Date: Sun, 19 Feb 2012 21:52:19 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: David Xu <davidxu@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r231906 - head/lib/libthr/thread Message-ID: <20120219214118.G1461@besplex.bde.org> In-Reply-To: <201202190817.q1J8HEm1071390@svn.freebsd.org> References: <201202190817.q1J8HEm1071390@svn.freebsd.org>
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On Sun, 19 Feb 2012, David Xu wrote: > Log: > Check both seconds and nanoseconds are zero, only checking nanoseconds > is zero may trigger timeout too early. It seems a copy&paste bug. > > Modified: > head/lib/libthr/thread/thr_umtx.c > > Modified: head/lib/libthr/thread/thr_umtx.c > ============================================================================== > --- head/lib/libthr/thread/thr_umtx.c Sun Feb 19 07:44:38 2012 (r231905) > +++ head/lib/libthr/thread/thr_umtx.c Sun Feb 19 08:17:14 2012 (r231906) > @@ -205,7 +205,7 @@ _thr_umtx_timedwait_uint(volatile u_int > if (abstime != NULL) { > clock_gettime(clockid, &ts); > TIMESPEC_SUB(&ts2, abstime, &ts); > - if (ts2.tv_sec < 0 || ts2.tv_nsec <= 0) > + if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) > return (ETIMEDOUT); > tsp = &ts2; > } else { > Use timespeccmp()? It is even likely to be faster, since it can do the comparison in parallel, while the above has to wait for TIMESPEC_SUB() before doing the comparison, unless the compiler is very smart. However, I seem to have done too good a job of keeping kernel time* APIs out of userland, so timespeccmp() is only available in the kernel, and there are uglier but more correct unsafe macros like TIMESPEC_SUB() macros in userland, and various kernel APIs escaped anyway, starting with the NetBSD timeval ones, which escaped 10-15 years after timevals should have gone away because they were superseded by timespecs. Bruce
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