Timing bug somewhere-or-other

[ewx]

richard@araminta:~$ cat t.c
#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <assert.h>
int main(void) {
  for(;;) {
    time_t t;
    struct timeval tv;

    assert(gettimeofday(&tv, NULL) == 0);
    assert(time(&t) != (time_t)-1);
    if(t < tv.tv_sec)
      return printf("%ld %ld.%06ld\n", t, tv.tv_sec, tv.tv_usec);
  }
}

richard@araminta:~$ gcc -o t t.c
richard@araminta:~$ ./t
1255784018 1255784019.000000

richard@araminta:~$ uname -a
Linux araminta 2.6.26-2-xen-amd64 #1 SMP Thu Aug 20 00:36:34 UTC 2009 x86_64 GNU/Linux
richard@araminta:~$ dpkg -l libc6\*|grep ^i
ii  libc6                                   2.7-18                     GNU C Library: Shared libraries
ii  libc6-dbg                               2.7-18                     GNU C Library: Libraries with debugging symb
ii  libc6-dev                               2.7-18                     GNU C Library: Development Libraries and Hea
ii  libc6-dev-i386                          2.7-18                     GNU C Library: 32bit development libraries f
ii  libc6-i386                              2.7-18                     GNU C Library: 32bit shared libraries for AM
ii  libc6-prof                              2.7-18                     GNU C Library: Profiling Libraries
richard@araminta:~$ cat /proc/cpuinfo 
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 15
model name	: Intel(R) Core(TM)2 Quad CPU    Q6600  @ 2.40GHz
stepping	: 11
cpu MHz		: 2397.654
cache size	: 4096 KB
physical id	: 0
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 10
wp		: yes
flags		: fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good pni ssse3 cx16 lahf_lm
bogomips	: 4801.28
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:
<etc etc etc>

Comments

[ewx.livejournal.com]

I don't see it under Debian's 2.6.18 (in a Xen guest). So I think you're right about it being introduced later.

[ewx.livejournal.com]

...but 2.6.24 has the bug.