selinux: annotate false positive data race to avoid KCSAN warnings

KCSAN flags the check of isec->initialized by
__inode_security_revalidate() as a data race. This is indeed a racy
check, but inode_doinit_with_dentry() will recheck with isec->lock held.
Annotate the check with the data_race() macro to silence the KCSAN false
positive.

Reported-by: syzbot+319ed1769c0078257262@syzkaller.appspotmail.com
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -282,8 +282,13 @@ static int __inode_security_revalidate(struct inode *inode,
 
 	might_sleep_if(may_sleep);
 
+	/*
+	 * The check of isec->initialized below is racy but
+	 * inode_doinit_with_dentry() will recheck with
+	 * isec->lock held.
+	 */
 	if (selinux_initialized() &&
-	    isec->initialized != LABEL_INITIALIZED) {
+	    data_race(isec->initialized != LABEL_INITIALIZED)) {
 		if (!may_sleep)
 			return -ECHILD;