pkt_sched: fq: qdisc dismantle fixes

fq_reset() should drops all packets in queue, including
throttled flows.

This patch moves code from fq_destroy() to fq_reset()
to do the cleaning.

fq_change() must stop calling fq_dequeue() if all remaining
packets are from throttled flows.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 37 insertions, 20 deletions

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 32ad015ee8ce..fc6de56a331e 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -285,7 +285,7 @@ static struct fq_flow *fq_classify(struct sk_buff *skb, struct fq_sched_data *q)
 
 
 /* remove one skb from head of flow queue */
-static struct sk_buff *fq_dequeue_head(struct fq_flow *flow)
+static struct sk_buff *fq_dequeue_head(struct Qdisc *sch, struct fq_flow *flow)
 {
         struct sk_buff *skb = flow->head;
 
@@ -293,6 +293,8 @@ static struct sk_buff *fq_dequeue_head(struct fq_flow *flow)
                 flow->head = skb->next;
                 skb->next = NULL;
                 flow->qlen--;
+                sch->qstats.backlog -= qdisc_pkt_len(skb);
+                sch->q.qlen--;
         }
         return skb;
 }
@@ -419,7 +421,7 @@ static struct sk_buff *fq_dequeue(struct Qdisc *sch)
         struct sk_buff *skb;
         struct fq_flow *f;
 
-        skb = fq_dequeue_head(&q->internal);
+        skb = fq_dequeue_head(sch, &q->internal);
         if (skb)
                 goto out;
         fq_check_throttled(q, now);
@@ -449,7 +451,7 @@ begin:
                 goto begin;
         }
 
-        skb = fq_dequeue_head(f);
+        skb = fq_dequeue_head(sch, f);
         if (!skb) {
                 head->first = f->next;
                 /* force a pass through old_flows to prevent starvation */
@@ -490,19 +492,44 @@ begin:
                 }
         }
 out:
-        sch->qstats.backlog -= qdisc_pkt_len(skb);
         qdisc_bstats_update(sch, skb);
-        sch->q.qlen--;
         qdisc_unthrottled(sch);
         return skb;
 }
 
 static void fq_reset(struct Qdisc *sch)
 {
+        struct fq_sched_data *q = qdisc_priv(sch);
+        struct rb_root *root;
         struct sk_buff *skb;
+        struct rb_node *p;
+        struct fq_flow *f;
+        unsigned int idx;
 
-        while ((skb = fq_dequeue(sch)) != NULL)
+        while ((skb = fq_dequeue_head(sch, &q->internal)) != NULL)
                 kfree_skb(skb);
+
+        if (!q->fq_root)
+                return;
+
+        for (idx = 0; idx < (1U << q->fq_trees_log); idx++) {
+                root = &q->fq_root[idx];
+                while ((p = rb_first(root)) != NULL) {
+                        f = container_of(p, struct fq_flow, fq_node);
+                        rb_erase(p, root);
+
+                        while ((skb = fq_dequeue_head(sch, f)) != NULL)
+                                kfree_skb(skb);
+
+                        kmem_cache_free(fq_flow_cachep, f);
+                }
+        }
+        q->new_flows.first      = NULL;
+        q->old_flows.first      = NULL;
+        q->delayed              = RB_ROOT;
+        q->flows                = 0;
+        q->inactive_flows       = 0;
+        q->throttled_flows      = 0;
 }
 
 static void fq_rehash(struct fq_sched_data *q,
@@ -645,6 +672,8 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt)
         while (sch->q.qlen > sch->limit) {
                 struct sk_buff *skb = fq_dequeue(sch);
 
+                if (!skb)
+                        break;
                 kfree_skb(skb);
                 drop_count++;
         }
@@ -657,21 +686,9 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt)
 static void fq_destroy(struct Qdisc *sch)
 {
         struct fq_sched_data *q = qdisc_priv(sch);
-        struct rb_root *root;
-        struct rb_node *p;
-        unsigned int idx;
 
-        if (q->fq_root) {
-                for (idx = 0; idx < (1U << q->fq_trees_log); idx++) {
-                        root = &q->fq_root[idx];
-                        while ((p = rb_first(root)) != NULL) {
-                                rb_erase(p, root);
-                                kmem_cache_free(fq_flow_cachep,
-                                                container_of(p, struct fq_flow, fq_node));
-                        }
-                }
-                kfree(q->fq_root);
-        }
+        fq_reset(sch);
+        kfree(q->fq_root);
         qdisc_watchdog_cancel(&q->watchdog);
 }