lkml.org 
[lkml]   [2022]   [Jan]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH 13/14] net: inline part of skb_csum_hwoffload_help
Date
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.)

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
\
 
 \ /
  Last update: 2022-01-11 18:26    [W:0.061 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site