1 files changed, 122 insertions, 0 deletions
diff --git a/sys/dev/filemon/filemon_lock.c b/sys/dev/filemon/filemon_lock.c
new file mode 100644
index 0000000..6e836d1
--- /dev/null
+++ b/sys/dev/filemon/filemon_lock.c
@@ -0,0 +1,122 @@
+/*-
+ * Copyright (c) 2009-2011, Juniper Networks, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JUNIPER NETWORKS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL JUNIPER NETWORKS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+static void
+filemon_filemon_lock(struct filemon *filemon)
+{
+	mtx_lock(&filemon->mtx);
+
+	while (filemon->locker != NULL && filemon->locker != curthread)
+		cv_wait(&filemon->cv, &filemon->mtx);
+
+	filemon->locker = curthread;
+
+	mtx_unlock(&filemon->mtx);
+}
+
+static void
+filemon_filemon_unlock(struct filemon *filemon)
+{
+	mtx_lock(&filemon->mtx);
+
+	if (filemon->locker == curthread)
+		filemon->locker = NULL;
+
+	/* Wake up threads waiting. */
+	cv_broadcast(&filemon->cv);
+
+	mtx_unlock(&filemon->mtx);
+}
+
+static void
+filemon_lock_read(void)
+{
+	mtx_lock(&access_mtx);
+
+	while (access_owner != NULL || access_requester != NULL)
+		cv_wait(&access_cv, &access_mtx);
+
+	n_readers++;
+
+	/* Wake up threads waiting. */
+	cv_broadcast(&access_cv);
+
+	mtx_unlock(&access_mtx);
+}
+
+static void
+filemon_unlock_read(void)
+{
+	mtx_lock(&access_mtx);
+
+	if (n_readers > 0)
+		n_readers--;
+
+	/* Wake up a thread waiting. */
+	cv_broadcast(&access_cv);
+
+	mtx_unlock(&access_mtx);
+}
+
+static void
+filemon_lock_write(void)
+{
+	mtx_lock(&access_mtx);
+
+	while (access_owner != curthread) {
+		if (access_owner == NULL &&
+		    (access_requester == NULL ||
+		    access_requester == curthread)) {
+			access_owner = curthread;
+			access_requester = NULL;
+		} else {
+			if (access_requester == NULL)
+				access_requester = curthread;
+
+			cv_wait(&access_cv, &access_mtx);
+		}
+	}
+
+	mtx_unlock(&access_mtx);
+}
+
+static void
+filemon_unlock_write(void)
+{
+	mtx_lock(&access_mtx);
+
+	/* Sanity check that the current thread actually has the write lock. */
+	if (access_owner == curthread)
+		access_owner = NULL;
+
+	/* Wake up a thread waiting. */
+	cv_broadcast(&access_cv);
+
+	mtx_unlock(&access_mtx);
+}