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Date: Sun, 19 Feb 2012 19:00:20 +0800
From: David Xu <listlog2011@gmail.com>
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To: Bruce Evans <brde@optusnet.com.au>
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Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org,
	src-committers@FreeBSD.org, David Xu <davidxu@FreeBSD.org>
Subject: Re: svn commit: r231906 - head/lib/libthr/thread
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On 2012/2/19 18:52, Bruce Evans wrote:
> 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.
>
Yes

> 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 should have gone away because they were superseded by timespecs.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
>
Yes, we noticed that all timespec macros are not available for userland,
even TIMESPEC_SUB was copied from kernel.