codel: generalize the implementation

This strips out qdisc specific bits from the code
and makes it slightly more reusable. Codel will be
used by wireless/mac80211 in the future.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/codel.h b/include/net/codel.h
index d168aca115ccf0ff4c4ca98107327c533314c618..06ac687b490972cef1bdb8795289a67b6e87f23e 100644 (file)
--- a/include/net/codel.h
+++ b/include/net/codel.h
@@ -176,12 +176,10 @@ struct codel_stats {
 
 #define CODEL_DISABLED_THRESHOLD INT_MAX
 
-static void codel_params_init(struct codel_params *params,
-                             const struct Qdisc *sch)
+static void codel_params_init(struct codel_params *params)
 {
        params->interval = MS2TIME(100);
        params->target = MS2TIME(5);
-       params->mtu = psched_mtu(qdisc_dev(sch));
        params->ce_threshold = CODEL_DISABLED_THRESHOLD;
        params->ecn = false;
 }
@@ -226,28 +224,38 @@ static codel_time_t codel_control_law(codel_time_t t,
        return t + reciprocal_scale(interval, rec_inv_sqrt << REC_INV_SQRT_SHIFT);
 }
 
+typedef u32 (*codel_skb_len_t)(const struct sk_buff *skb);
+typedef codel_time_t (*codel_skb_time_t)(const struct sk_buff *skb);
+typedef void (*codel_skb_drop_t)(struct sk_buff *skb, void *ctx);
+typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars,
+                                               void *ctx);
+
 static bool codel_should_drop(const struct sk_buff *skb,
-                             struct Qdisc *sch,
+                             void *ctx,
                              struct codel_vars *vars,
                              struct codel_params *params,
                              struct codel_stats *stats,
+                             codel_skb_len_t skb_len_func,
+                             codel_skb_time_t skb_time_func,
+                             u32 *backlog,
                              codel_time_t now)
 {
        bool ok_to_drop;
+       u32 skb_len;
 
        if (!skb) {
                vars->first_above_time = 0;
                return false;
        }
 
-       vars->ldelay = now - codel_get_enqueue_time(skb);
-       sch->qstats.backlog -= qdisc_pkt_len(skb);
+       skb_len = skb_len_func(skb);
+       vars->ldelay = now - skb_time_func(skb);
 
-       if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket))
-               stats->maxpacket = qdisc_pkt_len(skb);
+       if (unlikely(skb_len > stats->maxpacket))
+               stats->maxpacket = skb_len;
 
        if (codel_time_before(vars->ldelay, params->target) ||
-           sch->qstats.backlog <= params->mtu) {
+           *backlog <= params->mtu) {
                /* went below - stay below for at least interval */
                vars->first_above_time = 0;
                return false;
@@ -264,16 +272,17 @@ static bool codel_should_drop(const struct sk_buff *skb,
        return ok_to_drop;
 }
 
-typedef struct sk_buff * (*codel_skb_dequeue_t)(struct codel_vars *vars,
-                                               struct Qdisc *sch);
-
-static struct sk_buff *codel_dequeue(struct Qdisc *sch,
+static struct sk_buff *codel_dequeue(void *ctx,
+                                    u32 *backlog,
                                     struct codel_params *params,
                                     struct codel_vars *vars,
                                     struct codel_stats *stats,
+                                    codel_skb_len_t skb_len_func,
+                                    codel_skb_time_t skb_time_func,
+                                    codel_skb_drop_t drop_func,
                                     codel_skb_dequeue_t dequeue_func)
 {
-       struct sk_buff *skb = dequeue_func(vars, sch);
+       struct sk_buff *skb = dequeue_func(vars, ctx);
        codel_time_t now;
        bool drop;
 
@@ -282,7 +291,8 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
                return skb;
        }
        now = codel_get_time();
-       drop = codel_should_drop(skb, sch, vars, params, stats, now);
+       drop = codel_should_drop(skb, ctx, vars, params, stats,
+                                skb_len_func, skb_time_func, backlog, now);
        if (vars->dropping) {
                if (!drop) {
                        /* sojourn time below target - leave dropping state */
@@ -310,12 +320,15 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
                                                                  vars->rec_inv_sqrt);
                                        goto end;
                                }
-                               stats->drop_len += qdisc_pkt_len(skb);
-                               qdisc_drop(skb, sch);
+                               stats->drop_len += skb_len_func(skb);
+                               drop_func(skb, ctx);
                                stats->drop_count++;
-                               skb = dequeue_func(vars, sch);
-                               if (!codel_should_drop(skb, sch,
-                                                      vars, params, stats, now)) {
+                               skb = dequeue_func(vars, ctx);
+                               if (!codel_should_drop(skb, ctx,
+                                                      vars, params, stats,
+                                                      skb_len_func,
+                                                      skb_time_func,
+                                                      backlog, now)) {
                                        /* leave dropping state */
                                        vars->dropping = false;
                                } else {
@@ -333,13 +346,14 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
                if (params->ecn && INET_ECN_set_ce(skb)) {
                        stats->ecn_mark++;
                } else {
-                       stats->drop_len += qdisc_pkt_len(skb);
-                       qdisc_drop(skb, sch);
+                       stats->drop_len += skb_len_func(skb);
+                       drop_func(skb, ctx);
                        stats->drop_count++;
 
