On Mon, Oct 10, 2016 at 11:09:35AM +0200, Victor Tapia wrote: > El 10/10/16 a las 10:56, Ian Kent escribió: > > On Mon, 2016-10-10 at 10:42 +0200, Jakub Hrozek wrote: > >> On Mon, Oct 10, 2016 at 10:04:30AM +0200, Victor Tapia wrote: > >>> Hi list, > >>> > >>> I've faced a race condition when SSSD boots in a machine with a big > >>> clock drift. This is what I see: > >>> > >>> 1. SSSD starts before the network is up, queries the LDAP server without > >>> success and sets a retry timer (~60 secs) > >>> 2. NTP starts and corrects the clock, 1 hour back for example. > >>> 3. SSSD takes ~60 secs + the drift correction (1 hour) to retry the > >>> connection. > >>> > >>> In this particular scenario the credentials cache is disabled, so the > >>> wait time to login is noticeable. How feasible would it be to use a > >>> monotonic clock for this kind of timed events? > >> > >> I really have not tried this and I guess I don't know tevent internals > >> well enough if this works, but I wonder if just using: > >> clock_getime() > > > > With a CLOCK_MONOTONIC I presume? > > I think that's what has been suggested. > > > > I was thinking about using CLOCK_MONOTONIC_RAW: > > CLOCK_MONOTONIC_RAW (since Linux 2.6.28; Linux-specific) > Similar to CLOCK_MONOTONIC, but provides access to a raw hardware-based > time that is not subject to NTP adjustments or the incremental > adjustments performed by adjtime(3). > > >> and constructing struct timeval > >> in place of: > >> tevent_timeval_current_ofs() > >> could solve this particular issue. > >> > >> On the other hand, this is a pattern we use in SSSD all through the code > >> for timed events and we're just not well equipped to handle time drifts. > >> Did you investigate why doesn't sssd detect the networking change from > >> libnl messages or from resolv.conf being touched? > > I didn't dig much into it yet (I just checked tevent to confirm it uses > gettimeofday()), so I'll take this as my next step.
btw the samba-technical mailing list is the best source of info about libtevent and the best place to ask questions about libtevent.. _______________________________________________ sssd-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
