Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:40031 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752270AbaABSzW (ORCPT ); Thu, 2 Jan 2014 13:55:22 -0500 Date: Thu, 2 Jan 2014 13:55:19 -0500 From: "J. Bruce Fields" To: NeilBrown Cc: Jeff Layton , Simo Sorce , linux-nfs@vger.kernel.org Subject: Re: should we change how the kernel detects whether gssproxy is running? Message-ID: <20140102185519.GL25684@fieldses.org> References: <20131231073300.0e0f220a@tlielax.poochiereds.net> <20131231180123.GA12875@fieldses.org> <20140101095620.0ab48051@notabene.brown> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20140101095620.0ab48051@notabene.brown> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Jan 01, 2014 at 09:56:20AM +1100, NeilBrown wrote: > On Tue, 31 Dec 2013 13:01:23 -0500 "J. Bruce Fields" > 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 :-) Yes, trying that myself, I see the delay reading kcore, a bunch of "file removed before we read it"/"file changed as we read it" errors (not too surprising), EBUSY on /proc/acpi/event, and a few permission errors. So yes letting a /proc read hang looks like a bug, my bad. --b.