-                       skb = dequeue_func(vars, sch);
-                       drop = codel_should_drop(skb, sch, vars, params,
-                                                stats, now);
+                       skb = dequeue_func(vars, ctx);
+                       drop = codel_should_drop(skb, ctx, vars, params,
+                                                stats, skb_len_func,
+                                                skb_time_func, backlog, now);
                }
                vars->dropping = true;
                /* if min went above target close to when we last went below it

diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c
index 9b7e2980ee5c64c18477d003957fedd10c1718d5..512a94abe351450fc385a213184f1ab9cc9d6484 100644 (file)
--- a/net/sched/sch_codel.c
+++ b/net/sched/sch_codel.c
@@ -64,20 +64,33 @@ struct codel_sched_data {
  * to dequeue a packet from queue. Note: backlog is handled in
  * codel, we dont need to reduce it here.
  */
-static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
+static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
 {
+       struct Qdisc *sch = ctx;
        struct sk_buff *skb = __skb_dequeue(&sch->q);
 
+       if (skb)
+               sch->qstats.backlog -= qdisc_pkt_len(skb);
+
        prefetch(&skb->end); /* we'll need skb_shinfo() */
        return skb;
 }
 
+static void drop_func(struct sk_buff *skb, void *ctx)
+{
+       struct Qdisc *sch = ctx;
+
+       qdisc_drop(skb, sch);
+}
+
 static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch)
 {
        struct codel_sched_data *q = qdisc_priv(sch);
        struct sk_buff *skb;
 
-       skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
+       skb = codel_dequeue(sch, &sch->qstats.backlog, &q->params, &q->vars,
+                           &q->stats, qdisc_pkt_len, codel_get_enqueue_time,
+                           drop_func, dequeue_func);
 
        /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
         * or HTB crashes. Defer it for next round.
@@ -173,9 +186,10 @@ static int codel_init(struct Qdisc *sch, struct nlattr *opt)
 
        sch->limit = DEFAULT_CODEL_LIMIT;
 
-       codel_params_init(&q->params, sch);
+       codel_params_init(&q->params);
        codel_vars_init(&q->vars);
        codel_stats_init(&q->stats);
+       q->params.mtu = psched_mtu(qdisc_dev(sch));
 
        if (opt) {
                int err = codel_change(sch, opt);

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index d3fc8f9dd3d464a23f9ea924fc00154a861eda26..dcf7266e6901abac8681b01d732094972c5731d1 100644 (file)
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -220,8 +220,9 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
  * to dequeue a packet from queue. Note: backlog is handled in
  * codel, we dont need to reduce it here.
  */
-static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
+static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
 {
+       struct Qdisc *sch = ctx;
        struct fq_codel_sched_data *q = qdisc_priv(sch);
        struct fq_codel_flow *flow;
        struct sk_buff *skb = NULL;
@@ -231,10 +232,18 @@ static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
                skb = dequeue_head(flow);
                q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
                sch->q.qlen--;
+               sch->qstats.backlog -= qdisc_pkt_len(skb);
        }
        return skb;
 }
 
+static void drop_func(struct sk_buff *skb, void *ctx)
+{
+       struct Qdisc *sch = ctx;
+
+       qdisc_drop(skb, sch);
+}
+
 static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch)
 {
        struct fq_codel_sched_data *q = qdisc_priv(sch);
@@ -263,8 +272,9 @@ begin:
        prev_ecn_mark = q->cstats.ecn_mark;
        prev_backlog = sch->qstats.backlog;
 
-       skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
-                           dequeue);
+       skb = codel_dequeue(sch, &sch->qstats.backlog, &q->cparams,
+                           &flow->cvars, &q->cstats, qdisc_pkt_len,
+                           codel_get_enqueue_time, drop_func, dequeue_func);
 
        flow->dropped += q->cstats.drop_count - prev_drop_count;
        flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
@@ -423,9 +433,10 @@ static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
        q->perturbation = prandom_u32();
        INIT_LIST_HEAD(&q->new_flows);
        INIT_LIST_HEAD(&q->old_flows);
-       codel_params_init(&q->cparams, sch);
+       codel_params_init(&q->cparams);
        codel_stats_init(&q->cstats);
        q->cparams.ecn = true;
+       q->cparams.mtu = psched_mtu(qdisc_dev(sch));
 
        if (opt) {
                int err = fq_codel_change(sch, opt);