On Monday 11 June 2012 22:21:51 Hans Petter Selasky wrote:
> On Monday 11 June 2012 22:05:07 Pawel Jakub Dawidek wrote:
> > On Mon, Jun 11, 2012 at 07:21:00PM +0000, Hans Petter Selasky wrote:
> > > Author: hselasky
> > > Date: Mon Jun 11 19:20:59 2012
> > > New Revision: 236909
> > > URL: http://svn.freebsd.org/changeset/base/236909
> > >
> > > Log:
> > > Use the correct clock source when computing timeouts.
> >
> > Could you please explain why? As you can see some lines above in
>
> > cv_init(), we initialize condition variable with CLOCK_MONOTONIC too:
> Sorry, this was a mistake clearly. I will revert ASAP. Pointyhat to me.
>
> My test program didn't take the setattr into account.
>
> However, while at it, what is the default clock used by
> pthread_cond_timedwait(). In libusb we don't set any clock, and can we
> depend on that CLOCK_REALTIME is the default clock used? Else I should
> probably make a patch there.
>
> man pthread_cond_timedwait() is silent!
>
Hi,
Some more questions:
While doing my test, I traced pthread_cond_timedwait() into
"./kern/kern_umtx.c" where the time is subtracted again, so the actual time
value is not that important, but there are some other problems:
If the time structure argument passed to pthread_cond_timedwait() in 9-stable
is negative, for example the seconds field, the above mentioned function will
just return! See ./libkse/thread/thr_cond.c
int
_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
const struct timespec * abstime)
{
struct pthread *curthread = _get_curthread();
int rval = 0;
int done = 0;
int mutex_locked = 1;
int seqno;
THR_ASSERT(curthread->locklevel == 0,
"cv_timedwait: locklevel is not zero!");
if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
abstime->tv_nsec >= 1000000000)
return (EINVAL);
CLOCK_MONOTONIC: 18077 (seconds)
CLOCK_REALTIME: 1339451481 (seconds)
CLOCK_REALTIME will at some point become negative. Will libusb's timeout
functionality stop working then, because pthread_cond_timedwait() has a check
for negative time?
Or is hastd wrong, that it can compute a timeout offset which is outside the
valid range, because it uses a simple:
tv_sec += timeout?
tv_sec %= 1000000000; /* Is this perhaps missing in hastd and other drivers
???? */
What is the modulus which should be used for tv_sec?
--HPS
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