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author | Rusty Russell <rusty@rustcorp.com.au> | 2008-12-30 08:02:35 +1030 |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-12-30 08:02:35 +1030 |
commit | 33edcf133ba93ecba2e4b6472e97b689895d805c (patch) | |
tree | 327d7a20acef64005e7c5ccbfa1265be28aeb6ac /lib/is_single_threaded.c | |
parent | be4d638c1597580ed2294d899d9f1a2cd10e462c (diff) | |
parent | 3c92ec8ae91ecf59d88c798301833d7cf83f2179 (diff) | |
download | op-kernel-dev-33edcf133ba93ecba2e4b6472e97b689895d805c.zip op-kernel-dev-33edcf133ba93ecba2e4b6472e97b689895d805c.tar.gz |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Diffstat (limited to 'lib/is_single_threaded.c')
-rw-r--r-- | lib/is_single_threaded.c | 45 |
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 0000000..f1ed2fe --- /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; +} |