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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-02-27 14:35:50 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-03-07 10:54:22 +0100 |
| commit | 814b8797f9863abc2877acf87f6be0f140d00139 (patch) | |
| tree | 6532d58be3f811a5f173ccbb4e6eeed798baf797 /drivers/cpuidle | |
| parent | ef8006846a3a97d9d8bf49e63dba948d0d2dbbf0 (diff) | |
| download | lwn-814b8797f9863abc2877acf87f6be0f140d00139.tar.gz lwn-814b8797f9863abc2877acf87f6be0f140d00139.zip | |
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.c | 2 |
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 */ again: |