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| author | Stanislaw Gruszka <sgruszka@redhat.com> | 2010-09-14 16:35:14 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-09-15 10:41:36 +0200 |
| commit | e75e863dd5c7d96b91ebbd241da5328fc38a78cc (patch) | |
| tree | b7b67512b6b610c8ee90149c9b48dbaeeb1e4910 /kernel | |
| parent | 9c03f1622af051004416dd3e24d8a0fa31e34178 (diff) | |
| download | lwn-e75e863dd5c7d96b91ebbd241da5328fc38a78cc.tar.gz lwn-e75e863dd5c7d96b91ebbd241da5328fc38a78cc.zip | |
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. When the
overflow happens then the scaled utime value becomes erroneously
small and the scaled stime becomes i erroneously 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>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: <stable@kernel.org> # 2.6.32.19+ (partially) and 2.6.33+
LKML-Reference: <20100914143513.GB8415@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index ed09d4f2a69c..dc85ceb90832 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3513,9 +3513,9 @@ 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 @@ -3546,9 +3546,9 @@ 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 |