From: Oleg Nesterov <oleg@tv-sign.ru>
To: Andrew Morton <akpm@osdl.org>
Cc: ebiederm@xmission.com, torvalds@osdl.org,
linux-kernel@vger.kernel.org, janak@us.ibm.com,
viro@ftp.linux.org.uk, hch@lst.de, mtk-manpages@gmx.net,
ak@muc.de, paulus@samba.org
Subject: [PATCH] implement unshare(CLONE_SIGHAND) for single-thread case
Date: Sat, 18 Mar 2006 16:13:24 +0300 [thread overview]
Message-ID: <441C0774.C5FA688D@tv-sign.ru> (raw)
In-Reply-To: 20060317125607.78a5dbe4.akpm@osdl.org
on top of (already merged)
unshare-use-rcu_assign_pointer-when-setting-sighand.patch
depends on
convert-sighand_cache-to-use-slab_destroy_by_rcu.patch
Implement unshare(CLONE_SIGHAND) for single-thread case.
I think it is not possible to do it for multithread case without
complication of copy_process().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- MM/kernel/fork.c~ 2006-03-18 16:23:23.000000000 +0300
+++ MM/kernel/fork.c 2006-03-18 17:00:39.000000000 +0300
@@ -1483,18 +1483,24 @@ static int unshare_namespace(unsigned lo
}
/*
- * Unsharing of sighand for tasks created with CLONE_SIGHAND is not
- * supported yet
+ * Unsharing of sighand is only supported for single-thread applications
*/
static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
{
- struct sighand_struct *sigh = current->sighand;
-
if ((unshare_flags & CLONE_SIGHAND) &&
- (sigh && atomic_read(&sigh->count) > 1))
- return -EINVAL;
- else
- return 0;
+ atomic_read(¤t->sighand->count) > 1) {
+
+ if (!thread_group_empty(current))
+ return -EINVAL;
+
+ *new_sighp = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
+ if (unlikely(*new_sighp == NULL))
+ return -ENOMEM;
+
+ atomic_set(&(*new_sighp)->count, 1);
+ }
+
+ return 0;
}
/*
@@ -1579,7 +1585,18 @@ asmlinkage long sys_unshare(unsigned lon
if ((err = unshare_semundo(unshare_flags, &new_ulist)))
goto bad_unshare_cleanup_fd;
- if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist) {
+ if (new_sigh) {
+ sigh = current->sighand;
+ write_lock_irq(&tasklist_lock);
+ spin_lock(&sigh->siglock);
+ memcpy(new_sigh->action, sigh->action, sizeof(sigh->action));
+ rcu_assign_pointer(current->sighand, new_sigh);
+ spin_unlock(&sigh->siglock);
+ write_unlock_irq(&tasklist_lock);
+ new_sigh = sigh;
+ }
+
+ if (new_fs || new_ns || new_mm || new_fd || new_ulist) {
task_lock(current);
@@ -1595,12 +1612,6 @@ asmlinkage long sys_unshare(unsigned lon
new_ns = ns;
}
- if (new_sigh) {
- sigh = current->sighand;
- rcu_assign_pointer(current->sighand, new_sigh);
- new_sigh = sigh;
- }
-
if (new_mm) {
mm = current->mm;
active_mm = current->active_mm;
next prev parent reply other threads:[~2006-03-18 13:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-16 16:49 [PATCH] unshare: Cleanup up the sys_unshare interface before we are committed Eric W. Biederman
2006-03-16 17:31 ` [PATCH] unshare: Use rcu_assign_pointer when setting sighand Eric W. Biederman
2006-03-17 6:48 ` Paul E. McKenney
2006-03-17 17:44 ` Oleg Nesterov
2006-03-17 20:56 ` Andrew Morton
2006-03-18 13:12 ` Oleg Nesterov
2006-03-18 15:43 ` Janak Desai
2006-03-18 17:24 ` Oleg Nesterov
2006-03-18 17:41 ` [PATCH] for 2.6.16, disable unshare_vm() Oleg Nesterov
2006-03-18 18:10 ` Linus Torvalds
2006-03-18 18:29 ` Ulrich Drepper
2006-03-18 18:48 ` Janak Desai
2016-03-14 13:15 ` unshare(CLONE_VM) Re: [PATCH] unshare: Use rcu_assign_pointer when setting sighand Julian Smith
2016-03-14 18:35 ` Linus Torvalds
2006-03-18 13:13 ` Oleg Nesterov [this message]
2006-03-18 15:10 ` [PATCH] unshare: Error if passed unsupported flags Eric W. Biederman
2006-03-18 15:33 ` Janak Desai
2006-03-18 16:29 ` [PATCH] unshare: Use rcu_assign_pointer when setting sighand Janak Desai
2006-03-16 19:40 ` [PATCH] unshare: Cleanup up the sys_unshare interface before we are committed Michael Kerrisk
2006-03-16 20:33 ` Andrew Morton
2006-03-16 20:41 ` Linus Torvalds
2006-03-16 21:58 ` Eric W. Biederman
2006-03-16 22:19 ` Andrew Morton
2006-03-16 21:36 ` Janak Desai
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