X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=kernel%2Fkernel%2Ffork.c;h=1b0e656f60e80d4f0af9ece3829ebf18d94587cc;hb=refs%2Fchanges%2F53%2F2653%2F1;hp=dd407cea059a6692b4e0513f3dd2c5a1f3f9b828;hpb=342fa5dfa053559f47caad657132522496dcf1b3;p=kvmfornfv.git

diff --git a/kernel/kernel/fork.c b/kernel/kernel/fork.c
index dd407cea0..1b0e656f6 100644
--- a/kernel/kernel/fork.c
+++ b/kernel/kernel/fork.c
@@ -1888,13 +1888,21 @@ static int check_unshare_flags(unsigned long unshare_flags)
 				CLONE_NEWUSER|CLONE_NEWPID))
 		return -EINVAL;
 	/*
-	 * Not implemented, but pretend it works if there is nothing to
-	 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
-	 * needs to unshare vm.
+	 * Not implemented, but pretend it works if there is nothing
+	 * to unshare.  Note that unsharing the address space or the
+	 * signal handlers also need to unshare the signal queues (aka
+	 * CLONE_THREAD).
 	 */
 	if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
-		/* FIXME: get_task_mm() increments ->mm_users */
-		if (atomic_read(&current->mm->mm_users) > 1)
+		if (!thread_group_empty(current))
+			return -EINVAL;
+	}
+	if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
+		if (atomic_read(&current->sighand->count) > 1)
+			return -EINVAL;
+	}
+	if (unshare_flags & CLONE_VM) {
+		if (!current_is_single_threaded())
 			return -EINVAL;
 	}
 
@@ -1962,16 +1970,16 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
 	 */
 	if (unshare_flags & CLONE_NEWUSER)
 		unshare_flags |= CLONE_THREAD | CLONE_FS;
-	/*
-	 * If unsharing a thread from a thread group, must also unshare vm.
-	 */
-	if (unshare_flags & CLONE_THREAD)
-		unshare_flags |= CLONE_VM;
 	/*
 	 * If unsharing vm, must also unshare signal handlers.
 	 */
 	if (unshare_flags & CLONE_VM)
 		unshare_flags |= CLONE_SIGHAND;
+	/*
+	 * If unsharing a signal handlers, must also unshare the signal queues.
+	 */
+	if (unshare_flags & CLONE_SIGHAND)
+		unshare_flags |= CLONE_THREAD;
 	/*
 	 * If unsharing namespace, must also unshare filesystem information.
 	 */