[RFC PATCH 05/17] net: sched: a dflt qdisc may be used with per cpu stats

[John Fastabend]

Enable dflt qdisc support for per cpu stats before this patch a dflt
qdisc was required to use the global statistics qstats and bstats.

This adds a static flags field to qdisc_ops that is propagated
into qdisc->flags in qdisc allocate call. This allows the allocation
block to completely allocate the qdisc object so we don't have
dangling allocations after qdisc init.

Signed-off-by: John Fastabend <john.r.fastab...@intel.com>
---
 include/net/sch_generic.h |    1 +
 net/sched/sch_generic.c   |   16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 9531b81..83952af 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -172,6 +172,7 @@ struct Qdisc_ops {
        const struct Qdisc_class_ops    *cl_ops;
        char                    id[IFNAMSIZ];
        int                     priv_size;
+       unsigned int            static_flags;
 
        int                     (*enqueue)(struct sk_buff *skb,
                                           struct Qdisc *sch,
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 2f66b1f..8a03738 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -625,6 +625,19 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
        qdisc_skb_head_init(&sch->q);
        spin_lock_init(&sch->q.lock);
 
+       if (ops->static_flags & TCQ_F_CPUSTATS) {
+               sch->cpu_bstats =
+                       netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
+               if (!sch->cpu_bstats)
+                       goto errout1;
+
+               sch->cpu_qstats = alloc_percpu(struct gnet_stats_queue);
+               if (!sch->cpu_qstats) {
+                       free_percpu(sch->cpu_bstats);
+                       goto errout1;
+               }
+       }
+
        spin_lock_init(&sch->busylock);
        lockdep_set_class(&sch->busylock,
                          dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
@@ -634,6 +647,7 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
                          dev->qdisc_running_key ?: &qdisc_running_key);
 
        sch->ops = ops;
+       sch->flags = ops->static_flags;
        sch->enqueue = ops->enqueue;
        sch->dequeue = ops->dequeue;
        sch->dev_queue = dev_queue;
@@ -641,6 +655,8 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
        atomic_set(&sch->refcnt, 1);
 
        return sch;
+errout1:
+       kfree(p);
 errout:
        return ERR_PTR(err);
 }