From: Roland McGrath <roland@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linus Torvalds <torvalds@transmeta.com>,
Anton Blanchard <anton@samba.org>, Andrew Morton <akpm@digeo.com>,
Arjan van de Ven <arjanv@redhat.com>,
<linux-kernel@vger.kernel.org>
Subject: Re: heavy handed exit() in latest BK
Date: Sun, 9 Feb 2003 03:56:50 -0800 [thread overview]
Message-ID: <200302091156.h19BuoH07869@magilla.sf.frob.com> (raw)
In-Reply-To: Ingo Molnar's message of Sunday, 9 February 2003 12:40:32 +0100 <Pine.LNX.4.44.0302091236590.4454-100000@localhost.localdomain>
> - a read_lock(&tasklist_lock) is missing around the group_send_sig_info()
> in send_sig_info().
Indeed. I still intend to clean up those entry points and haven't gotten
to it, so I hadn't bothered with this yet either (though I think I sent it
to you for the backport). It certainly does bite in practice, e.g. SIGPIPE.
There is a similar failure to take the lock before using zap_other_threads.
I thought I sent this patch before, but it's not in 2.5 yet.
--- /home/roland/redhat/linux-2.5.59-1.1007/fs/exec.c.~1~ Fri Feb 7 20:04:27 2003
+++ /home/roland/redhat/linux-2.5.59-1.1007/fs/exec.c Sun Feb 9 03:43:36 2003
@@ -601,9 +601,12 @@ static inline int de_thread(struct task_
if (thread_group_empty(current))
goto no_thread_group;
+
/*
- * Kill all other threads in the thread group:
+ * Kill all other threads in the thread group.
+ * We must hold tasklist_lock to call zap_other_threads.
*/
+ read_lock(&tasklist_lock);
spin_lock_irq(lock);
if (oldsig->group_exit) {
/*
@@ -611,6 +614,7 @@ static inline int de_thread(struct task_
* return so that the signal is processed.
*/
spin_unlock_irq(lock);
+ read_unlock(&tasklist_lock);
kmem_cache_free(sighand_cachep, newsighand);
if (newsig)
kmem_cache_free(signal_cachep, newsig);
@@ -629,12 +633,15 @@ static inline int de_thread(struct task_
oldsig->group_exit_task = current;
current->state = TASK_UNINTERRUPTIBLE;
spin_unlock_irq(lock);
+ read_unlock(&tasklist_lock);
schedule();
+ read_lock(&tasklist_lock);
spin_lock_irq(lock);
if (oldsig->group_exit_task)
BUG();
}
spin_unlock_irq(lock);
+ read_unlock(&tasklist_lock);
/*
* At this point all other threads have exited, all we have to
> - session-IDs and group-IDs are set outside the tasklist lock. This
> causes breakage in the USB code. The correct fix is to do this:
This is outside the part of the code that I've touched lately.
Thanks,
Roland
next prev parent reply other threads:[~2003-02-09 11:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200302091130.h19BU2107744@magilla.sf.frob.com>
2003-02-09 11:40 ` heavy handed exit() in latest BK Ingo Molnar
2003-02-09 11:56 ` Roland McGrath [this message]
2003-02-09 12:09 ` Ingo Molnar
2003-02-09 12:18 ` Ingo Molnar
2003-02-09 12:23 ` Ingo Molnar
2003-02-09 12:22 ` Arjan van de Ven
2003-02-10 1:07 ` Linus Torvalds
2003-02-10 1:27 ` Roland McGrath
2003-02-09 0:57 Anton Blanchard
2003-02-09 2:00 ` Linus Torvalds
2003-02-09 2:17 ` Roland McGrath
2003-02-09 2:19 ` Linus Torvalds
2003-02-09 2:31 ` Roland McGrath
2003-02-09 2:34 ` Linus Torvalds
2003-02-09 2:33 ` Linus Torvalds
2003-02-09 2:41 ` Roland McGrath
2003-02-09 3:30 ` Roland McGrath
2003-02-09 3:33 ` Roland McGrath
2003-02-09 3:37 ` Linus Torvalds
2003-02-09 3:40 ` Linus Torvalds
2003-02-09 3:48 ` Roland McGrath
2003-02-09 4:51 ` Linus Torvalds
2003-02-09 4:57 ` Linus Torvalds
2003-02-09 5:00 ` Roland McGrath
2003-02-09 9:28 ` Russell King
2003-02-10 8:53 ` Ingo Molnar
2003-02-10 15:22 ` Linus Torvalds
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