[PKT_SCHED]: GRED: Use central VQ change procedure

Introduces a function gred_change_vq() acting as a central point
to change VQ parameters. Fixes priority inheritance in rio mode
when the default DP equals 0. Adds proper locking during changes.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
index b04b07f..ca6cb27 100644 (file)
--- a/net/sched/sch_gred.c
+++ b/net/sched/sch_gred.c
@@ -58,6 +58,8 @@
 #define D2PRINTK(format,args...)
 #endif
 
+#define GRED_DEF_PRIO (MAX_DPs / 2)
+
 struct gred_sched_data;
 struct gred_sched;
 
@@ -432,77 +434,102 @@ static inline int gred_change_table_def(struct Qdisc *sch, struct rtattr *dps)
        return 0;
 }
 
-static int gred_change(struct Qdisc *sch, struct rtattr *opt)
+static inline int gred_change_vq(struct Qdisc *sch, int dp,
+                                struct tc_gred_qopt *ctl, int prio, u8 *stab)
 {
        struct gred_sched *table = qdisc_priv(sch);
        struct gred_sched_data *q;
+
+       if (table->tab[dp] == NULL) {
+               table->tab[dp] = kmalloc(sizeof(*q), GFP_KERNEL);
+               if (table->tab[dp] == NULL)
+                       return -ENOMEM;
+               memset(table->tab[dp], 0, sizeof(*q));
+       }
+
+       q = table->tab[dp];
+       q->DP = dp;
+       q->prio = prio;
+
+       q->Wlog = ctl->Wlog;
+       q->Plog = ctl->Plog;
+       q->limit = ctl->limit;
+       q->Scell_log = ctl->Scell_log;
+       q->Rmask = ctl->Plog < 32 ? ((1<<ctl->Plog) - 1) : ~0UL;
+       q->Scell_max = (255<<q->Scell_log);
+       q->qth_min = ctl->qth_min<<ctl->Wlog;
+       q->qth_max = ctl->qth_max<<ctl->Wlog;
+       q->qave=0;
+       q->backlog=0;
+       q->qcount = -1;
+       q->other=0;
+       q->forced=0;
+       q->pdrop=0;
+       q->early=0;
+
+       PSCHED_SET_PASTPERFECT(q->qidlestart);
+       memcpy(q->Stab, stab, 256);
+
+       return 0;
+}
+
+static int gred_change(struct Qdisc *sch, struct rtattr *opt)
+{
+       struct gred_sched *table = qdisc_priv(sch);
        struct tc_gred_qopt *ctl;
-       struct rtattr *tb[TCA_GRED_STAB];
+       struct rtattr *tb[TCA_GRED_MAX];
+       int err = -EINVAL, prio = GRED_DEF_PRIO;
+       u8 *stab;
 
-       if (opt == NULL || rtattr_parse_nested(tb, TCA_GRED_STAB, opt))
+       if (opt == NULL || rtattr_parse_nested(tb, TCA_GRED_MAX, opt))
                return -EINVAL;
 
        if (tb[TCA_GRED_PARMS-1] == NULL && tb[TCA_GRED_STAB-1] == NULL)
-               return gred_change_table_def(sch, tb[TCA_GRED_DPS-1]);
+               return gred_change_table_def(sch, opt);
 
-       if (!table->DPs || tb[TCA_GRED_PARMS-1] == 0 || tb[TCA_GRED_STAB-1] == 0 ||
-               RTA_PAYLOAD(tb[TCA_GRED_PARMS-1]) < sizeof(*ctl) ||
-               RTA_PAYLOAD(tb[TCA_GRED_STAB-1]) < 256)
-                       return -EINVAL;
+       if (tb[TCA_GRED_PARMS-1] == NULL ||
+           RTA_PAYLOAD(tb[TCA_GRED_PARMS-1]) < sizeof(*ctl) ||
+           tb[TCA_GRED_STAB-1] == NULL ||
+           RTA_PAYLOAD(tb[TCA_GRED_STAB-1]) < 256)
+               return -EINVAL;
 
        ctl = RTA_DATA(tb[TCA_GRED_PARMS-1]);
+       stab = RTA_DATA(tb[TCA_GRED_STAB-1]);
 
        if (ctl->DP >= table->DPs)
-               return -EINVAL;
-       
-       if (table->tab[ctl->DP] == NULL) {
-               table->tab[ctl->DP]=kmalloc(sizeof(struct gred_sched_data),
-                                           GFP_KERNEL);
-               if (NULL == table->tab[ctl->DP])
-                       return -ENOMEM;
-               memset(table->tab[ctl->DP], 0, (sizeof(struct gred_sched_data)));
-       }
-       q= table->tab[ctl->DP]; 
+               goto errout;
 
