linux-kernel - Re: [PATCH 1/2] copy_process: fix CLONE_PARENT && ->exit

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Message-Id: <20090225193927.1ED25FC3DA@magilla.sf.frob.com>
Date:	Wed, 25 Feb 2009 11:39:27 -0800 (PST)
From:	Roland McGrath <roland@...hat.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Chris Evans <scarybeasts@...il.com>,
	David Howells <dhowells@...hat.com>,
	Don Howard <dhoward@...hat.com>,
	Eugene Teo <eugene@...hat.com>,
	Michael Kerrisk <mtk.manpages@...glemail.com>,
	Tavis Ormandy <taviso@....lonestar.org>,
	Vitaly Mayatskikh <vmayatsk@...hat.com>, stable@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] copy_process: fix CLONE_PARENT && ->exit_signal
	interaction

As I think I said before, I don't really know what the actual use case is
for CLONE_PARENT without CLONE_THREAD.  So it's easy to approve changing
its behavior, but I do vaguely worry about who expected what behavior before.

Just for readability, I would prefer that you just change the first line
above that sets p->exit_signal initially.  i.e. (but with some comments):

diff --git a/kernel/fork.c b/kernel/fork.c
index a66fbde..f56793b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1184,7 +1184,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	p->parent_exec_id = p->self_exec_id;
 
 	/* ok, now we should be set up.. */
-	p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
+	p->exit_signal = ((clone_flags & CLONE_THREAD) ? -1 :
+			  (clone_flags & CLONE_PARENT) ?
+			  current->group_leader->exit_signal :
+			  (clone_flags & CSIGNAL));
 	p->pdeath_signal = 0;
 	p->exit_state = 0;
 


Thanks,
Roland
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