seccomp: Replace BUG(!spin_is_locked()) with assert_spin_lock

Current upstream kernel hangs with mips and powerpc targets in
uniprocessor mode if SECCOMP is configured.

Bisect points to commit dbd952127d11 ("seccomp: introduce writer locking").
Turns out that code such as
	BUG_ON(!spin_is_locked(&list_lock));
can not be used in uniprocessor mode because spin_is_locked() always
returns false in this configuration, and that assert_spin_locked()
exists for that very purpose and must be used instead.

Fixes: dbd952127d11 ("seccomp: introduce writer locking")
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 1380d8ace334..0cf9cdb6e491 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1105,7 +1105,7 @@ static void copy_seccomp(struct task_struct *p)
          * needed because this new task is not yet running and cannot
          * be racing exec.
          */
-        BUG_ON(!spin_is_locked(&current->sighand->siglock));
+        assert_spin_locked(&current->sighand->siglock);
 
         /* Ref-count the new filter user, and assign it. */
         get_seccomp_filter(current);