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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-02-27 16:35:50 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-03-07 12:54:22 +0300
commit814b8797f9863abc2877acf87f6be0f140d00139 (patch)
tree6532d58be3f811a5f173ccbb4e6eeed798baf797 /drivers/cpuidle
parentef8006846a3a97d9d8bf49e63dba948d0d2dbbf0 (diff)
downloadlinux-814b8797f9863abc2877acf87f6be0f140d00139.tar.xz
cpuidle: menu: Avoid overflows when computing variance
The variance computation in get_typical_interval() may overflow if the square of the value of diff exceeds the maximum for the int64_t data type value which basically is the case when it is of the order of UINT_MAX. However, data points so far in the future don't matter for idle state selection anyway, so change the initial threshold value in get_typical_interval() to INT_MAX which will cause more "outlying" data points to be discarded without affecting the selection result. Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/governors/menu.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 61316fc51548..5951604e7d5c 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -186,7 +186,7 @@ static unsigned int get_typical_interval(struct menu_device *data,
unsigned int min, max, thresh, avg;
uint64_t sum, variance;
- thresh = UINT_MAX; /* Discard outliers above this value */
+ thresh = INT_MAX; /* Discard outliers above this value */
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