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Date: Wed, 09 Jan 2013 11:22:53 +0800
From: David Xu <davidxu@freebsd.org>
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To: Daniel Eischen <deischen@freebsd.org>
Subject: Re: Is it possible to block pending queued RealTime signals (AIO
 originating)?
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Cc: freebsd-hackers@freebsd.org, Richard Sharpe <rsharpe@richardsharpe.com>
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On 2013/01/09 11:14, Daniel Eischen wrote:
> On Tue, 8 Jan 2013, Richard Sharpe wrote:
>
>> [ ... ]
>>
>> Well, it turns out that your suggestion was correct.
>>
>> I did some more searching and found another similar suggestion, so I
>> gave it a whirl, and it works.
>>
>> Now, my problem is that Jeremy Allison thinks that it is a fugly hack.
>> This means that I will probably have big problems getting a patch for
>> this into Samba.
>
> I don't understand why JA thinks this is a hack.  Their current
> method doesn't work, or at least isn't portable.  I've tried this
> on Solaris 10, and it works just as it does in FreeBSD.  Test
> program included after signature.
>
>    $ ./test_sigprocmask
>    Sending signal 16
>    Got signal 16, blocked: true
>    Blocking signal 16 using method 0
>    Handled signal 16, blocked: false
>
>    Sending signal 16
>    Got signal 16, blocked: true
>    Blocking signal 16 using method 1
>    Handled signal 16, blocked: true
>

Yeah, people think that signal handler is normal code, this is a
misunderstanding, in fact, it really works like an interrupt service 
routine.