net: sched: gred: dynamically allocate tc_gred_qopt_offload

The tc_gred_qopt_offload structure has grown too big to be on the
stack for 32-bit architectures after recent changes.

net/sched/sch_gred.c:903:13: error: stack frame size (1180) exceeds limit (1024) in 'gred_destroy' [-Werror,-Wframe-larger-than]
net/sched/sch_gred.c:310:13: error: stack frame size (1212) exceeds limit (1024) in 'gred_offload' [-Werror,-Wframe-larger-than]

Use dynamic allocation per qdisc to avoid this.

Fixes: 50dc9a8572aa ("net: sched: Merge Qdisc::bstats and Qdisc::cpu_bstats data types")
Fixes: 67c9e6270f30 ("net: sched: Protect Qdisc::bstats with u64_stats")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20211026100711.nalhttf6mbe6sudx@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
index 72de08e..1073c76 100644 (file)
--- a/net/sched/sch_gred.c
+++ b/net/sched/sch_gred.c
@@ -56,6 +56,7 @@ struct gred_sched {
        u32             DPs;
        u32             def;
        struct red_vars wred_set;
+       struct tc_gred_qopt_offload *opt;
 };
 
 static inline int gred_wred_mode(struct gred_sched *table)
@@ -311,42 +312,43 @@ static void gred_offload(struct Qdisc *sch, enum tc_gred_command command)
 {
        struct gred_sched *table = qdisc_priv(sch);
        struct net_device *dev = qdisc_dev(sch);
-       struct tc_gred_qopt_offload opt = {
-               .command        = command,
-               .handle         = sch->handle,
-               .parent         = sch->parent,
-       };
+       struct tc_gred_qopt_offload *opt = table->opt;
 
        if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
                return;
 
+       memset(opt, 0, sizeof(*opt));
+       opt->command = command;
+       opt->handle = sch->handle;
+       opt->parent = sch->parent;
+
        if (command == TC_GRED_REPLACE) {
                unsigned int i;
 
-               opt.set.grio_on = gred_rio_mode(table);
-               opt.set.wred_on = gred_wred_mode(table);
-               opt.set.dp_cnt = table->DPs;
-               opt.set.dp_def = table->def;
+               opt->set.grio_on = gred_rio_mode(table);
+               opt->set.wred_on = gred_wred_mode(table);
+               opt->set.dp_cnt = table->DPs;
+               opt->set.dp_def = table->def;
 
                for (i = 0; i < table->DPs; i++) {
                        struct gred_sched_data *q = table->tab[i];
 
                        if (!q)
                                continue;
-                       opt.set.tab[i].present = true;
-                       opt.set.tab[i].limit = q->limit;
-                       opt.set.tab[i].prio = q->prio;
-                       opt.set.tab[i].min = q->parms.qth_min >> q->parms.Wlog;
-                       opt.set.tab[i].max = q->parms.qth_max >> q->parms.Wlog;
-                       opt.set.tab[i].is_ecn = gred_use_ecn(q);
-                       opt.set.tab[i].is_harddrop = gred_use_harddrop(q);
-                       opt.set.tab[i].probability = q->parms.max_P;
-                       opt.set.tab[i].backlog = &q->backlog;
+                       opt->set.tab[i].present = true;
+                       opt->set.tab[i].limit = q->limit;
+                       opt->set.tab[i].prio = q->prio;
+                       opt->set.tab[i].min = q->parms.qth_min >> q->parms.Wlog;
+                       opt->set.tab[i].max = q->parms.qth_max >> q->parms.Wlog;
+                       opt->set.tab[i].is_ecn = gred_use_ecn(q);
+                       opt->set.tab[i].is_harddrop = gred_use_harddrop(q);
+                       opt->set.tab[i].probability = q->parms.max_P;
+                       opt->set.tab[i].backlog = &q->backlog;
                }
-               opt.set.qstats = &sch->qstats;
+               opt->set.qstats = &sch->qstats;
        }
 
-       dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_GRED, &opt);
+       dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_GRED, opt);
 }
 
 static int gred_offload_dump_stats(struct Qdisc *sch)
@@ -731,6 +733,7 @@ err_unlock_free:
 static int gred_init(struct Qdisc *sch, struct nlattr *opt,
                     struct netlink_ext_ack *extack)
 {
+       struct gred_sched *table = qdisc_priv(sch);
        struct nlattr *tb[TCA_GRED_MAX + 1];
        int err;
 
@@ -754,6 +757,12 @@ static int gred_init(struct Qdisc *sch, struct nlattr *opt,
                sch->limit = qdisc_dev(sch)->tx_queue_len
                             * psched_mtu(qdisc_dev(sch));
 
+       if (qdisc_dev(sch)->netdev_ops->ndo_setup_tc) {
+               table->opt = kzalloc(sizeof(*table->opt), GFP_KERNEL);
+               if (!table->opt)
+                       return -ENOMEM;
+       }
+
        return gred_change_table_def(sch, tb[TCA_GRED_DPS], extack);
 }
 
@@ -910,6 +919,7 @@ static void gred_destroy(struct Qdisc *sch)
                        gred_destroy_vq(table->tab[i]);
        }
        gred_offload(sch, TC_GRED_DESTROY);
+       kfree(table->opt);
 }
 
 static struct Qdisc_ops gred_qdisc_ops __read_mostly = {