From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Dipankar Sarma <dipankar@in.ibm.com>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Oleg Nesterov <oleg@tv-sign.ru>,
Al Viro <viro@zeniv.linux.org.uk>,
James Morris <jmorris@namei.org>,
David Howells <dhowells@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>
Subject: [patch 7/9] signals: Fix more rcu assumptions
Date: Thu, 10 Dec 2009 00:53:21 -0000 [thread overview]
Message-ID: <20091210004703.269843657@linutronix.de> (raw)
In-Reply-To: 20091210001308.247025548@linutronix.de
[-- Attachment #1: signal-fix-more-rcu-assumptions.patch --]
[-- Type: text/plain, Size: 1830 bytes --]
1) Remove the misleading comment in __sigqueue_alloc() which claims
that holding a spinlock is equivalent to rcu_read_lock().
2) Wrap the __send_signal() call in send_signal() into a rcu read side
critical section to guarantee that the __sigqueue_alloc()
requirement is met in any case.
This needs to be revisited to remove the remaining users of
read_lock(&tasklist_lock) but that's outside the scope of this patch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
---
kernel/signal.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
Index: linux-2.6-tip/kernel/signal.c
===================================================================
--- linux-2.6-tip.orig/kernel/signal.c
+++ linux-2.6-tip/kernel/signal.c
@@ -220,8 +220,7 @@ __sigqueue_alloc(int sig, struct task_st
/*
* We won't get problems with the target's UID changing under us
* because changing it requires RCU be used, and if t != current, the
- * caller must be holding the RCU readlock (by way of a spinlock) and
- * we use RCU protection here
+ * caller must be holding the RCU readlock.
*/
user = get_uid(__task_cred(t)->user);
atomic_inc(&user->sigpending);
@@ -946,7 +945,7 @@ out_set:
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
int group)
{
- int from_ancestor_ns = 0;
+ int ret, from_ancestor_ns = 0;
#ifdef CONFIG_PID_NS
if (!is_si_special(info) && SI_FROMUSER(info) &&
@@ -954,7 +953,11 @@ static int send_signal(int sig, struct s
from_ancestor_ns = 1;
#endif
- return __send_signal(sig, info, t, group, from_ancestor_ns);
+ rcu_read_lock();
+ ret = __send_signal(sig, info, t, group, from_ancestor_ns);
+ rcu_read_unlock();
+
+ return ret;
}
static void print_fatal_signal(struct pt_regs *regs, int signr)
next prev parent reply other threads:[~2009-12-10 0:54 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-10 0:52 [patch 0/9] Fix various __task_cred related invalid RCU assumptions Thomas Gleixner
2009-12-10 0:52 ` [patch 1/9] sys: Fix missing rcu protection for __task_cred() access Thomas Gleixner
2009-12-10 1:25 ` Paul E. McKenney
2009-12-10 2:29 ` Tetsuo Handa
2009-12-10 2:43 ` Paul E. McKenney
2009-12-10 14:29 ` Oleg Nesterov
2009-12-10 14:44 ` Thomas Gleixner
2009-12-11 13:45 ` David Howells
2009-12-11 13:52 ` Thomas Gleixner
2009-12-10 14:20 ` Oleg Nesterov
2009-12-10 14:38 ` Thomas Gleixner
2009-12-10 15:08 ` [patch 1/9] sys: Fix missing rcu protection for __task_cred()access Tetsuo Handa
2009-12-10 21:17 ` Thomas Gleixner
2009-12-11 3:25 ` Tetsuo Handa
2010-02-08 12:30 ` [PATCH] Update comment on find_task_by_pid_ns Tetsuo Handa
2010-02-08 13:21 ` Oleg Nesterov
2010-02-08 17:07 ` Thomas Gleixner
2010-02-08 17:16 ` Oleg Nesterov
