Re: lockf in installworld -- not a good idea

On Fri, 29 Sep 2006, Pawel Jakub Dawidek wrote:

> On Fri, Sep 29, 2006 at 02:20:06PM +0100, Robert Watson wrote:
>> I've noticed an increasing intolerance in our tools for system install and maintenance to locking not being implemented over the past few years.  I no longer get working
>> cron on boxes with neither rpc.lockd nor local locking enabled, for
>> example. [...]
>
> If you are refering to my change in which cron(8) started to use pidfile(3), 
> then I'm sorry, but you're wrong.
>
> cron(8) from the very beginning was exiting when it had problems with 
> creating a pidfile, please check function acquire_daemonlock() in:

Cron may have been a poor example, I picked it from the top of a list of a 
half dozen failed services, many of which used not to fail.  Sorry about that.

> The way I prefer is to ignore errors other than EEXIST - you can check 
> EXAMPLES section in the pidfile(3) manual page for more info. I just didn't 
> wanted to change cron(8)'s original behaviour.
>
> I do agree, that this shouldn't be treated as critical error and I can 
> change it if you like.

I think if we get back EOPNOTSUPP from lock attempts in libpidfile, we should 
ignore it and hope for the best.  In an ideal world, we wouldn't do this, but 
in an ideal world we also wouldn't need to. :-)

Robert N M Watson
Computer Laboratory
University of Cambridge