net: sched: introduce and use qdisc tree flush/purge helpers

The same code to flush qdisc tree and purge the qdisc queue
is duplicated in many places and in most cases it does not
respect NOLOCK qdisc: the global backlog len is used and the
per CPU values are ignored.

This change addresses the above, factoring-out the relevant
code and using the helpers introduced by the previous patch
to fetch the correct backlog len.

Fixes: c5ad119fb6c0 ("net: sched: pfifo_fast use skb_array")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

10 files changed, 16 insertions, 66 deletions

diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 651879c1b655..114b9048ea7e 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1667,17 +1667,13 @@ static int cbq_delete(struct Qdisc *sch, unsigned long arg)
 {
         struct cbq_sched_data *q = qdisc_priv(sch);
         struct cbq_class *cl = (struct cbq_class *)arg;
-        unsigned int qlen, backlog;
 
         if (cl->filters || cl->children || cl == &q->link)
                 return -EBUSY;
 
         sch_tree_lock(sch);
 
-        qlen = cl->q->q.qlen;
-        backlog = cl->q->qstats.backlog;
-        qdisc_reset(cl->q);
-        qdisc_tree_reduce_backlog(cl->q, qlen, backlog);
+        qdisc_purge_queue(cl->q);
 
         if (cl->next_alive)
                 cbq_deactivate_class(cl);
diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index 8a181591b0ea..430df9a55ec4 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -50,15 +50,6 @@ static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
         return container_of(clc, struct drr_class, common);
 }
 
-static void drr_purge_queue(struct drr_class *cl)
-{
-        unsigned int len = cl->qdisc->q.qlen;
-        unsigned int backlog = cl->qdisc->qstats.backlog;
-
-        qdisc_reset(cl->qdisc);
-        qdisc_tree_reduce_backlog(cl->qdisc, len, backlog);
-}
-
 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
         [TCA_DRR_QUANTUM]       = { .type = NLA_U32 },
 };
@@ -167,7 +158,7 @@ static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
 
         sch_tree_lock(sch);
 
-        drr_purge_queue(cl);
+        qdisc_purge_queue(cl->qdisc);
         qdisc_class_hash_remove(&q->clhash, &cl->common);
 
         sch_tree_unlock(sch);
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index a946a419d717..d2ab463f22ae 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -845,16 +845,6 @@ qdisc_peek_len(struct Qdisc *sch)
 }
 
 static void
-hfsc_purge_queue(struct Qdisc *sch, struct hfsc_class *cl)
-{
-        unsigned int len = cl->qdisc->q.qlen;
-        unsigned int backlog = cl->qdisc->qstats.backlog;
-
-        qdisc_reset(cl->qdisc);
-        qdisc_tree_reduce_backlog(cl->qdisc, len, backlog);
-}
-
-static void
 hfsc_adjust_levels(struct hfsc_class *cl)
 {
         struct hfsc_class *p;
@@ -1076,7 +1066,7 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
         qdisc_class_hash_insert(&q->clhash, &cl->cl_common);
         list_add_tail(&cl->siblings, &parent->children);
         if (parent->level == 0)
-                hfsc_purge_queue(sch, parent);
+                qdisc_purge_queue(parent->qdisc);
         hfsc_adjust_levels(parent);
         sch_tree_unlock(sch);
 
@@ -1112,7 +1102,7 @@ hfsc_delete_class(struct Qdisc *sch, unsigned long arg)
         list_del(&cl->siblings);
         hfsc_adjust_levels(cl->cl_parent);
 
-        hfsc_purge_queue(sch, cl);
+        qdisc_purge_queue(cl->qdisc);
         qdisc_class_hash_remove(&q->clhash, &cl->cl_common);
 
         sch_tree_unlock(sch);
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index ed92836f528a..2f9883b196e8 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1269,13 +1269,8 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg)
 
         sch_tree_lock(sch);
 
-        if (!cl->level) {
-                unsigned int qlen = cl->leaf.q->q.qlen;
-                unsigned int backlog = cl->leaf.q->qstats.backlog;
-
-                qdisc_reset(cl->leaf.q);
-                qdisc_tree_reduce_backlog(cl->leaf.q, qlen, backlog);
-        }
+        if (!cl->level)
+                qdisc_purge_queue(cl->leaf.q);
 
