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SubjectRe: [PATCH net-next v3] net: sched: gred: dynamically allocate tc_gred_qopt_offload
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10/26/21 1:07 PM, Sebastian Andrzej Siewior пишет:
> From: Arnd Bergmann <arnd@arndb.de>
>
> 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>
> ---
> v2…v3:
> - drop not needed return statement in gred_offload() (Jakub)
> - use kzalloc(sizeof(*table->opt) in gred_init() (Eric)
> - Make the allocation conditional on ->ndo_setup_tc (Jakub).
>
> net/sched/sch_gred.c | 50 ++++++++++++++++++++++++++------------------
> 1 file changed, 30 insertions(+), 20 deletions(-)
>
> diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c
> index 72de08ef8335e..1073c76d05c45 100644
> --- 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));

It's zeroed in kzalloc()

> + 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 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt,
> 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 = {
>

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