Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | [PATCH] cpuidle: menu: Avoid overflows when computing variance | Date | Wed, 27 Feb 2019 14:35:50 +0100 |
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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> --- drivers/cpuidle/governors/menu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-pm/drivers/cpuidle/governors/menu.c =================================================================== --- linux-pm.orig/drivers/cpuidle/governors/menu.c +++ linux-pm/drivers/cpuidle/governors/menu.c @@ -186,7 +186,7 @@ static unsigned int get_typical_interval 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:
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