8 files changed, 112 insertions, 8 deletions

diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt
index d569f2a424d5..9a0319a82470 100644
--- a/Documentation/sysctl/net.txt
+++ b/Documentation/sysctl/net.txt
@@ -50,6 +50,19 @@ The maximum number of packets that kernel can handle on a NAPI interrupt,
 it's a Per-CPU variable.
 Default: 64
 
+default_qdisc
+--------------
+
+The default queuing discipline to use for network devices. This allows
+overriding the default queue discipline of pfifo_fast with an
+alternative. Since the default queuing discipline is created with the
+no additional parameters so is best suited to queuing disciplines that
+work well without configuration like stochastic fair queue (sfq),
+CoDel (codel) or fair queue CoDel (fq_codel). Don't use queuing disciplines
+like Hierarchical Token Bucket or Deficit Round Robin which require setting
+up classes and bandwidths.
+Default: pfifo_fast
+
 busy_read
 ----------------
 Low latency busy poll timeout for socket reads. (needs CONFIG_NET_RX_BUSY_POLL)
diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h
index f7c24f8fbdc5..59ec3cd15d68 100644
--- a/include/net/pkt_sched.h
+++ b/include/net/pkt_sched.h
@@ -85,6 +85,9 @@ struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops,
 
 int register_qdisc(struct Qdisc_ops *qops);
 int unregister_qdisc(struct Qdisc_ops *qops);
+void qdisc_get_default(char *id, size_t len);
+int qdisc_set_default(const char *id);
+
 void qdisc_list_del(struct Qdisc *q);
 struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle);
 struct Qdisc *qdisc_lookup_class(struct net_device *dev, u32 handle);
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 76368c9d4503..2e31bf14df00 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -316,6 +316,7 @@ extern struct Qdisc noop_qdisc;
 extern struct Qdisc_ops noop_qdisc_ops;
 extern struct Qdisc_ops pfifo_fast_ops;
 extern struct Qdisc_ops mq_qdisc_ops;
+extern const struct Qdisc_ops *default_qdisc_ops;
 
 struct Qdisc_class_common {
         u32                     classid;
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 31107abd2783..cca444190907 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -20,6 +20,7 @@
 #include <net/sock.h>
 #include <net/net_ratelimit.h>
 #include <net/busy_poll.h>
+#include <net/pkt_sched.h>
 
 static int zero = 0;
 static int one = 1;
@@ -193,6 +194,26 @@ static int flow_limit_table_len_sysctl(struct ctl_table *table, int write,
 }
 #endif /* CONFIG_NET_FLOW_LIMIT */
 
+#ifdef CONFIG_NET_SCHED
+static int set_default_qdisc(struct ctl_table *table, int write,
+                             void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+        char id[IFNAMSIZ];
+        struct ctl_table tbl = {
+                .data = id,
+                .maxlen = IFNAMSIZ,
+        };
+        int ret;
+
+        qdisc_get_default(id, IFNAMSIZ);
+
+        ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
+        if (write && ret == 0)
+                ret = qdisc_set_default(id);
+        return ret;
+}
+#endif
+
 static struct ctl_table net_core_table[] = {
 #ifdef CONFIG_NET
         {
@@ -315,7 +336,14 @@ static struct ctl_table net_core_table[] = {
                 .mode           = 0644,
                 .proc_handler   = proc_dointvec
         },
-#
+#endif
+#ifdef CONFIG_NET_SCHED
+        {
+                .procname       = "default_qdisc",
+                .mode           = 0644,
+                .maxlen         = IFNAMSIZ,
+                .proc_handler   = set_default_qdisc
+        },
 #endif
 #endif /* CONFIG_NET */
         {
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 51b968d3febb..812e57900591 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -131,6 +131,11 @@ static DEFINE_RWLOCK(qdisc_mod_lock);
  ************************************************/
 
 
+/* Qdisc to use by default */
+
+const struct Qdisc_ops *default_qdisc_ops = &pfifo_fast_ops;
+EXPORT_SYMBOL(default_qdisc_ops);
+
 /* The list of all installed queueing disciplines. */
 
 static struct Qdisc_ops *qdisc_base;
@@ -200,6 +205,58 @@ int unregister_qdisc(struct Qdisc_ops *qops)
 }
 EXPORT_SYMBOL(unregister_qdisc);
 
