network: tc- introduce PIE

Proportional Integral controller-Enhanced (PIE) is a control
theoretic active queue management scheme. It is based on the
proportional integral controller but aims to control delay.

http://man7.org/linux/man-pages/man8/tc-pie.8.html

man/systemd.network.xml

@@ -2500,6 +2500,38 @@
     </variablelist>
   </refsect1>
 
+  <refsect1>
+    <title>[PIE] Section Options</title>
+    <para>The <literal>[PIE]</literal> section manages the queueing discipline
+    (qdisc) of Proportional Integral controller-Enhanced (PIE).</para>
+
+    <variablelist class='network-directives'>
+      <varlistentry>
+        <term><varname>Parent=</varname></term>
+        <listitem>
+          <para>Specifies the parent Queueing Discipline (qdisc). Takes one of <literal>root</literal>,
+          <literal>clsact</literal> or <literal>ingress</literal>. Defaults to <literal>root</literal>.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>Handle=</varname></term>
+        <listitem>
+          <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
+          Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>PacketLimit=</varname></term>
+        <listitem>
+          <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached, incoming packets are
+          dropped. An unsigned integer ranges 1 to 4294967294. Defaults to unset and kernel's default is used.</para>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
   <refsect1>
     <title>[StochasticFairBlue] Section Options</title>
     <para>The <literal>[StochasticFairBlue]</literal> section manages the queueing discipline

src/network/meson.build

@@ -123,6 +123,8 @@ sources = files('''
         tc/htb.h
         tc/netem.c
         tc/netem.h
+        tc/pie.c
+        tc/pie.h
         tc/qdisc.c
         tc/qdisc.h
         tc/sfb.c

src/network/networkd-network-gperf.gperf

@@ -313,6 +313,9 @@ NetworkEmulator.DelayJitterSec,              config_parse_network_emulator_delay
 NetworkEmulator.LossRate,                    config_parse_network_emulator_rate,                       QDISC_KIND_NETEM,              0
 NetworkEmulator.DuplicateRate,               config_parse_network_emulator_rate,                       QDISC_KIND_NETEM,              0
 NetworkEmulator.PacketLimit,                 config_parse_network_emulator_packet_limit,               QDISC_KIND_NETEM,              0
+PIE.Parent,                                  config_parse_qdisc_parent,                                QDISC_KIND_PIE,                0
+PIE.Handle,                                  config_parse_qdisc_handle,                                QDISC_KIND_PIE,                0
+PIE.PacketLimit,                             config_parse_pie_packet_limit,                            QDISC_KIND_PIE,                0
 StochasticFairBlue.Parent,                   config_parse_qdisc_parent,                                QDISC_KIND_SFB,                0
 StochasticFairBlue.Handle,                   config_parse_qdisc_handle,                                QDISC_KIND_SFB,                0
 StochasticFairBlue.PacketLimit,              config_parse_stochastic_fair_blue_u32,                    QDISC_KIND_SFB,                0

src/network/networkd-network.c

@@ -495,6 +495,7 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
                               "HierarchyTokenBucket\0"
                               "HierarchyTokenBucketClass\0"
                               "NetworkEmulator\0"
+                              "PIE\0"
                               "StochasticFairBlue\0"
                               "StochasticFairnessQueueing\0"
                               "TokenBucketFilter\0"

