Re: RFC: too aggressive nanosleep replacement on 64 bit Linux?

[Paul Eggert]

[CC'ing Thomas Gleixner, who maintains the Linux kernel's POSIX clocks 
and timers.  Thomas, this thread started at 
<http://lists.gnu.org/archive/html/bug-gnulib/2014-08/msg00005.html>.]

Pádraig Brady wrote:
> I noticed that nanosleep() was replaced on 64 bit Linux ...
> Should we be more conservative with our replacement, and be happy with 292 
> years?

It'd be nicer to get the kernel bug fixed (eventually it's bound to 
break something when the kernel is off by 293 billion years :-).

I'm attaching a program that illustrates the bug on Fedora 20 (kernel 
3.15.7-200.fc20.x86_64) and on Ubuntu 14.04.1 (kernel 3.13.0-32-generic 
#57-Ubuntu x86-64).  Running this program on a buggy host outputs 
something like this:

Setting alarm for 1 second from now ...
Sleeping for 9223372036854775807.999999999 seconds...
After alarm sent off, remaining time is 9223357678.462306617 seconds;
i.e., nanosleep claimed that it slept for about 293079448610.606445 years.

and the program exits with status 4.  Gnulib-using applications have a 
workaround for this bug, but a workaround shouldn't be necessary.  For 
what it's worth, the bug is fixed in Solaris 11 (x86-64), though it's 
present in Solaris 10 (64-bit sparc).

Thomas, are you the right person to get it fixed in the Linux kernel, or 
should I email a bug report somewhere else?  Thanks.

nanosleep-bug.c
Description: Text Data