Subject: Re: [PATCH v2 iproute] bridge link: add option 'self'

From: Roopa Prabhu <[email-masked]>
Date: Sat, 06 Dec 2014 00:03:30 -0800

On 12/5/14, 9:36 PM, Scott Feldman wrote:
> On Fri, Dec 5, 2014 at 4:59 PM,  <[email-masked]> wrote:
>> From: Roopa Prabhu <[email-masked]>
>>
>> Currently self is set internally only if hwmode is set.
>> This makes it necessary for the hw to have a mode.
>> There is no hwmode really required to go to hardware. So, introduce
>> self for anybody who wants to target hardware.
>>
>> v1 -> v2
>>      - fix a few bugs. Initialize flags to zero: this was required to
>>      keep the current behaviour unchanged.
>>
>> Signed-off-by: Roopa Prabhu <[email-masked]>
>> ---
>>   bridge/link.c |    9 ++++++---
>>   1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/bridge/link.c b/bridge/link.c
>> index 90d9e7f..b8b8675 100644
>> --- a/bridge/link.c
>> +++ b/bridge/link.c
>> @@ -261,7 +261,7 @@ static int brlink_modify(int argc, char **argv)
>>          __s16 priority = -1;
>>          __s8 state = -1;
>>          __s16 mode = -1;
>> -       __u16 flags = BRIDGE_FLAGS_MASTER;
>> +       __u16 flags = 0;
> I don't follow why this change is necessary.  Seems defaulting to
> MASTER unless SELF is set due to "self" or "hwmode" would be more
> correct (and expected).
That flags initialization was always a no-op. IFLA_BRIDGE_FLAGS was 
always set only with the 'self' flag on.
And i don't want to change that unnecessarily with my patch.
Setting it to master now means we will always include IFLA_AF_SPEC with 
IFLA_BRIDGE_FLAGS in every 'bridge setlink' msg.
Which will be a change from the current behavior. And i dont intend to 
introduce it with this patch.

Kernel has always treated no flags as 'master', so we are good from 
kernel perspective.
>
>>          struct rtattr *nest;
>>
>>          memset(&req, 0, sizeof(req));
>> @@ -321,6 +321,8 @@ static int brlink_modify(int argc, char **argv)
>>                                          "\"veb\".\n");
>>                                  exit(-1);
>>                          }
>> +               } else if (strcmp(*argv, "self") == 0) {
>> +                       flags = BRIDGE_FLAGS_SELF;
>>                  } else {
>>                          usage();
>>                  }
>> @@ -375,10 +377,11 @@ static int brlink_modify(int argc, char **argv)
>>           * devices so far.  Thus we only need to include the flags attribute
>>           * if we are setting the hw mode.
>>           */
> The comment above needs to be updated to reflect the new logic.

ok, will do, Thanks

>
>> -       if (mode >= 0) {
>> +       if (mode >= 0 || flags > 0) {
>>                  nest = addattr_nest(&req.n, sizeof(req), IFLA_AF_SPEC);
>>
>> -               addattr16(&req.n, sizeof(req), IFLA_BRIDGE_FLAGS, flags);
>> +               if (flags > 0)
>> +                       addattr16(&req.n, sizeof(req), IFLA_BRIDGE_FLAGS, flags);
>>
>>                  if (mode >= 0)
>>                          addattr16(&req.n, sizeof(req), IFLA_BRIDGE_MODE, mode);
>> --
>> 1.7.10.4
>>
> --
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