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authorBalbir Singh <balbir@linux.vnet.ibm.com>2008-09-05 18:12:23 +0200
committerIngo Molnar <mingo@elte.hu>2008-09-05 18:14:35 +0200
commit49048622eae698e5c4ae61f7e71200f265ccc529 (patch)
treee568595fe5329e1293eafc3a3cc833dfe89ffbf2 /include
parent56c7426b3951e4f35a71d695f1c982989399d6fd (diff)
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 <balbir@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
-rw-r--r--include/linux/sched.h4
1 files changed, 4 insertions, 0 deletions
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
*/