+/*
+ * Distributed under the terms of the GNU GPL version 2.
+ * Copyright (c) 2010 Nicira Networks.
+ *
+ * Significant portions of this file may be copied from parts of the Linux
+ * kernel, by Linus Torvalds and others.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/hardirq.h>
+#include <linux/kernel.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+
+#include "loop_counter.h"
+
+void loop_suppress(struct datapath *dp, struct sw_flow_actions *actions)
+{
+ if (net_ratelimit())
+ pr_warn("%s: flow looped %d times, dropping\n",
+ dp_name(dp), MAX_LOOPS);
+ actions->n_actions = 0;
+}
+
+#ifndef CONFIG_PREEMPT_RT
+
+/* We use a separate counter for each CPU for both interrupt and non-interrupt
+ * context in order to keep the limit deterministic for a given packet.
+ */
+struct percpu_loop_counters {
+ struct loop_counter counters[2];
+};
+
+static DEFINE_PER_CPU(struct percpu_loop_counters, loop_counters);
+
+struct loop_counter *loop_get_counter(void)
+{
+ return &get_cpu_var(loop_counters).counters[!!in_interrupt()];
+}
+
+void loop_put_counter(void)
+{
+ put_cpu_var(loop_counters);
+}
+
+#else /* !CONFIG_PREEMPT_RT */
+
+struct loop_counter *loop_get_counter(void)
+{
+ WARN_ON(in_interrupt());
+
+ /* Only two bits of the extra_flags field in struct task_struct are
+ * used and it's an unsigned int. We hijack the most significant bits
+ * to be our counter structure. On RT kernels softirqs always run in
+ * process context so we are guaranteed to have a valid task_struct.
+ */
+
+#ifdef __LITTLE_ENDIAN
+ return (void *)(¤t->extra_flags + 1) -
+ sizeof(struct loop_counter);
+#elif __BIG_ENDIAN
+ return (struct loop_counter *)¤t->extra_flags;
+#else
+#error "Please fix <asm/byteorder.h>."
+#endif
+}
+
+void loop_put_counter(void) { }
+
+#endif /* CONFIG_PREEMPT_RT */