1 files changed, 183 insertions, 0 deletions

diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
new file mode 100644
index 000000000000..76f034087743
--- /dev/null
+++ b/include/net/busy_poll.h
@@ -0,0 +1,183 @@
+/*
+ * Low Latency Sockets
+ * Copyright(c) 2013 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Author: Eliezer Tamir
+ *
+ * Contact Information:
+ * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
+ */
+
+#ifndef _LINUX_NET_LL_POLL_H
+#define _LINUX_NET_LL_POLL_H
+
+#include <linux/netdevice.h>
+#include <net/ip.h>
+
+#ifdef CONFIG_NET_LL_RX_POLL
+
+struct napi_struct;
+extern unsigned int sysctl_net_ll_read __read_mostly;
+extern unsigned int sysctl_net_ll_poll __read_mostly;
+
+/* return values from ndo_ll_poll */
+#define LL_FLUSH_FAILED         -1
+#define LL_FLUSH_BUSY           -2
+
+static inline bool net_busy_loop_on(void)
+{
+        return sysctl_net_ll_poll;
+}
+
+/* a wrapper to make debug_smp_processor_id() happy
+ * we can use sched_clock() because we don't care much about precision
+ * we only care that the average is bounded
+ */
+#ifdef CONFIG_DEBUG_PREEMPT
+static inline u64 busy_loop_us_clock(void)
+{
+        u64 rc;
+
+        preempt_disable_notrace();
+        rc = sched_clock();
+        preempt_enable_no_resched_notrace();
+
+        return rc >> 10;
+}
+#else /* CONFIG_DEBUG_PREEMPT */
+static inline u64 busy_loop_us_clock(void)
+{
+        return sched_clock() >> 10;
+}
+#endif /* CONFIG_DEBUG_PREEMPT */
+
+static inline unsigned long sk_busy_loop_end_time(struct sock *sk)
+{
+        return busy_loop_us_clock() + ACCESS_ONCE(sk->sk_ll_usec);
+}
+
+/* in poll/select we use the global sysctl_net_ll_poll value */
+static inline unsigned long busy_loop_end_time(void)
+{
+        return busy_loop_us_clock() + ACCESS_ONCE(sysctl_net_ll_poll);
+}
+
+static inline bool sk_can_busy_loop(struct sock *sk)
+{
+        return sk->sk_ll_usec && sk->sk_napi_id &&
+               !need_resched() && !signal_pending(current);
+}
+
+
+static inline bool busy_loop_timeout(unsigned long end_time)
+{
+        unsigned long now = busy_loop_us_clock();
+
+        return time_after(now, end_time);
+}
+
+/* when used in sock_poll() nonblock is known at compile time to be true
+ * so the loop and end_time will be optimized out
+ */
+static inline bool sk_busy_loop(struct sock *sk, int nonblock)
+{
+        unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0;
+        const struct net_device_ops *ops;
+        struct napi_struct *napi;
+        int rc = false;
+
+        /*
+         * rcu read lock for napi hash
+         * bh so we don't race with net_rx_action
+         */
+        rcu_read_lock_bh();
+
+        napi = napi_by_id(sk->sk_napi_id);
+        if (!napi)
+                goto out;
+
+        ops = napi->dev->netdev_ops;
+        if (!ops->ndo_ll_poll)
+                goto out;
+
+        do {
+                rc = ops->ndo_ll_poll(napi);
+
+                if (rc == LL_FLUSH_FAILED)
+                        break; /* permanent failure */
+
+                if (rc > 0)
+                        /* local bh are disabled so it is ok to use _BH */
+                        NET_ADD_STATS_BH(sock_net(sk),
+                                         LINUX_MIB_LOWLATENCYRXPACKETS, rc);
+
+        } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
+                 !need_resched() && !busy_loop_timeout(end_time));
+
+        rc = !skb_queue_empty(&sk->sk_receive_queue);
+out:
+        rcu_read_unlock_bh();
+        return rc;
+}
+
+/* used in the NIC receive handler to mark the skb */
+static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi)
+{
+        skb->napi_id = napi->napi_id;
+}
+
+/* used in the protocol hanlder to propagate the napi_id to the socket */
+static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
+{
+        sk->sk_napi_id = skb->napi_id;
+}
+
+#else /* CONFIG_NET_LL_RX_POLL */
+static inline unsigned long net_busy_loop_on(void)
+{
+        return 0;
+}
+
+static inline unsigned long busy_loop_end_time(void)
+{
+        return 0;
+}
+
+static inline bool sk_can_busy_loop(struct sock *sk)
+{
+        return false;
+}
+
+static inline bool sk_busy_poll(struct sock *sk, int nonblock)
+{
+        return false;
+}
+
+static inline void skb_mark_ll(struct sk_buff *skb, struct napi_struct *napi)
+{
+}
+
+static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
+{
+}
+
+static inline bool busy_loop_timeout(unsigned long end_time)
+{
+        return true;
+}
+
+#endif /* CONFIG_NET_LL_RX_POLL */
+#endif /* _LINUX_NET_LL_POLL_H */