Re: CVS commit: src/sys/net

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

On Fri, Sep 22, 2017 at 5:53 PM, Joerg Sonnenberger <joerg%bec.de@localhost> wrote:
> On Fri, Sep 22, 2017 at 05:05:32AM +0000, Ryota Ozaki wrote:
>> Module Name:  src
>> Committed By: ozaki-r
>> Date:         Fri Sep 22 05:05:32 UTC 2017
>>
>> Modified Files:
>>       src/sys/net: route.c
>>
>> Log Message:
>> Remove the global lock for rtcache
>>
>> Thanks to removal of LIST_ENTRY of struct route, rtcaches are accessed only by
>> their users. And in existing usages a rtcache is guranteed to be not accessed
>> simultaneously. So the rtcache framework doesn't need any exclusion controls
>> in itself.
>
> I'm a bit suspicous about this since the generation counter is not
> atomic. So what guarantees that route manipulations of different
> subsystems don't race?

If !NET_MPSAFE, it's softnet_lock, however, if NET_MPSAFE, nothing guarantees
that as you suspect. I've fixed the issue. Thanks!

  ozaki-r