On Wed, Jan 01, 2014 at 09:56:20AM +1100, NeilBrown wrote: > On Tue, 31 Dec 2013 13:01:23 -0500 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
