On Mon, 16 Sep 2013, Fan Du wrote: > On 2013年09月13日 22:32, Thomas Gleixner wrote: > > On Fri, 13 Sep 2013, Fan Du wrote: > > > (2) What I have been bugging you around here for this long time is really > > > the > > > second > > > problem, I'm sorry I didn't make it clearly to you and others, which > > > is > > > below: > > > > > > Why using wall clock time to calculate soft/hard IPsec events when > > > xfrm_state timer > > > out happens in its timeout handler? Because even if xfrm_state using > > > CLOCK_BOOTTIME, > > > system wall clock time changing will surely disturb soft/hard IPsec > > > events, which > > > you raised your concern about in (*a*). > > > > No CLOCK_BOOTTIME is not affected by wall clock time changes. It's > > basically CLOCK_MONOTONIC, it just keeps counting the suspend time as > > well. So without a suspend/resume cycle CLOCK_MONOTONIC and > > CLOCK_BOOTTIME are the same. After a suspend/resume cycle > > CLOCK_BOOTTIME will be N seconds ahead of CLOCK_MONOTONIC, where N is > > the number of seconds spent in suspend. > > Sorry for the ambiguity. Yes, CLOCK_BOOTTIME is monotonic *and* counting > suspend/resume time as well as not affected by wall clock time change. > > Using CLOCK_BOOTTIME guarantees b- will timeout in a right manner, i.e., not > affected by wall clock time change, as well as keep the timer valid when > suspend/resume. > > A classic way of using timer is: > a- Arm a timer with specified interval > b- Wait for the timer to timeout > c- After the timeout, notify the event to other place in the timer handler. > > IPsec key lifetime timer does its this way: > a- Arm a timer with specified interval > b- Wait for the timer to timeout > c- After timeout, in the timer handler, using wall clock time to calculate > which kind of event to notify user(soft or hard for both key use time, > and key created time). So the problem arises at this stage if wall clock > time changed.
And why on earth must it use wall clock time for selecting the event type? Thanks, tglx