Re: [Qemu-devel] [PATCH v2 2/3] net/filter.c: Add Options to insert filters anywhere in the filter list

[Zhang, Chen]

> -----Original Message-----
> From: Lukas Straub <address@hidden>
> Sent: Tuesday, September 3, 2019 2:51 AM
> To: Zhang, Chen <address@hidden>
> Cc: qemu-devel <address@hidden>; Jason Wang
> <address@hidden>; Wen Congyang <address@hidden>;
> Xie Changlong <address@hidden>
> Subject: Re: [PATCH v2 2/3] net/filter.c: Add Options to insert filters
> anywhere in the filter list
> 
> On Mon, 2 Sep 2019 11:43:57 +0000
> "Zhang, Chen" <address@hidden> wrote:
> 
> > > -----Original Message-----
> > > From: Lukas Straub <address@hidden>
> > > Sent: Friday, August 23, 2019 2:21 PM
> > > To: Zhang, Chen <address@hidden>
> > > Cc: qemu-devel <address@hidden>; Jason Wang
> > > <address@hidden>; Wen Congyang
> <address@hidden>; Xie
> > > Changlong <address@hidden>
> > > Subject: Re: [PATCH v2 2/3] net/filter.c: Add Options to insert
> > > filters anywhere in the filter list
> > >
> > > On Fri, 23 Aug 2019 03:24:02 +0000
> > > "Zhang, Chen" <address@hidden> wrote:
> > >
> > > > > -----Original Message-----
> > > > > From: Lukas Straub [mailto:address@hidden]
> > > > > Sent: Friday, August 16, 2019 2:49 AM
> > > > > To: qemu-devel <address@hidden>
> > > > > Cc: Zhang, Chen <address@hidden>; Jason Wang
> > > > > <address@hidden>; Wen Congyang
> > > <address@hidden>; Xie
> > > > > Changlong <address@hidden>
> > > > > Subject: [PATCH v2 2/3] net/filter.c: Add Options to insert
> > > > > filters anywhere in the filter list
> > > > >
> > > > > To switch the Secondary to Primary, we need to insert new
> > > > > filters before the filter-rewriter.
> > > > >
> > > > > Add the options insert= and position= to be able to insert
> > > > > filters anywhere in the filter list.
> > > > >
> > > > > position should be either "head", "tail" or the id of another filter.
> > > > > insert should be either "before" or "after" to specify where to
> > > > > insert the new filter relative to the one specified with position.
> > > > >
> > > >
> > > > Hi Lukas,
> > > >
> > > > It looks no need to add the "insert = xxx" for this operation.
> > > > For example:
> > > >
> > > > We have 3 net-filters, the running order like that:
> > > >
> > > > Fiter1   ---------->   Filter2 ------------> Filter3
> > > >
> > > > If we want to add another filter between filter1 and filter2.
> > > > The "Position = head, insert = after" always seam with "position =
> > > > filter2 id,
> > > insert = before".
> > >
> > > Hi Zhang,
> > > The insert= parameter is ignored if position=head or tail. It always
> > > Inserts at the head (before Filter1) or the tail (after Filter3) of the 
> > > List in
> these cases.
> > >
> > > > It seems the "insert" is a redundant args.
> > > > So I think it is enough with the "position", we can make the
> > > > "insert" always
> > > equal "after" except the "head".
> > >
> > > Yes, we still could do it without it, but its more convenient with
> > > the insert= parameter. For example our Case with inserting before the
> rewriter:
> > >
> > > 'filter-mirror', 'id': 'm0', 'props': { 'insert': 'before', 'position': 
> > > 'rew0',
> 'netdev':
> > > 'hn0', 'queue': 'tx', 'outdev': 'mirror0' } 'filter-redirector', 'id': 
> > > 'redire0',
> 'props':
> > > { 'insert': 'before', 'position': 'rew0', 'netdev': 'hn0', 'queue': 'rx', 
> > > 'indev':
> > > 'compare_out' } 'filter-redirector', 'id': 'redire1', 'props': {
> > > 'insert': 'before',
> > > 'position': 'rew0', 'netdev': 'hn0', 'queue': 'rx', 'outdev':
> > > 'compare0' }
> > >
> > > You see directly that here 3 Filters are inserted before the rewriter.
> > >
> > > would have to become:
> > >
> > > 'filter-mirror', 'id': 'm0', 'props': { 'position': 'head',
> > > 'netdev': 'hn0', 'queue': 'tx',
> > > 'outdev': 'mirror0' } 'filter-redirector', 'id': 'redire0', 'props':
> > > { 'position': 'm0',
> > > 'netdev': 'hn0', 'queue': 'rx', 'indev': 'compare_out' } 
> > > 'filter-redirector', 'id':
> > > 'redire1', 'props': { 'position': 'redire0', 'netdev': 'hn0', 'queue': 
> > > 'rx',
> 'outdev':
> > > 'compare0' }
> > >
> > > Which is less obvious.
> >
> > OK, It is fine for me.
> > But in the code have some other issues like that:
> >
> > +
> > +static void netfilter_set_insert(Object *obj, const char *str, Error
> > +**errp) {
> > +    NetFilterState *nf = NETFILTER(obj);
> > +
> > +    if (strcmp(str, "before") && strcmp(str, "after")) {
> > +        error_setg(errp, "Invalid value for netfilter insert, "
> > +                         "should be 'head' or 'tail'");                    
> >               ----------------------
> ---------->>> I think you should change the "head/tail"  to "before/after".
> 
> Oops, that was a typo.
> 
> > +        return;
> > +    }
> > +
> > +    nf->insert_before = !strcmp(str, "before"); }
> >
> >
> > And I think the "front/behind" is better than "before/after" in this status.
> > At the same time the name of the "insert_before" change to "front_flag" is
> better.
> 
> What I like about the "before" is that it sounds more like an English 
> sentence.
> insert: before, position: rew0
> vs.
> insert: front, position: rew0
> 
> But I agree, "behind" is more clear than "after".
> 
> What do you think about "first/last" instead of "head/tail"?

I'm not a English native speaker, but I think head/tail is enough same as the 
QTAILQ.

Thanks
Zhang Chen

> 
> Regards,
> Lukas Straub
> 
> >
> > Thanks
> > Zhang Chen
> >
> > >
> > > Regards,
> > > Lukas Straub
> > >
> > > >
> > > > Thanks
> > > > Zhang Chen
> > > >
> > > > > Signed-off-by: Lukas Straub <address@hidden>
> > > > > ---
> > > > >  include/net/filter.h |  2 ++
> > > > >  net/filter.c         | 71
> > > +++++++++++++++++++++++++++++++++++++++++++-
> > > > >  qemu-options.hx      | 10 +++----
> > > > >  3 files changed, 77 insertions(+), 6 deletions(-)
> >