Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 179 insertions, 0 deletions

diff --git a/samples/bpf/hbm_out_kern.c b/samples/bpf/hbm_out_kern.c
new file mode 100644
index 0000000000..829934bd43
--- /dev/null
+++ b/samples/bpf/hbm_out_kern.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * Sample Host Bandwidth Manager (HBM) BPF program.
+ *
+ * A cgroup skb BPF egress program to limit cgroup output bandwidth.
+ * It uses a modified virtual token bucket queue to limit average
+ * egress bandwidth. The implementation uses credits instead of tokens.
+ * Negative credits imply that queueing would have happened (this is
+ * a virtual queue, so no queueing is done by it. However, queueing may
+ * occur at the actual qdisc (which is not used for rate limiting).
+ *
+ * This implementation uses 3 thresholds, one to start marking packets and
+ * the other two to drop packets:
+ *                                  CREDIT
+ *        - <--------------------------|------------------------> +
+ *              |    |          |      0
+ *              |  Large pkt    |
+ *              |  drop thresh  |
+ *   Small pkt drop             Mark threshold
+ *       thresh
+ *
+ * The effect of marking depends on the type of packet:
+ * a) If the packet is ECN enabled and it is a TCP packet, then the packet
+ *    is ECN marked.
+ * b) If the packet is a TCP packet, then we probabilistically call tcp_cwr
+ *    to reduce the congestion window. The current implementation uses a linear
+ *    distribution (0% probability at marking threshold, 100% probability
+ *    at drop threshold).
+ * c) If the packet is not a TCP packet, then it is dropped.
+ *
+ * If the credit is below the drop threshold, the packet is dropped. If it
+ * is a TCP packet, then it also calls tcp_cwr since packets dropped by
+ * by a cgroup skb BPF program do not automatically trigger a call to
+ * tcp_cwr in the current kernel code.
+ *
+ * This BPF program actually uses 2 drop thresholds, one threshold
+ * for larger packets (>= 120 bytes) and another for smaller packets. This
+ * protects smaller packets such as SYNs, ACKs, etc.
+ *
+ * The default bandwidth limit is set at 1Gbps but this can be changed by
+ * a user program through a shared BPF map. In addition, by default this BPF
+ * program does not limit connections using loopback. This behavior can be
+ * overwritten by the user program. There is also an option to calculate
+ * some statistics, such as percent of packets marked or dropped, which
+ * the user program can access.
+ *
+ * A latter patch provides such a program (hbm.c)
+ */
+
+#include "hbm_kern.h"
+
+SEC("cgroup_skb/egress")
+int _hbm_out_cg(struct __sk_buff *skb)
+{
+	struct hbm_pkt_info pkti;
+	int len = skb->len;
+	unsigned int queue_index = 0;
+	unsigned long long curtime;
+	int credit;
+	signed long long delta = 0, new_credit;
+	int max_credit = MAX_CREDIT;
+	bool congestion_flag = false;
+	bool drop_flag = false;
+	bool cwr_flag = false;
+	bool ecn_ce_flag = false;
+	struct hbm_vqueue *qdp;
+	struct hbm_queue_stats *qsp = NULL;
+	int rv = ALLOW_PKT;
+
+	qsp = bpf_map_lookup_elem(&queue_stats, &queue_index);
+	if (qsp != NULL && !qsp->loopback && (skb->ifindex == 1))
+		return ALLOW_PKT;
+
+	hbm_get_pkt_info(skb, &pkti);
+
+	// We may want to account for the length of headers in len
+	// calculation, like ETH header + overhead, specially if it
+	// is a gso packet. But I am not doing it right now.
+
+	qdp = bpf_get_local_storage(&queue_state, 0);
+	if (!qdp)
+		return ALLOW_PKT;
+	else if (qdp->lasttime == 0)
+		hbm_init_vqueue(qdp, 1024);
+
+	curtime = bpf_ktime_get_ns();
+
+	// Begin critical section
+	bpf_spin_lock(&qdp->lock);
+	credit = qdp->credit;
+	delta = curtime - qdp->lasttime;
+	/* delta < 0 implies that another process with a curtime greater
+	 * than ours beat us to the critical section and already added
+	 * the new credit, so we should not add it ourselves
+	 */
+	if (delta > 0) {
+		qdp->lasttime = curtime;
+		new_credit = credit + CREDIT_PER_NS(delta, qdp->rate);
+		if (new_credit > MAX_CREDIT)
+			credit = MAX_CREDIT;
+		else
+			credit = new_credit;
+	}
+	credit -= len;
+	qdp->credit = credit;
+	bpf_spin_unlock(&qdp->lock);
+	// End critical section
+
+	// Check if we should update rate
+	if (qsp != NULL && (qsp->rate * 128) != qdp->rate) {
+		qdp->rate = qsp->rate * 128;
+		bpf_printk("Updating rate: %d (1sec:%llu bits)\n",
+			   (int)qdp->rate,
+			   CREDIT_PER_NS(1000000000, qdp->rate) * 8);
+	}
+
+	// Set flags (drop, congestion, cwr)
+	// Dropping => we are congested, so ignore congestion flag
+	if (credit < -DROP_THRESH ||
+	    (len > LARGE_PKT_THRESH && credit < -LARGE_PKT_DROP_THRESH)) {
+		// Very congested, set drop packet
+		drop_flag = true;
+		if (pkti.ecn)
+			congestion_flag = true;
+		else if (pkti.is_tcp)
+			cwr_flag = true;
+	} else if (credit < 0) {
+		// Congested, set congestion flag
+		if (pkti.ecn || pkti.is_tcp) {
+			if (credit < -MARK_THRESH)
+				congestion_flag = true;
+			else
+				congestion_flag = false;
+		} else {
+			congestion_flag = true;
+		}
+	}
+
+	if (congestion_flag) {
+		if (bpf_skb_ecn_set_ce(skb)) {
+			ecn_ce_flag = true;
+		} else {
+			if (pkti.is_tcp) {
+				unsigned int rand = bpf_get_prandom_u32();
+
+				if (-credit >= MARK_THRESH +
+				    (rand % MARK_REGION_SIZE)) {
+					// Do congestion control
+					cwr_flag = true;
+				}
+			} else if (len > LARGE_PKT_THRESH) {
+				// Problem if too many small packets?
+				drop_flag = true;
+			}
+		}
+	}
+
+	if (qsp != NULL)
+		if (qsp->no_cn)
+			cwr_flag = false;
+
+	hbm_update_stats(qsp, len, curtime, congestion_flag, drop_flag,
+			 cwr_flag, ecn_ce_flag, &pkti, credit);
+
+	if (drop_flag) {
+		__sync_add_and_fetch(&(qdp->credit), len);
+		rv = DROP_PKT;
+	}
+
+	if (cwr_flag)
+		rv |= 2;
+	return rv;
+}
+char _license[] SEC("license") = "GPL";