Re: [xen-unstable test] 13461: regressions - FAIL

[Roger Pau Monne <roger.pau@citrix.com>]

Ian Jackson wrote:
> Ian Campbell writes ("Re: [Xen-devel] [xen-unstable test] 13461: regressions - FAIL"):
>>> +        flock -x $_lockfd
>>> +        # We can't just stat /dev/stdin or /proc/self/fd/$_lockfd or
>>> +        # use bash's test -ef because those all go through what is
>>> +        # actually a synthetic symlink in /proc and we aren't
>>> +        # guaranteed that our stat(2) won't lose the race with an
>>> +        # rm(1) between reading the synthetic link and traversing the
>>> +        # file system to find the inum.  Perl is very fast so use that.
>>> +        rightfile=$( perl -e '
>> Won't this need to become $(PERL) (or @PERL@ and some seddery at install
>> time) for the benefit of BSD?
>
> This is in tools/hotplug/Linux.  AFAICT at least some of the BSDs have
> an fstat(1).

BSD don't currently have any of this locking mechanism, which makes it 
vulnerable to races regarding hotplug scripts launch. I think libxl 
should be a better place to perform all this kind of locking, instead of 
the hotplug scripts, which are already polluted enough, but as far as I 
know we don't have any kind of inter-process locking mechanism right now?