From: Roland McGrath <roland@redhat.com>
To: arjanv@redhat.com
Cc: Linus Torvalds <torvalds@osdl.org>, Ingo Molnar <mingo@elte.hu>,
Petr Vandrovec <vandrove@vc.cvut.cz>,
Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@zip.com.au>
Subject: Re: [patch] Re: Problem with exiting threads under NPTL
Date: Mon, 15 Dec 2003 14:55:38 -0800 [thread overview]
Message-ID: <200312152255.hBFMtcEZ024917@magilla.sf.frob.com> (raw)
In-Reply-To: Arjan van de Ven's message of Monday, 15 December 2003 09:54:16 +0100 <1071478455.5223.0.camel@laptop.fenrus.com>
> On Sun, 2003-12-14 at 23:10, Linus Torvalds wrote:
>
> > Even though the parent ignores SIGCHLD it _can_ be running on another CPU
> > in "wait4()".
>
> which fwiw is a case of illegal behavior in the program ... of course
> the kernel shouldn't die if it happens.
No, it is legal to call wait* when ignoring SIGCHLD--and it is required to
return ECHILD for the dead ones. For example, using waitpid with WNOHANG
is a valid way to poll for the liveness of a child (though there is no good
reason why an application wouldn't just use kill(,0) for that). It's not a
method that has anything to recommend it, but it is perfectly valid and the
range of permissible results is well-specified.
next prev parent reply other threads:[~2003-12-15 22:55 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-14 5:25 Problem with exiting threads under NPTL Petr Vandrovec
2003-12-14 15:02 ` Martin Schlemmer
2003-12-14 19:38 ` [patch] " Ingo Molnar
2003-12-14 20:38 ` Linus Torvalds
2003-12-14 20:45 ` Linus Torvalds
2003-12-14 21:02 ` Ingo Molnar
2003-12-15 15:04 ` Jörn Engel
2003-12-14 21:06 ` Ingo Molnar
2003-12-14 22:10 ` Linus Torvalds
2003-12-14 22:17 ` Ingo Molnar
2003-12-14 22:32 ` Linus Torvalds
2003-12-15 23:04 ` Roland McGrath
2003-12-14 22:28 ` Ingo Molnar
2003-12-14 22:45 ` Linus Torvalds
2003-12-14 23:08 ` Ingo Molnar
2003-12-15 6:31 ` dan carpenter
2003-12-15 11:43 ` Ingo Molnar
2003-12-15 13:07 ` dan carpenter
2003-12-15 15:11 ` Linus Torvalds
2003-12-15 23:15 ` Roland McGrath
2003-12-15 8:54 ` Arjan van de Ven
2003-12-15 22:55 ` Roland McGrath [this message]
2003-12-15 23:06 ` Roland McGrath
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