2010-02-08 21:42 ` Tetsuo Handa
2010-02-09 22:08 ` Andrew Morton
2010-02-10 16:30 ` Serge E. Hallyn
2010-02-10 17:57 ` Andrew Morton
2010-02-10 18:39 ` Thomas Gleixner
2010-02-10 20:18 ` Serge E. Hallyn
2010-02-10 20:30 ` Paul E. McKenney
2010-02-11 1:21 ` Tetsuo Handa
2010-02-11 12:04 ` [PATCH] sys: Fix missing rcu protection for sys_getpriority Tetsuo Handa
2010-02-12 14:22 ` Serge E. Hallyn
2009-12-10 22:09 ` [tip:core/urgent] sys: Fix missing rcu protection for __task_cred() access tip-bot for Thomas Gleixner
2009-12-10 0:52 ` [patch 2/9] fs: Add missing rcu protection for __task_cred() in sys_ioprio_get Thomas Gleixner
2009-12-10 0:53 ` [patch 3/9] proc: Add missing rcu protection for __task_cred() in task_sig() Thomas Gleixner
2009-12-10 0:53 ` [patch 4/9] oom: Add missing rcu protection of __task_cred() in dump_tasks Thomas Gleixner
2009-12-10 1:57 ` KOSAKI Motohiro
2009-12-10 0:53 ` [patch 5/9] security: Use get_task_cred() in keyctl_session_to_parent() Thomas Gleixner
2009-12-10 2:45 ` Paul E. McKenney
2009-12-10 0:53 ` [patch 6/9] signal: Fix racy access to __task_cred in kill_pid_info_as_uid() Thomas Gleixner
2009-12-10 15:11 ` Oleg Nesterov
2009-12-10 22:09 ` [tip:core/urgent] " tip-bot for Thomas Gleixner
2009-12-10 0:53 ` Thomas Gleixner [this message]
2009-12-10 14:34 ` [patch 7/9] signals: Fix more rcu assumptions Oleg Nesterov
2009-12-10 14:45 ` Thomas Gleixner
2009-12-11 13:59 ` David Howells
2009-12-10 22:09 ` [tip:core/urgent] " tip-bot for Thomas Gleixner
2009-12-10 0:53 ` [patch 8/9] Documentation: Fix invalid " Thomas Gleixner
2009-12-10 23:55 ` Vegard Nossum
2009-12-11 21:28 ` Arnd Bergmann
2009-12-11 22:01 ` Paul E. McKenney
2009-12-10 0:53 ` [patch 9/9] security: Fix invalid rcu assumptions in comments Thomas Gleixner
2009-12-10 2:28 ` [patch 0/9] Fix various __task_cred related invalid RCU assumptions Paul E. McKenney
2009-12-10 3:15 ` Linus Torvalds
2009-12-10 5:13 ` Peter Zijlstra
2009-12-10 5:34 ` Paul E. McKenney
2009-12-13 18:56 ` Peter Zijlstra
2009-12-14 1:53 ` Paul E. McKenney
2009-12-14 10:17 ` Peter Zijlstra
2009-12-14 14:16 ` Paul E. McKenney
2009-12-14 14:30 ` Peter Zijlstra
2009-12-15 1:23 ` Paul E. McKenney
2009-12-11 13:39 ` David Howells
2009-12-11 16:35 ` Paul E. McKenney
2009-12-11 13:41 ` [patch 1/9] sys: Fix missing rcu protection for __task_cred() access David Howells
2009-12-11 13:46 ` [patch 2/9] fs: Add missing rcu protection for __task_cred() in sys_ioprio_get David Howells
2009-12-11 13:46 ` [patch 3/9] proc: Add missing rcu protection for __task_cred() in task_sig() David Howells
2009-12-11 13:49 ` [patch 4/9] oom: Add missing rcu protection of __task_cred() in dump_tasks David Howells
2009-12-11 13:52 ` Thomas Gleixner
2009-12-11 13:52 ` [patch 5/9] security: Use get_task_cred() in keyctl_session_to_parent() David Howells
2009-12-11 13:53 ` [patch 6/9] signal: Fix racy access to __task_cred in kill_pid_info_as_uid() David Howells
2009-12-11 14:00 ` [patch 8/9] Documentation: Fix invalid rcu assumptions David Howells
2009-12-11 16:07 ` Linus Torvalds
2009-12-11 16:37 ` Paul E. McKenney
2009-12-11 18:08 ` Thomas Gleixner
2009-12-11 14:01 ` [patch 9/9] security: Fix invalid rcu assumptions in comments David Howells
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