network: TC - introduce pfifo_head_drop

This adds the required changes to gain access to
the head drop classfull queuing discipline named
pfifo_head_drop.

man/systemd.network.xml

@@ -2664,6 +2664,33 @@
     </variablelist>
   </refsect1>
 
+  <refsect1>
+    <title>[PFIFOHeadDrop] Section Options</title>
+    <para>The <literal>[PFIFOHeadDrop]</literal> section manages the queueing discipline (qdisc) of
+    Packet First In First Out Head Drop (pfifo_head_drop).</para>
+
+    <variablelist class='network-directives'>
+      <varlistentry>
+        <term><varname>Parent=</varname></term>
+        <listitem>
+          <para>As in <literal>[PFIFO]</literal> section.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>Handle=</varname></term>
+        <listitem>
+          <para>As in <literal>[PFIFO]</literal> section..</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>PacketLimit=</varname></term>
+        <listitem>
+          <para>As in <literal>[PFIFO]</literal> section.</para></listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
   <refsect1>
     <title>[CAKE] Section Options</title>
     <para>The <literal>[CAKE]</literal> section manages the queueing discipline (qdisc) of

src/network/networkd-network-gperf.gperf

@@ -280,6 +280,9 @@ DeficitRoundRobinSchedulerClass.Quantum,     config_parse_drr_size,
 PFIFO.Parent,                                config_parse_qdisc_parent,                                QDISC_KIND_PFIFO,              0
 PFIFO.Handle,                                config_parse_qdisc_handle,                                QDISC_KIND_PFIFO,              0
 PFIFO.PacketLimit,                           config_parse_pfifo_size,                                  QDISC_KIND_PFIFO,              0
+PFIFOHeadDrop.Parent,                        config_parse_qdisc_parent,                                QDISC_KIND_PFIFO_HEAD_DROP,    0
+PFIFOHeadDrop.Handle,                        config_parse_qdisc_handle,                                QDISC_KIND_PFIFO_HEAD_DROP,    0
+PFIFOHeadDrop.PacketLimit,                   config_parse_pfifo_size,                                  QDISC_KIND_PFIFO_HEAD_DROP,    0
 FairQueueing.Parent,                         config_parse_qdisc_parent,                                QDISC_KIND_FQ,                 0
 FairQueueing.Handle,                         config_parse_qdisc_handle,                                QDISC_KIND_FQ,                 0
 FairQueueing.PacketLimit,                    config_parse_fair_queueing_u32,                           QDISC_KIND_FQ,                 0

src/network/networkd-network.c

@@ -492,6 +492,7 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
                               "DeficitRoundRobinScheduler\0"
                               "DeficitRoundRobinSchedulerClass\0"
                               "PFIFO\0"
+                              "PFIFOHeadDrop\0"
                               "FairQueueing\0"
                               "FairQueueingControlledDelay\0"
                               "GenericRandomEarlyDetection\0"

src/network/tc/fifo.c

@@ -26,6 +26,9 @@ static int fifo_fill_message(Link *link, QDisc *qdisc, sd_netlink_message *req)
         case QDISC_KIND_BFIFO:
                 fifo = BFIFO(qdisc);
                 break;
+        case QDISC_KIND_PFIFO_HEAD_DROP:
+                fifo = PFIFO_HEAD_DROP(qdisc);
+                break;
         default:
                 assert_not_reached("Invalid QDisc kind.");
         }
@@ -61,14 +64,23 @@ int config_parse_pfifo_size(
         assert(rvalue);
         assert(data);
 
-        r = qdisc_new_static(QDISC_KIND_PFIFO, network, filename, section_line, &qdisc);
+        r = qdisc_new_static(ltype, 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");
 
-        fifo = PFIFO(qdisc);
+        switch(qdisc->kind) {
+        case QDISC_KIND_PFIFO:
+                fifo = PFIFO(qdisc);
+                break;
+        case QDISC_KIND_PFIFO_HEAD_DROP:
+                fifo = PFIFO_HEAD_DROP(qdisc);
+                break;
+        default:
+                assert_not_reached("Invalid QDisc kind.");
+        }
 
         if (isempty(rvalue)) {
                 fifo->limit = 0;
@@ -147,7 +159,6 @@ int config_parse_bfifo_size(
         return 0;
 }
 
-
 const QDiscVTable pfifo_vtable = {
         .object_size = sizeof(FirstInFirstOut),
         .tca_kind = "pfifo",
@@ -159,3 +170,9 @@ const QDiscVTable bfifo_vtable = {
        .tca_kind = "bfifo",
        .fill_message = fifo_fill_message,
 };
+
+const QDiscVTable pfifo_head_drop_vtable = {
+       .object_size = sizeof(FirstInFirstOut),
+       .tca_kind = "pfifo_head_drop",
+       .fill_message = fifo_fill_message,
+};

src/network/tc/fifo.h

@@ -13,9 +13,11 @@ typedef struct FirstInFirstOut {
 
 DEFINE_QDISC_CAST(PFIFO, FirstInFirstOut);
 DEFINE_QDISC_CAST(BFIFO, FirstInFirstOut);
+DEFINE_QDISC_CAST(PFIFO_HEAD_DROP, FirstInFirstOut);
 
 extern const QDiscVTable pfifo_vtable;
 extern const QDiscVTable bfifo_vtable;
+extern const QDiscVTable pfifo_head_drop_vtable;
 
 CONFIG_PARSER_PROTOTYPE(config_parse_pfifo_size);
 CONFIG_PARSER_PROTOTYPE(config_parse_bfifo_size);

src/network/tc/qdisc.c

@@ -27,6 +27,7 @@ const QDiscVTable * const qdisc_vtable[_QDISC_KIND_MAX] = {
         [QDISC_KIND_NETEM] = &netem_vtable,
         [QDISC_KIND_PIE] = &pie_vtable,
         [QDISC_KIND_PFIFO] = &pfifo_vtable,
+        [QDISC_KIND_PFIFO_HEAD_DROP] = &pfifo_head_drop_vtable,
         [QDISC_KIND_SFB] = &sfb_vtable,
         [QDISC_KIND_SFQ] = &sfq_vtable,
         [QDISC_KIND_TBF] = &tbf_vtable,

src/network/tc/qdisc.h

@@ -19,6 +19,7 @@ typedef enum QDiscKind {
         QDISC_KIND_HTB,
         QDISC_KIND_NETEM,
         QDISC_KIND_PFIFO,
+        QDISC_KIND_PFIFO_HEAD_DROP,
         QDISC_KIND_PIE,
         QDISC_KIND_SFB,
         QDISC_KIND_SFQ,

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

@@ -364,6 +364,10 @@ LimitSize=
 Parent=
 Handle=
 PacketLimit=
+[PFIFOHeadDrop]
+Parent=
+Handle=
+PacketLimit=
 [GenericRandomEarlyDetection]
 Parent=
 Handle=