On Tue, Jul 23, 2019 at 04:11:09PM +0800, Yang Xu wrote: > > 2) according to man page passing negative value should be acceptable, > > though it never worked as expected. I've been grepping "git log" > > for this file and the former API is coming from > > > > commit 6976675d94042fbd446231d1bd8b7de71a980ada > > Author: Arjan van de Ven<[email protected]> > > Date: Mon Sep 1 15:52:40 2008 -0700 > > > > hrtimer: create a "timer_slack" field in the task struct > > > > which is 11 years old by now. Nobody complained so far even when man > > page is saying pretty obviously > > > > PR_SET_TIMERSLACK (since Linux 2.6.28) > > Each thread has two associated timer slack values: a > > "default" > > value, and a "current" value. This operation sets the > > "current" > > timer slack value for the calling thread. If the > > nanosecond > > value supplied in arg2 is greater than zero, then the > > "current" > > value is set to this value. If arg2 is less than or equal > > to > > zero, the "current" timer slack is reset to the > > thread's > > "default" timer slack value. > > > > So i think to match the man page (and assuming that accepting negative value > > has been supposed) we should rather do > > > > if ((long)arg2< 0) > Looks correct. But if we set a ULONG_MAX(PR_GET_TIMERSLACK also limits > ULONG_MAX) > value(about 4s) on 32bit machine, this code will think this value is a > negative value and use default value. > > I guess man page was written as "less than or equal to zero" because of this > confusing code(arg2<=0, but arg2 > is an unsinged long value). > I think we can change this man page and also add bounds value description.
OK, seems reasonable. I think we should use comparision with zero and simply update a man page.
