4 files changed, 47 insertions, 26 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 1313145e3b86..a07d55e75698 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -273,11 +273,12 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
 
 void qdisc_list_add(struct Qdisc *q)
 {
-        struct Qdisc *root = qdisc_dev(q)->qdisc;
+        if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS)) {
+                struct Qdisc *root = qdisc_dev(q)->qdisc;
 
-        WARN_ON_ONCE(root == &noop_qdisc);
-        if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS))
+                WARN_ON_ONCE(root == &noop_qdisc);
                 list_add_tail(&q->list, &root->list);
+        }
 }
 EXPORT_SYMBOL(qdisc_list_add);
 
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 08ef7a42c0e4..21e251766eb1 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -601,6 +601,7 @@ static int fq_resize(struct Qdisc *sch, u32 log)
 {
         struct fq_sched_data *q = qdisc_priv(sch);
         struct rb_root *array;
+        void *old_fq_root;
         u32 idx;
 
         if (q->fq_root && log == q->fq_trees_log)
@@ -615,13 +616,19 @@ static int fq_resize(struct Qdisc *sch, u32 log)
         for (idx = 0; idx < (1U << log); idx++)
                 array[idx] = RB_ROOT;
 
-        if (q->fq_root) {
-                fq_rehash(q, q->fq_root, q->fq_trees_log, array, log);
-                fq_free(q->fq_root);
-        }
+        sch_tree_lock(sch);
+
+        old_fq_root = q->fq_root;
+        if (old_fq_root)
+                fq_rehash(q, old_fq_root, q->fq_trees_log, array, log);
+
         q->fq_root = array;
         q->fq_trees_log = log;
 
+        sch_tree_unlock(sch);
+
+        fq_free(old_fq_root);
+
         return 0;
 }
 
@@ -697,9 +704,11 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt)
                 q->flow_refill_delay = usecs_to_jiffies(usecs_delay);
         }
 
-        if (!err)
+        if (!err) {
+                sch_tree_unlock(sch);
                 err = fq_resize(sch, fq_log);
-
+                sch_tree_lock(sch);
+        }
         while (sch->q.qlen > sch->limit) {
                 struct sk_buff *skb = fq_dequeue(sch);
 
diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c
index a255d0200a59..fefeeb73f15f 100644
--- a/net/sched/sch_pie.c
+++ b/net/sched/sch_pie.c
@@ -15,6 +15,11 @@
  *
  * ECN support is added by Naeem Khademi <naeemk@ifi.uio.no>
  * University of Oslo, Norway.
+ *
+ * References:
+ * IETF draft submission: http://tools.ietf.org/html/draft-pan-aqm-pie-00
+ * IEEE  Conference on High Performance Switching and Routing 2013 :
+ * "PIE: A * Lightweight Control Scheme to Address the Bufferbloat Problem"
  */
 
 #include <linux/module.h>
@@ -36,7 +41,7 @@ struct pie_params {
         psched_time_t target;   /* user specified target delay in pschedtime */
         u32 tupdate;            /* timer frequency (in jiffies) */
         u32 limit;              /* number of packets that can be enqueued */
-        u32 alpha;              /* alpha and beta are between -4 and 4 */
+        u32 alpha;              /* alpha and beta are between 0 and 32 */
         u32 beta;               /* and are used for shift relative to 1 */
         bool ecn;               /* true if ecn is enabled */
         bool bytemode;          /* to scale drop early prob based on pkt size */
@@ -326,10 +331,16 @@ static void calculate_probability(struct Qdisc *sch)
         if (qdelay == 0 && qlen != 0)
                 update_prob = false;
 
-        /* Add ranges for alpha and beta, more aggressive for high dropping
-         * mode and gentle steps for light dropping mode
-         * In light dropping mode, take gentle steps; in medium dropping mode,
-         * take medium steps; in high dropping mode, take big steps.
+        /* In the algorithm, alpha and beta are between 0 and 2 with typical
+         * value for alpha as 0.125. In this implementation, we use values 0-32
+         * passed from user space to represent this. Also, alpha and beta have
+         * unit of HZ and need to be scaled before they can used to update
+         * probability. alpha/beta are updated locally below by 1) scaling them
+         * appropriately 2) scaling down by 16 to come to 0-2 range.
+         * Please see paper for details.
+         *
+         * We scale alpha and beta differently depending on whether we are in
+         * light, medium or high dropping mode.
          */
         if (q->vars.prob < MAX_PROB / 100) {
                 alpha =
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 1cb413fead89..4f505a006896 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -334,18 +334,6 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
                         qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate,
                                                       tb[TCA_TBF_PTAB]));
 
-        if (q->qdisc != &noop_qdisc) {
-                err = fifo_set_limit(q->qdisc, qopt->limit);
-                if (err)
-                        goto done;
-        } else if (qopt->limit > 0) {
-                child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit);
-                if (IS_ERR(child)) {
-                        err = PTR_ERR(child);
-                        goto done;
-                }
-        }
-
         buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U);
         mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U);
 
@@ -390,6 +378,18 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
                 goto done;
         }
 
+        if (q->qdisc != &noop_qdisc) {
+                err = fifo_set_limit(q->qdisc, qopt->limit);
+                if (err)
+                        goto done;
+        } else if (qopt->limit > 0) {
+                child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit);
+                if (IS_ERR(child)) {
+                        err = PTR_ERR(child);
+                        goto done;
+                }
+        }
+
         sch_tree_lock(sch);
         if (child) {
                 qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);