[Devel] Re: [RFC][PATCH 0/5] uts namespaces: Introduction

[Eric W. Biederman]

"Serge E. Hallyn" <serue at us.ibm.com> writes:

> Quoting Eric W. Biederman (ebiederm at xmission.com):
>> "Serge E. Hallyn" <serue at us.ibm.com> writes:
>> 
>> > Introduce utsname namespaces.  Instead of a single system_utsname
>> > containing hostname domainname etc, a process can request it's
>> > copy of the uts info to be cloned.  The data will be copied from
>> > it's original, but any further changes will not be seen by processes
>> > which are not it's children, and vice versa.
>> >
>> > This is useful, for instance, for vserver/openvz, which can now clone
>> > a new uts namespace for each new virtual server.
>> >
>> > This patchset is based on Kirill Korotaev's Mar 24 submission, taking
>> > comments (in particular from James Morris and Eric Biederman) into
>> > account.
>> >
>> > Some performance results are attached.  I was mainly curious whether
>> > it would be worth putting the task_struct->uts_ns pointer inside
>> > a #ifdef CONFIG_UTS_NS.  The result show that leaving it in when
>> > CONFIG_UTS_NS=n has negligable performance impact, so that is the
>> > approach this patch takes.
>> 
>> Ok.  This looks like the best version so far.
>> 
>> I like the utsname() function thing to shorten the 
>> idiom of  current->uts_ns->name.
>> 
>> We probably want to introduce utsname() and an init_utsname()
>> before any of the other changes, and then perform the substitutions,
>
> This is the same as what Sam is saying, right?  Just making sure I
> understand.

Yes.

>> before we actually change the code so the patchset can make it
>> through a git-bisect.  This will also allows for something
>
> Ok, I've finally got the rest of git doing my bidding, I'll go read
> up on git-bisect.

Basically git-bisect is an automated binary search through patches
to help find bugs.  If you ever can't compile at an intermediate
patch git-bisect and other people walking through the patches
looking for bugs won't like it.

It's not mandatory that you never break anything in a patchset,
but it is much friendlier when you can avoid breakage.

Eric