linux-kernel - Re: [Bugme-new] [Bug 9906] New: Weird hang with NPTL and SIGPROF.

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Date:	Fri, 07 Mar 2008 16:01:37 -0800
From:	Frank Mayhar <fmayhar@...gle.com>
To:	Roland McGrath <roland@...hat.com>
Cc:	parag.warudkar@...il.com,
	Alejandro Riveira Fernández 
	<ariveira@...il.com>, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jakub Jelinek <jakub@...hat.com>
Subject: Re: [Bugme-new] [Bug 9906] New: Weird hang with NPTL and SIGPROF.

On Fri, 2008-03-07 at 15:26 -0800, Frank Mayhar wrote:
> Based on Roland's comments and from reading the source, I have a
> possible fix.  I'm posting the attached patch _not_ for submission but
> _only_ for comment.  For one thing it's based on 2.6.18.5 and for
> another it hasn't had much testing yet.  I wanted to get it out here for
> comment, though, in case anyone can see where I might have gone wrong.
> Comments, criticism and (especially!) testing enthusiastically
> requested.

The previous email was missing one small part of the patch, reproduced
below.  Remain calm.
----------------------------------BEGIN------------------------------------
diff -urp /home/fmayhar/Static/linux-2.6.18.5/kernel/compat.c linux-2.6.18.5/kernel/compat.c
--- /home/fmayhar/Static/linux-2.6.18.5/kernel/compat.c	2006-12-01 16:13:05.000000000 -0800
+++ linux-2.6.18.5/kernel/compat.c	2008-03-06 17:26:21.000000000 -0800
@@ -161,18 +161,11 @@ asmlinkage long compat_sys_times(struct 
 	if (tbuf) {
 		struct compat_tms tmp;
 		struct task_struct *tsk = current;
-		struct task_struct *t;
 		cputime_t utime, stime, cutime, cstime;
 
 		read_lock(&tasklist_lock);
-		utime = tsk->signal->utime;
-		stime = tsk->signal->stime;
-		t = tsk;
-		do {
-			utime = cputime_add(utime, t->utime);
-			stime = cputime_add(stime, t->stime);
-			t = next_thread(t);
-		} while (t != tsk);
+		utime = tsk->signal->shared_utime;
+		stime = tsk->signal->shared_stime;
 
 		/*
 		 * While we have tasklist_lock read-locked, no dying thread
-----------------------------------END-------------------------------------
-- 
Frank Mayhar <fmayhar@...gle.com>
Google, Inc.

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