On Thu, Dec 20, 2012 at 11:22:02AM +0100, Jean Delvare wrote: > Hi Guenter, > > On Wed, 19 Dec 2012 14:41:22 -0800, Guenter Roeck wrote: > > On Wed, Dec 19, 2012 at 01:47:21PM -0800, Andrew Morton wrote: > > > The changelog didn't describe the end-user visible effects of the bug. > > > Please always include this information. Because... > > > > One observed effect is that the s2c_hwmon driver reports a value of 4198403 > > instead of 0 if the ADC reads 0. > > > > Other impact is unpredictable. Problem is seen if the divisor is an unsigned > > variable or constant and the dividend is less than (divisor/2). > > Really? In my own testing, the problem only shows with dividend == 0, and even > then, only when dividend is signed and divisor is not. DIV_ROUND_CLOSEST(5, > 20U) returns 0 as expected, and so do DIV_ROUND_CLOSEST(0 / 20), > DIV_ROUND_CLOSEST(0U / 20) and DIV_ROUND_CLOSEST(0U / 20U). > > Are your observations different? > Hmm, you are right - it only happens with 0. I thought I had also seen it with other values. > > > The patch is applicable to 3.7.x. Should we backport it? > > > > Yes. DIV_ROUND_CLOSEST is used throughout the kernel, and impact is > > unpredictable. > > > > 3.6 needs it as well. > Turns out 3.6 is EOL, so we'll only need it in 3.7. Guenter _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
