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authorMichael Neuling <mikey@neuling.org>2007-11-19 23:18:40 -0500
committerPaul Mackerras <paulus@samba.org>2007-11-20 00:10:28 -0500
commit2b46b5673ca67d23302c2afac045def988a3cade (patch)
tree02b291c7d8fe862e2ac76b22a4fc361e4620f0a3 /arch/powerpc
parentc443acab2eebf12dce7e78fe29e76786f55ad1be (diff)
[POWERPC] Fix possible division by zero in scaled time accounting
If we get no user time and no system time allocated since the last account_system_vtime, the system to user time ratio estimate can end up dividing by zero. This was causing a problem noticed by Balbir Singh. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/time.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index c0d77723ba11..a925a8eae121 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -241,8 +241,9 @@ void account_system_vtime(struct task_struct *tsk)
241 /* deltascaled includes both user and system time. 241 /* deltascaled includes both user and system time.
242 * Hence scale it based on the purr ratio to estimate 242 * Hence scale it based on the purr ratio to estimate
243 * the system time */ 243 * the system time */
244 deltascaled = deltascaled * get_paca()->system_time / 244 if (get_paca()->user_time)
245 (get_paca()->system_time + get_paca()->user_time); 245 deltascaled = deltascaled * get_paca()->system_time /
246 (get_paca()->system_time + get_paca()->user_time);
246 delta += get_paca()->system_time; 247 delta += get_paca()->system_time;
247 get_paca()->system_time = 0; 248 get_paca()->system_time = 0;
248 } 249 }