        if (gred_rio_mode(table)) {
-               if (ctl->prio <=0) {
-                       if (table->def && table->tab[table->def]) {
-                               DPRINTK("\nGRED: DP %u does not have a prio"
-                                       "setting default to %d\n",ctl->DP,
-                                       table->tab[table->def]->prio);
-                               q->prio=table->tab[table->def]->prio;
-                       } else { 
-                               DPRINTK("\nGRED: DP %u does not have a prio"
-                                       " setting default to 8\n",ctl->DP);
-                               q->prio=8;
-                       }
-               } else {
-                       q->prio=ctl->prio;
-               }
-       } else {
-               q->prio=8;
+               if (ctl->prio == 0) {
+                       int def_prio = GRED_DEF_PRIO;
+
+                       if (table->tab[table->def])
+                               def_prio = table->tab[table->def]->prio;
+
+                       printk(KERN_DEBUG "GRED: DP %u does not have a prio "
+                              "setting default to %d\n", ctl->DP, def_prio);
+
+                       prio = def_prio;
+               } else
+                       prio = ctl->prio;
        }
 
+       sch_tree_lock(sch);
 
-       q->DP=ctl->DP;
-       q->Wlog = ctl->Wlog;
-       q->Plog = ctl->Plog;
-       q->limit = ctl->limit;
-       q->Scell_log = ctl->Scell_log;
-       q->Rmask = ctl->Plog < 32 ? ((1<<ctl->Plog) - 1) : ~0UL;
-       q->Scell_max = (255<<q->Scell_log);
-       q->qth_min = ctl->qth_min<<ctl->Wlog;
-       q->qth_max = ctl->qth_max<<ctl->Wlog;
-       q->qave=0;
-       q->backlog=0;
-       q->qcount = -1;
-       q->other=0;
-       q->forced=0;
-       q->pdrop=0;
-       q->early=0;
+       err = gred_change_vq(sch, ctl->DP, ctl, prio, stab);
+       if (err < 0)
+               goto errout_locked;
 
-       PSCHED_SET_PASTPERFECT(q->qidlestart);
-       memcpy(q->Stab, RTA_DATA(tb[TCA_GRED_STAB-1]), 256);
+       if (table->tab[table->def] == NULL) {
+               if (gred_rio_mode(table))
+                       prio = table->tab[ctl->DP]->prio;
+
+               err = gred_change_vq(sch, table->def, ctl, prio, stab);
+               if (err < 0)
+                       goto errout_locked;
+       }
+
+       table->initd = 1;
 
        if (gred_rio_mode(table)) {
                gred_disable_wred_mode(table);
@@ -510,44 +537,12 @@ static int gred_change(struct Qdisc *sch, struct rtattr *opt)
                        gred_enable_wred_mode(table);
        }
 
-       if (!table->initd) {
-               table->initd=1;
-               /* 
-               the first entry also goes into the default until
-               over-written 
-               */
-
-               if (table->tab[table->def] == NULL) {
-                       table->tab[table->def]=
-                               kmalloc(sizeof(struct gred_sched_data), GFP_KERNEL);
-                       if (NULL == table->tab[table->def])
-                               return -ENOMEM;
-
-                       memset(table->tab[table->def], 0,
-                              (sizeof(struct gred_sched_data)));
-               }
-               q= table->tab[table->def]; 
-               q->DP=table->def;
-               q->Wlog = ctl->Wlog;
-               q->Plog = ctl->Plog;
-               q->limit = ctl->limit;
-               q->Scell_log = ctl->Scell_log;
-               q->Rmask = ctl->Plog < 32 ? ((1<<ctl->Plog) - 1) : ~0UL;
-               q->Scell_max = (255<<q->Scell_log);
-               q->qth_min = ctl->qth_min<<ctl->Wlog;
-               q->qth_max = ctl->qth_max<<ctl->Wlog;
-
-               if (gred_rio_mode(table))
-                       q->prio=table->tab[ctl->DP]->prio;
-               else
-                       q->prio=8;
-
-               q->qcount = -1;
-               PSCHED_SET_PASTPERFECT(q->qidlestart);
-               memcpy(q->Stab, RTA_DATA(tb[TCA_GRED_STAB-1]), 256);
-       }
-       return 0;
+       err = 0;
 
+errout_locked:
+       sch_tree_unlock(sch);
+errout:
+       return err;
 }
 
 static int gred_init(struct Qdisc *sch, struct rtattr *opt)