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

[Ferruh Yigit]

On Tue, Nov 03, 2015 at 08:48:16AM +0200, Panu Matilainen wrote:
> 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 at 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.
>
An observation: even soname is different, just renaming .so file itself works.

And this can be useful for the case:
libx.so.1 provides functions A, B, C
app1 compiled against libx.so.1, using only function B

libx.so.1 updated only thefunction A and become libx.so.2
app1 still can run successfully by re-naming lib to libx.so.1 (even soname is libx.so.2)

But for this usage, user needs to know which function updated and is it safe or not to use this library,
I wonder if there is an automatic way of resolving this dependency.


> 	- Panu -
>