lkml.org 
[lkml]   [2010]   [Sep]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH v2] sched: fix user time incorrectly accounted as system time on 32 bit
    We have 32 bit variable overflow possibility when multiply in
    task_times() and thread_group_times() functions. If overflow happens
    calculated scaled utime value become wrongly small and scaled stime
    wrongly big.

    Reported here:
    https://bugzilla.redhat.com/show_bug.cgi?id=633037
    https://bugzilla.kernel.org/show_bug.cgi?id=16559

    Reported-by: Michael Chapman <redhat-bugzilla@very.puzzling.org>
    Reported-by: Ciriaco Garcia de Celis <sysman@etherpilot.com>
    Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: <stable@kernel.org> # 2.6.32.19+ (partially) and 2.6.33+
    Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
    ---
    v1 -> v2
    Fix mail recipients.

    kernel/sched.c | 8 ++++----
    1 files changed, 4 insertions(+), 4 deletions(-)

    diff --git a/kernel/sched.c b/kernel/sched.c
    index 09b574e..eee9470 100644
    --- a/kernel/sched.c
    +++ b/kernel/sched.c
    @@ -3507,9 +3507,9 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
    rtime = nsecs_to_cputime(p->se.sum_exec_runtime);

    if (total) {
    - u64 temp;
    + u64 temp = rtime;

    - temp = (u64)(rtime * utime);
    + temp *= utime;
    do_div(temp, total);
    utime = (cputime_t)temp;
    } else
    @@ -3540,9 +3540,9 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
    rtime = nsecs_to_cputime(cputime.sum_exec_runtime);

    if (total) {
    - u64 temp;
    + u64 temp = rtime;

    - temp = (u64)(rtime * cputime.utime);
    + temp *= cputime.utime;
    do_div(temp, total);
    utime = (cputime_t)temp;
    } else
    --
    1.7.1


    \
     
     \ /
      Last update: 2010-09-14 16:37    [W:0.026 / U:30.428 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site