Re: should we change how the kernel detects whether gssproxy is running?

[NeilBrown <neilb@suse.de>]

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On Tue, 31 Dec 2013 13:01:23 -0500 "J. Bruce Fields" <bfields@fieldses.org>
wrote:

> On Tue, Dec 31, 2013 at 07:33:00AM -0500, Jeff Layton wrote:
> > I'm a bit concerned with how /proc/net/rpc/use-gss-proxy works...
> > 
> > For one thing, when the kernel first boots any read against that file
> > hangs. That's going to be extremely problematic for certain tools that
> > scrape info out of /proc for troubleshooting purposes (e.g. Red Hat's
> > sosreport tool).
> 
> Is that the only file under /proc for which that's true?  (E.g. the rpc
> cache channel files probably do the same, don't they?)  I was assuming
> tools like sosreport need to work from lists of specific paths.

The rpc cache channel files do not block on reads, so 'cat' works well on
them.
A process (like mountd) that wasn't to see new additions will use select (or
poll) for an 'exception' condition, and then read.

I think that it is best of all files in /proc (or /sys) would support 'cat'.
If I "tar" up "/proc" on my notebook it doesn't block ... though it does take
quite a while on /proc/kcore :-)

NeilBrown

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