Re: [dpdk-dev] [PATCH v6 3/4] bond mode 4: allow external state machine

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-11-03 10:30, Panu Matilainen:
> On 11/03/2015 10:16 AM, Thomas Monjalon wrote:
> > 2015-11-03 08:48, Panu Matilainen:
> >> On 11/02/2015 06:42 PM, Eric Kinzie wrote:
> >>> On Mon Nov 02 12:23:47 +0200 2015, Panu Matilainen wrote:
> >>>> On 11/01/2015 08:17 PM, Thomas Monjalon wrote:
> >>>>> 2015-10-19 08:36, Eric Kinzie:
> >>>>>>     Size of struct rte_eth_bond_8023ad_conf changed.  Increment LIBABIVER
> >>>>>>     and version bond_mode_8023ad_setup and bond_mode_8023ad_conf_get
> >>>>>>     functions.
> >>>>> [...]
> >>>>>> +VERSION_SYMBOL(bond_mode_8023ad_setup, _v20, 2.0);
> >>>>> [...]
> >>>>>> +BIND_DEFAULT_SYMBOL(bond_mode_8023ad_setup, _v22, 2.2);
> >>>>>> +MAP_STATIC_SYMBOL(void bond_mode_8023ad_setup(struct rte_eth_dev *dev, struct rte_eth_bond_8023ad_conf *conf), \
> >>>>>> +		  bond_mode_8023ad_setup_v22);
> >>>>>
> >>>>> I'm sorry it doesn't work well when trying to build a combined lib:
> >>>>>
> >>>>> ld: libdpdk.so: version node not found for symbol bond_mode_8023ad_setup@@DPDK_2.2
> >>>>>
> >>>>> The symbols are OK in the .o file:
> >>>>> 0000000000002340 g     F .text  0000000000000171 bond_mode_8023ad_setup@@DPDK_2.2
> >>>>> 0000000000002260 g     F .text  00000000000000da bond_mode_8023ad_setup@DPDK_2.0
> >>>>> 0000000000002260 g     F .text  00000000000000da bond_mode_8023ad_setup_v20
> >>>>> 0000000000002340 g     F .text  0000000000000171 bond_mode_8023ad_setup_v22
> >>>>> 0000000000000000         *UND*  0000000000000000 bond_mode_8023ad_setup
> >>>>>
> >>>>> I don't understand the problem and I am considering disabling versioning in
> >>>>> combined library.
> >>>>>
> >>>>> Any idea?
> >>>>>
> >>>>
> >>>> The .map additions look incorrect to me:
> >>>>
> >>>>> diff --git a/drivers/net/bonding/rte_eth_bond_version.map b/drivers/net/bonding/rte_eth_bond_version.map
> >>>>> index 22bd920..7f78717 100644
> >>>>> --- a/drivers/net/bonding/rte_eth_bond_version.map
> >>>>> +++ b/drivers/net/bonding/rte_eth_bond_version.map
> >>>>> @@ -17,6 +17,9 @@  DPDK_2.0 {
> >>>>> 	rte_eth_bond_slaves_get;
> >>>>> 	rte_eth_bond_xmit_policy_get;
> >>>>> 	rte_eth_bond_xmit_policy_set;
> >>>>> +	rte_eth_bond_8023ad_ext_collect;
> >>>>> +	rte_eth_bond_8023ad_ext_distrib;
> >>>>> +	rte_eth_bond_8023ad_ext_slowtx;
> >>>>
> >>>> These symbols didn't exist in DPDK 2.0 but are only being added
> >>>> here. So why are they being added to the 2.0 section?
> >>>
> >>> Yes, I think these should probably be moved.
> >>>
> >>>
> >>>>>
> >>>>> 	local: *;
> >>>>> };
> >>>>> @@ -27,3 +30,10 @@  DPDK_2.1 {
> >>>>> 	rte_eth_bond_free;
> >>>>>
> >>>>> } DPDK_2.0;
> >>>>> +
> >>>>> +DPDK_2.2 {
> >>>>> +	local
> >>>>> +
> >>>>> +	bond_mode_8023ad_conf_get;
> >>>>> +	bond_mode_8023ad_setup;
> >>>>> +} DPDK_2.1;
> >>>>
> >>>> These are marked local, as in, "not exported" which doesn't seem
> >>>> right. Also they're lacking the rte_eth_ prefix. AFAICS this is what
> >>>> the symbol export map should look like here:
> >>>
> >>>
> >>> These were not exported to begin with.  But after versioning these
> >>> functions, they are exported unless explicitly declared to be local here.
> >>>
> >>
> >> And this does not ring any warning bells? :)
> >>
> >> Sorry, I was not looking at the patch as a whole. You're declaring these
> >> symbols as exported with the versioning macros, eg
> >>
> >> BIND_DEFAULT_SYMBOL(bond_mode_8023ad_setup, _v22, 2.2);
> >>
> >> ...and then explicitly telling it to not export them by declaring local,
> >> and then we wonder why it has trouble finding the symbols.
> >> The versioning macros wont invent the librte_ prefix for you, you need
> >> to rename the functions accordingly.
> >>
> >> But all this versioning gymnastics is moot anyway because you declare
> >> the ABI incompatible:
> >>
> >> -LIBABIVER := 1
> >> +LIBABIVER := 2
> >>
> >> This changes the library soname, so no binary compiled against the
> >> previous version can possibly use it anymore. As in, by definition there
> >> can be no callers of the _v20 variants after this ABI version bump.
> >
> > Panu, thanks for your careful review.
> > We must remove the private functions from the export map.and not bump LIBABIVER.
> 
> Actually the LIBABIVER bump seems appropriate since a public struct 
> (rte_eth_bond_8023ad_conf) changes size.

Not sure. It is added at the end of a struct which is not embedded elsewhere.

> As for the rest, I'm not quite sure what the patch is trying to achieve. 
> I initially assumed its trying to add a new incompatible version of 
> rte_bond_mode_8023ad_setup() and rte_eth_bond_8023ad_conf_get() which 
> could be a perfectly reasonable thing to do in some circumstances. As it 
> is, the patch actually adds versioning to an internal symbol which just 
> doesn't make sense at all. Symbol versioning is only meaningful for 
> public symbols.

Yes