[S390] fix cputime overflow in uptime_proc_show

For 32-bit architectures using standard jiffies the idletime calculation
in uptime_proc_show will quickly overflow. It takes (2^32 / HZ) seconds
of idle-time, or e.g. 12.45 days with no load on a quad-core with HZ=1000.
Switch to 64-bit calculations.

Cc: stable@vger.kernel.org
Cc: Michael Abbott <michael.abbott@diamond.ac.uk>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index ac5243657da3ca45d0f51e0ab7545c1094acf9fa..ab515109fec94457c75dfee50a1bdb5389c9198c 100644 (file)
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -11,15 +11,20 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 {
        struct timespec uptime;
        struct timespec idle;
+       cputime64_t idletime;
+       u64 nsec;
+       u32 rem;
        int i;
-       cputime_t idletime = 0;
 
+       idletime = 0;
        for_each_possible_cpu(i)
                idletime += kstat_cpu(i).cpustat.idle;
 
        do_posix_clock_monotonic_gettime(&uptime);
        monotonic_to_bootbased(&uptime);
-       cputime_to_timespec(idletime, &idle);
+       nsec = cputime64_to_jiffies64(idletime) * TICK_NSEC;
+       idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
+       idle.tv_nsec = rem;
        seq_printf(m, "%lu.%02lu %lu.%02lu\n",
                        (unsigned long) uptime.tv_sec,
                        (uptime.tv_nsec / (NSEC_PER_SEC / 100)),