Messages in this thread Patch in this message | | | Date | Mon, 23 Jan 2012 15:41:06 -0800 | From | Greg KH <> | Subject | [20/27] [S390] fix cputime overflow in uptime_proc_show |
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2.6.32-longterm review patch. If anyone has any objections, please let me know.
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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
commit c3e0ef9a298e028a82ada28101ccd5cf64d209ee upstream.
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: Michael Abbott <michael.abbott@diamond.ac.uk> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/proc/uptime.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/fs/proc/uptime.c +++ b/fs/proc/uptime.c @@ -11,15 +11,20 @@ static int uptime_proc_show(struct seq_f { struct timespec uptime; struct timespec idle; + cputime64_t idletime; + u64 nsec; + u32 rem; int i; - cputime_t idletime = cputime_zero; + idletime = 0; for_each_possible_cpu(i) idletime = cputime64_add(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)),
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