From 49048622eae698e5c4ae61f7e71200f265ccc529 Mon Sep 17 00:00:00 2001 From: Balbir Singh Date: Fri, 5 Sep 2008 18:12:23 +0200 Subject: sched: fix process time monotonicity Spencer reported a problem where utime and stime were going negative despite the fixes in commit b27f03d4bdc145a09fb7b0c0e004b29f1ee555fa. The suspected reason for the problem is that signal_struct maintains it's own utime and stime (of exited tasks), these are not updated using the new task_utime() routine, hence sig->utime can go backwards and cause the same problem to occur (sig->utime, adds tsk->utime and not task_utime()). This patch fixes the problem TODO: using max(task->prev_utime, derived utime) works for now, but a more generic solution is to implement cputime_max() and use the cputime_gt() function for comparison. Reported-by: spencer@bluehost.com Signed-off-by: Balbir Singh Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- include/linux/sched.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/sched.h b/include/linux/sched.h index cfb0d87b99f..3d9120c5ad1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1475,6 +1475,10 @@ static inline void put_task_struct(struct task_struct *t) __put_task_struct(t); } +extern cputime_t task_utime(struct task_struct *p); +extern cputime_t task_stime(struct task_struct *p); +extern cputime_t task_gtime(struct task_struct *p); + /* * Per process flags */ -- cgit v1.2.3-70-g09d2