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authorDavid Howells <dhowells@redhat.com>2008-11-14 10:39:21 +1100
committerJames Morris <jmorris@namei.org>2008-11-14 10:39:21 +1100
commit6cc88bc45ce8043171089c9592da223dfab91823 (patch)
treef89bf8162895a5eb89ea7969098876e08a8999d8 /lib/is_single_threaded.c
parentbb952bb98a7e479262c7eb25d5592545a3af147d (diff)
downloadlinux-stericsson-6cc88bc45ce8043171089c9592da223dfab91823.tar.gz
CRED: Rename is_single_threaded() to is_wq_single_threaded()
Rename is_single_threaded() to is_wq_single_threaded() so that a new is_single_threaded() can be created that refers to tasks rather than waitqueues. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'lib/is_single_threaded.c')
-rw-r--r--lib/is_single_threaded.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/lib/is_single_threaded.c b/lib/is_single_threaded.c
new file mode 100644
index 000000000000..f1ed2fe76c65
--- /dev/null
+++ b/lib/is_single_threaded.c
@@ -0,0 +1,45 @@
+/* Function to determine if a thread group is single threaded or not
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ * - Derived from security/selinux/hooks.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/sched.h>
+
+/**
+ * is_single_threaded - Determine if a thread group is single-threaded or not
+ * @p: A task in the thread group in question
+ *
+ * This returns true if the thread group to which a task belongs is single
+ * threaded, false if it is not.
+ */
+bool is_single_threaded(struct task_struct *p)
+{
+ struct task_struct *g, *t;
+ struct mm_struct *mm = p->mm;
+
+ if (atomic_read(&p->signal->count) != 1)
+ goto no;
+
+ if (atomic_read(&p->mm->mm_users) != 1) {
+ read_lock(&tasklist_lock);
+ do_each_thread(g, t) {
+ if (t->mm == mm && t != p)
+ goto no_unlock;
+ } while_each_thread(g, t);
+ read_unlock(&tasklist_lock);
+ }
+
+ return true;
+
+no_unlock:
+ read_unlock(&tasklist_lock);
+no:
+ return false;
+}