+/* Get default qdisc if not otherwise specified */
+void qdisc_get_default(char *name, size_t len)
+{
+        read_lock(&qdisc_mod_lock);
+        strlcpy(name, default_qdisc_ops->id, len);
+        read_unlock(&qdisc_mod_lock);
+}
+
+static struct Qdisc_ops *qdisc_lookup_default(const char *name)
+{
+        struct Qdisc_ops *q = NULL;
+
+        for (q = qdisc_base; q; q = q->next) {
+                if (!strcmp(name, q->id)) {
+                        if (!try_module_get(q->owner))
+                                q = NULL;
+                        break;
+                }
+        }
+
+        return q;
+}
+
+/* Set new default qdisc to use */
+int qdisc_set_default(const char *name)
+{
+        const struct Qdisc_ops *ops;
+
+        if (!capable(CAP_NET_ADMIN))
+                return -EPERM;
+
+        write_lock(&qdisc_mod_lock);
+        ops = qdisc_lookup_default(name);
+        if (!ops) {
+                /* Not found, drop lock and try to load module */
+                write_unlock(&qdisc_mod_lock);
+                request_module("sch_%s", name);
+                write_lock(&qdisc_mod_lock);
+
+                ops = qdisc_lookup_default(name);
+        }
+
+        if (ops) {
+                /* Set new default */
+                module_put(default_qdisc_ops->owner);
+                default_qdisc_ops = ops;
+        }
+        write_unlock(&qdisc_mod_lock);
+
+        return ops ? 0 : -ENOENT;
+}
+
 /* We know handle. Find qdisc among all qdisc's attached to device
    (root qdisc, all its children, children of children etc.)
  */
@@ -1854,6 +1911,7 @@ static int __init pktsched_init(void)
                 return err;
         }
 
+        register_qdisc(&pfifo_fast_ops);
         register_qdisc(&pfifo_qdisc_ops);
         register_qdisc(&bfifo_qdisc_ops);
         register_qdisc(&pfifo_head_drop_qdisc_ops);
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 48be3d5c0d92..5078e0c5db8d 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -530,7 +530,6 @@ struct Qdisc_ops pfifo_fast_ops __read_mostly = {
         .dump           =       pfifo_fast_dump,
         .owner          =       THIS_MODULE,
 };
-EXPORT_SYMBOL(pfifo_fast_ops);
 
 static struct lock_class_key qdisc_tx_busylock;
 
@@ -583,6 +582,9 @@ struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 {
         struct Qdisc *sch;
 
+        if (!try_module_get(ops->owner))
+                goto errout;
+
         sch = qdisc_alloc(dev_queue, ops);
         if (IS_ERR(sch))
                 goto errout;
@@ -686,7 +688,7 @@ static void attach_one_default_qdisc(struct net_device *dev,
 
         if (dev->tx_queue_len) {
                 qdisc = qdisc_create_dflt(dev_queue,
-                                          &pfifo_fast_ops, TC_H_ROOT);
+                                          default_qdisc_ops, TC_H_ROOT);
                 if (!qdisc) {
                         netdev_info(dev, "activation failed\n");
                         return;
@@ -739,9 +741,8 @@ void dev_activate(struct net_device *dev)
         int need_watchdog;
 
         /* No queueing discipline is attached to device;
-           create default one i.e. pfifo_fast for devices,
-           which need queueing and noqueue_qdisc for
-           virtual interfaces
+         * create default one for devices, which need queueing
+         * and noqueue_qdisc for virtual interfaces
          */
 
         if (dev->qdisc == &noop_qdisc)
diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index 5da78a19ac9a..2e56185736d6 100644
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -57,7 +57,7 @@ static int mq_init(struct Qdisc *sch, struct nlattr *opt)
 
         for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
                 dev_queue = netdev_get_tx_queue(dev, ntx);
-                qdisc = qdisc_create_dflt(dev_queue, &pfifo_fast_ops,
+                qdisc = qdisc_create_dflt(dev_queue, default_qdisc_ops,
                                           TC_H_MAKE(TC_H_MAJ(sch->handle),
                                                     TC_H_MIN(ntx + 1)));
                 if (qdisc == NULL)
diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index accec33c454c..d44c868cb537 100644
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -124,7 +124,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
 
         for (i = 0; i < dev->num_tx_queues; i++) {
                 dev_queue = netdev_get_tx_queue(dev, i);
-                qdisc = qdisc_create_dflt(dev_queue, &pfifo_fast_ops,
+                qdisc = qdisc_create_dflt(dev_queue, default_qdisc_ops,
                                           TC_H_MAKE(TC_H_MAJ(sch->handle),
                                                     TC_H_MIN(i + 1)));
                 if (qdisc == NULL) {