldn't worry about doing it twice. > > > > Also skb_crc32_csum_help() is only called one. > > Make it static (so inlined) and pass 'features' into it. > > > > In reality sctp is such a slow crappy protocol that a few extra > > function calls will make diddly-squit difference. > > (And yes, we do actually use the sctp stack.) > > I was more thinking about non-sctp path without NETIF_F_HW_CSUM
In which case you need the body of __skb_csum_hw_offload() and end up doing the 'sctp' check once inside it. The 'sctp' check is only done twice for sctp.
David
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