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From: Paul Smith <psmith@gnu.org>
To: David Laight <David.Laight@ACULAB.COM>,
	'Linus Torvalds' <torvalds@linux-foundation.org>
Cc: 'Arnd Bergmann' <arnd@arndb.de>,
	'Masahiro Yamada' <yamada.masahiro@socionext.com>,
	'Linux Kernel Mailing List' <linux-kernel@vger.kernel.org>
Subject: Re: I disabled more compiler warnings..
Date: Wed, 13 May 2020 12:06:45 -0400	[thread overview]
Message-ID: <5cb62c1a8ca38a3eceb37f7d236828761cad07ce.camel@gnu.org> (raw)
In-Reply-To: <b206fa1343b94f768ce0d57f0234c8e7@AcuMS.aculab.com>

On Wed, 2020-05-13 at 15:53 +0000, David Laight wrote:
> > If we don't have pselect() we use the close() in the signal
> > handler. In that case we're just waiting in the read(), we're not
> > using select() or poll() or whatever.  It's definitely the case
> > that if we're waiting in read() and someone closes the FD, we'll
> > wake up! :)
> 
> Ugg, that is relying on getting either EINTR or EBADFD.

Yes, exactly.

> I can't remember if Posix allows SIGCHLD to be delivered
> in a different thread.

It does: all you have to do is ensure that all threads other than the
one you want block the signal.

However, GNU make is not multithreaded so this is moot.

> Windows definitely likes delivering signals that way :-)

In Windows IIRC GNU make doesn't use this method at all; Windows has
some kind of process shared semaphore that is used instead.  I didn't
write that code so I can't really describe it in detail :)


  reply	other threads:[~2020-05-13 16:06 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-10 19:33 Linus Torvalds
2020-05-11  7:43 ` David Laight
2020-05-11 17:41   ` Linus Torvalds
2020-05-11 17:58     ` Paul Smith
2020-05-11 19:33       ` Linus Torvalds
2020-05-11 20:25         ` Paul Smith
2020-05-11 21:09       ` David Laight
2020-05-12  7:55         ` David Laight
2020-05-12 14:35           ` Paul Smith
2020-05-12 15:04             ` David Laight
2020-05-12 16:55               ` Paul Smith
2020-05-13  8:21                 ` David Laight
2020-05-13 15:32                   ` Paul Smith
2020-05-13 15:53                     ` David Laight
2020-05-13 16:06                       ` Paul Smith [this message]
2020-05-11  9:03 ` Arnd Bergmann
2020-05-11 11:11   ` Arnd Bergmann

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