src/network/tc/pie.c

@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2020 VMware, Inc. */
+
+#include <linux/pkt_sched.h>
+
+#include "alloc-util.h"
+#include "conf-parser.h"
+#include "pie.h"
+#include "netlink-util.h"
+#include "parse-util.h"
+#include "string-util.h"
+
+static int pie_fill_message(Link *link, QDisc *qdisc, sd_netlink_message *req) {
+        proportional_integral_controller_enhanced *pie;
+        int r;
+
+        assert(link);
+        assert(qdisc);
+        assert(req);
+
+        pie = PIE(qdisc);
+
+        r = sd_netlink_message_open_container_union(req, TCA_OPTIONS, "pie");
+        if (r < 0)
+                return log_link_error_errno(link, r, "Could not open container TCA_OPTIONS: %m");
+
+        if (pie->packet_limit > 0) {
+                r = sd_netlink_message_append_u32(req, TCA_PIE_LIMIT, pie->packet_limit);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not append TCA_PIE_PLIMIT attribute: %m");
+        }
+
+        r = sd_netlink_message_close_container(req);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Could not close container TCA_OPTIONS: %m");
+
+        return 0;
+}
+
+int config_parse_pie_packet_limit(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        _cleanup_(qdisc_free_or_set_invalidp) QDisc *qdisc = NULL;
+        proportional_integral_controller_enhanced *pie;
+        Network *network = data;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = qdisc_new_static(QDISC_KIND_PIE, network, filename, section_line, &qdisc);
+        if (r == -ENOMEM)
+                return log_oom();
+        if (r < 0)
+                return log_syntax(unit, LOG_ERR, filename, line, r,
+                                  "More than one kind of queueing discipline, ignoring assignment: %m");
+
+        pie = PIE(qdisc);
+
+        if (isempty(rvalue)) {
+                pie->packet_limit = 0;
+
+                qdisc = NULL;
+                return 0;
+        }
+
+        r = safe_atou32(rvalue, &pie->packet_limit);
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r,
+                           "Failed to parse '%s=', ignoring assignment: %s",
+                           lvalue, rvalue);
+                return 0;
+        }
+
+        qdisc = NULL;
+
+        return 0;
+}
+
+const QDiscVTable pie_vtable = {
+        .object_size = sizeof(proportional_integral_controller_enhanced),
+        .tca_kind = "pie",
+        .fill_message = pie_fill_message,
+};

src/network/tc/pie.h

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ * Copyright © 2020 VMware, Inc. */
+#pragma once
+
+#include "conf-parser.h"
+#include "qdisc.h"
+
+typedef struct proportional_integral_controller_enhanced {
+        QDisc meta;
+
+        uint32_t packet_limit;
+} proportional_integral_controller_enhanced;
+
+DEFINE_QDISC_CAST(PIE, proportional_integral_controller_enhanced);
+extern const QDiscVTable pie_vtable;
+
+CONFIG_PARSER_PROTOTYPE(config_parse_pie_packet_limit);

src/network/tc/qdisc.c

@@ -23,6 +23,7 @@ const QDiscVTable * const qdisc_vtable[_QDISC_KIND_MAX] = {
         [QDISC_KIND_GRED] = &gred_vtable,
         [QDISC_KIND_HTB] = &htb_vtable,
         [QDISC_KIND_NETEM] = &netem_vtable,
+        [QDISC_KIND_PIE] = &pie_vtable,
         [QDISC_KIND_PFIFO] = &pfifo_vtable,
         [QDISC_KIND_SFB] = &sfb_vtable,
         [QDISC_KIND_SFQ] = &sfq_vtable,

src/network/tc/qdisc.h

@@ -17,6 +17,7 @@ typedef enum QDiscKind {
         QDISC_KIND_HTB,
         QDISC_KIND_NETEM,
         QDISC_KIND_PFIFO,
+        QDISC_KIND_PIE,
         QDISC_KIND_SFB,
         QDISC_KIND_SFQ,
         QDISC_KIND_TBF,
@@ -85,6 +86,7 @@ CONFIG_PARSER_PROTOTYPE(config_parse_qdisc_handle);
 #include "fq.h"
 #include "gred.h"
 #include "htb.h"
+#include "pie.h"
 #include "netem.h"
 #include "sfb.h"
 #include "sfq.h"

test/fuzz/fuzz-network-parser/directives.network

@@ -370,3 +370,7 @@ GenericRIO=
 Parent=
 Handle=
 PacketLimit=
+[PIE]
+Parent=
+Handle=
+PacketLimit=