netdev - Re: [PATCH net-next v5 1/3] net: ipv6: Unduplicate {raw,udp}v6

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Message-ID: <20140425171909.GB7050@order.stressinduktion.org>
Date:	Fri, 25 Apr 2014 19:19:09 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	David Miller <davem@...emloft.net>
Cc:	David.Laight@...LAB.COM, lorenzo@...gle.com,
	netdev@...r.kernel.org, yoshfuji@...ux-ipv6.org,
	eric.dumazet@...il.com
Subject: Re: [PATCH net-next v5 1/3] net: ipv6: Unduplicate {raw,udp}v6_sendmsg code

On Fri, Apr 25, 2014 at 12:51:55PM -0400, David Miller wrote:
> From: David Laight <David.Laight@...LAB.COM>
> Date: Fri, 25 Apr 2014 11:24:21 +0000
> 
> > From: Lorenzo Colitti
> >> rawv6_sendmsg and udpv6_sendmsg have ~100 lines of almost
> >> identical code. Move this into a new ipv6_datagram_send_common
> >> helper function.
> >> 
> >> Tested: black-box tested using user-mode Linux.
> >> 
> >> - Basic UDP sends using sendto work.
> >> - Mark routing and oif routing using SO_BINDTODEVICE work.
> > ...
> >> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> >> index d640925..f1a247a 100644
> >> --- a/include/net/ipv6.h
> >> +++ b/include/net/ipv6.h
> >> @@ -785,6 +785,13 @@ int compat_ipv6_getsockopt(struct sock *sk, int level, int optname,
> >>  int ip6_datagram_connect(struct sock *sk, struct sockaddr *addr, int addr_len);
> >>  int ip6_datagram_connect_v6_only(struct sock *sk, struct sockaddr *addr,
> >>  				 int addr_len);
> >> +int ip6_datagram_send_common(struct sock *sk, struct msghdr *msg,
> >> +			     struct sockaddr_in6 *sin6, int addr_len,
> >> +			     struct flowi6 *fl6, struct dst_entry **dstp,
> >> +			     struct ipv6_txoptions **optp,
> >> +			     struct ipv6_txoptions *opt_space,
> >> +			     int *hlimit, int *tclass, int *dontfrag,
> >> +			     int *connected);
> > 
> > That is a lot of parameters! and udp send is probably an important path.
> 
> The more I read this series the more I dislike it.
> 
> All of these pointers being passed in, were local variables in the
> original code.
> 
> This consolidation makes the code much worse, not better.

Maybe we can put all those hlimit, tclass, dontfrag vars into a struct
and just pass one pointer.

Also it could be possible to just do that by value if return slot optimization
in gcc optimizes that away.

Greetings,

  Hannes

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