Re: [GIT PULL] [IPV6] COMPAT: Fix SSM applications on 64bit kernels.

[David Miller <davem@davemloft.net>]

From: YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@linux-ipv6.org>
Date: Fri, 25 Apr 2008 15:59:22 +0900 (JST)

> In article <20080424.234748.53723057.davem@davemloft.net> (at Thu, 24 Apr 2008 23:47:48 -0700 (PDT)), David Miller <davem@davemloft.net> says:
> 
> > From: YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@linux-ipv6.org>
> > Date: Fri, 25 Apr 2008 15:37:33 +0900 (JST)
> > 
> > > In article <20080424.233159.06679047.davem@davemloft.net> (at Thu, 24 Apr 2008 23:31:59 -0700 (PDT)), David Miller <davem@davemloft.net> says:
> > > 
> > > > 1) Use copy_in_user() as that's the proper interaface to copy within
> > > >    userspace in COMPAT code.
> > > 
> > > So, don't we care increase of copy operation with it?
> > 
> > I think for now it's an OK tradeoff, but yes it does increase
> > copies.  But then again, many compat layer handlers do.
> 
> And in IPv4, group_XXX{} handlers are even wrappers for ip_mreqXXX{}
> handlers so we we have another copy...

It is always possible to simplify things and make them more efficient.
And we should always do that.

The priority at the moment should be the simplist bug fix.