         /* delete from hash and active; remainder in destroy_class */
         qdisc_class_hash_remove(&q->clhash, &cl->common);
@@ -1403,12 +1398,8 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
                                           classid, NULL);
                 sch_tree_lock(sch);
                 if (parent && !parent->level) {
-                        unsigned int qlen = parent->leaf.q->q.qlen;
-                        unsigned int backlog = parent->leaf.q->qstats.backlog;
-
                         /* turn parent into inner node */
-                        qdisc_reset(parent->leaf.q);
-                        qdisc_tree_reduce_backlog(parent->leaf.q, qlen, backlog);
+                        qdisc_purge_queue(parent->leaf.q);
                         qdisc_put(parent->leaf.q);
                         if (parent->prio_activity)
                                 htb_deactivate(q, parent);
diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c
index 53c918a11378..35b03ae08e0f 100644
--- a/net/sched/sch_multiq.c
+++ b/net/sched/sch_multiq.c
@@ -201,9 +201,9 @@ static int multiq_tune(struct Qdisc *sch, struct nlattr *opt,
         for (i = q->bands; i < q->max_bands; i++) {
                 if (q->queues[i] != &noop_qdisc) {
                         struct Qdisc *child = q->queues[i];
+
                         q->queues[i] = &noop_qdisc;
-                        qdisc_tree_reduce_backlog(child, child->q.qlen,
-                                                  child->qstats.backlog);
+                        qdisc_tree_flush_backlog(child);
                         qdisc_put(child);
                 }
         }
@@ -225,9 +225,7 @@ static int multiq_tune(struct Qdisc *sch, struct nlattr *opt,
                                         qdisc_hash_add(child, true);
 
                                 if (old != &noop_qdisc) {
-                                        qdisc_tree_reduce_backlog(old,
-                                                                  old->q.qlen,
-                                                                  old->qstats.backlog);
+                                        qdisc_tree_flush_backlog(old);
                                         qdisc_put(old);
                                 }
                                 sch_tree_unlock(sch);
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index dfb06d5bfacc..d519b21535b3 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -216,12 +216,8 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt,
         q->bands = qopt->bands;
         memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 
-        for (i = q->bands; i < oldbands; i++) {
-                struct Qdisc *child = q->queues[i];
-
-                qdisc_tree_reduce_backlog(child, child->q.qlen,
-                                          child->qstats.backlog);
-        }
+        for (i = q->bands; i < oldbands; i++)
+                qdisc_tree_flush_backlog(q->queues[i]);
 
         for (i = oldbands; i < q->bands; i++) {
                 q->queues[i] = queues[i];
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index 9fbda3ec5861..1589364b54da 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -217,15 +217,6 @@ static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid)
         return container_of(clc, struct qfq_class, common);
 }
 
-static void qfq_purge_queue(struct qfq_class *cl)
-{
-        unsigned int len = cl->qdisc->q.qlen;
-        unsigned int backlog = cl->qdisc->qstats.backlog;
-
-        qdisc_reset(cl->qdisc);
-        qdisc_tree_reduce_backlog(cl->qdisc, len, backlog);
-}
-
 static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
         [TCA_QFQ_WEIGHT] = { .type = NLA_U32 },
         [TCA_QFQ_LMAX] = { .type = NLA_U32 },
@@ -551,7 +542,7 @@ static int qfq_delete_class(struct Qdisc *sch, unsigned long arg)
 
         sch_tree_lock(sch);
 
-        qfq_purge_queue(cl);
+        qdisc_purge_queue(cl->qdisc);
         qdisc_class_hash_remove(&q->clhash, &cl->common);
 
         sch_tree_unlock(sch);
diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index 9df9942340ea..4e8c0abf6194 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -233,8 +233,7 @@ static int red_change(struct Qdisc *sch, struct nlattr *opt,
         q->flags = ctl->flags;
         q->limit = ctl->limit;
         if (child) {
-                qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
-                                          q->qdisc->qstats.backlog);
+                qdisc_tree_flush_backlog(q->qdisc);
                 old_child = q->qdisc;
                 q->qdisc = child;
         }
diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c
index bab506b01a32..2419fdb75966 100644
--- a/net/sched/sch_sfb.c
+++ b/net/sched/sch_sfb.c
@@ -521,8 +521,7 @@ static int sfb_change(struct Qdisc *sch, struct nlattr *opt,
                 qdisc_hash_add(child, true);
         sch_tree_lock(sch);
 
-        qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
-                                  q->qdisc->qstats.backlog);
+        qdisc_tree_flush_backlog(q->qdisc);
         qdisc_put(q->qdisc);
         q->qdisc = child;
 
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 7f272a9070c5..f71578dbb9e3 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -391,8 +391,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
 
         sch_tree_lock(sch);
         if (child) {
-                qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
-                                          q->qdisc->qstats.backlog);
+                qdisc_tree_flush_backlog(q->qdisc);
                 qdisc_put(q->qdisc);
                 q->qdisc = child;
         }