Re: [RFC,net-next 2/9] net: qos: introduce a gate control flow action

[Cong Wang]

On Fri, Mar 6, 2020 at 5:14 AM Po Liu <Po.Liu@xxxxxxx> wrote:
> +static int parse_gate_list(struct nlattr *list,
> +                          struct tcf_gate_params *sched,
> +                          struct netlink_ext_ack *extack)
> +{
> +       struct nlattr *n;
> +       int err, rem;
> +       int i = 0;
> +
> +       if (!list)
> +               return -EINVAL;
> +
> +       nla_for_each_nested(n, list, rem) {
> +               struct tcfg_gate_entry *entry;
> +
> +               if (nla_type(n) != TCA_GATE_ONE_ENTRY) {
> +                       NL_SET_ERR_MSG(extack, "Attribute isn't type 'entry'");
> +                       continue;
> +               }
> +
> +               entry = kzalloc(sizeof(*entry), GFP_KERNEL);
> +               if (!entry) {
> +                       NL_SET_ERR_MSG(extack, "Not enough memory for entry");
> +                       return -ENOMEM;
> +               }

You need to free all previous allocated entries on this list
when an error happens, right?


> +
> +               err = parse_gate_entry(n, entry, i, extack);
> +               if (err < 0) {
> +                       kfree(entry);
> +                       return err;
> +               }
> +
> +               list_add_tail(&entry->list, &sched->entries);
> +               i++;
> +       }
> +
> +       sched->num_entries = i;
> +
> +       return i;
> +}
> +
> +static int tcf_gate_init(struct net *net, struct nlattr *nla,
> +                        struct nlattr *est, struct tc_action **a,
> +                        int ovr, int bind, bool rtnl_held,
> +                        struct tcf_proto *tp, u32 flags,
> +                        struct netlink_ext_ack *extack)
> +{
> +       struct tc_action_net *tn = net_generic(net, gate_net_id);
> +       enum tk_offsets tk_offset = TK_OFFS_TAI;
> +       struct nlattr *tb[TCA_GATE_MAX + 1];
> +       struct tcf_chain *goto_ch = NULL;
> +       struct tcfg_gate_entry *next;
> +       struct tcf_gate_params *p;
> +       struct gate_action *gact;
> +       s32 clockid = CLOCK_TAI;
> +       struct tc_gate *parm;
> +       struct tcf_gate *g;
> +       int ret = 0, err;
> +       u64 basetime = 0;
> +       u32 gflags = 0;
> +       s32 prio = -1;
> +       ktime_t start;
> +       u32 index;
> +
> +       if (!nla)
> +               return -EINVAL;
> +
> +       err = nla_parse_nested_deprecated(tb, TCA_GATE_MAX,
> +                                         nla, gate_policy, NULL);
> +       if (err < 0)
> +               return err;
> +
> +       if (!tb[TCA_GATE_PARMS])
> +               return -EINVAL;
> +       parm = nla_data(tb[TCA_GATE_PARMS]);
> +       index = parm->index;
> +       err = tcf_idr_check_alloc(tn, &index, a, bind);
> +       if (err < 0)
> +               return err;
> +
> +       if (err && bind)
> +               return 0;
> +
> +       if (!err) {
> +               ret = tcf_idr_create_from_flags(tn, index, est, a,
> +                                               &act_gate_ops, bind, flags);
> +               if (ret) {
> +                       tcf_idr_cleanup(tn, index);
> +                       return ret;
> +               }
> +
> +               ret = ACT_P_CREATED;
> +       } else if (!ovr) {
> +               tcf_idr_release(*a, bind);
> +               return -EEXIST;
> +       }
> +
> +       if (tb[TCA_GATE_PRIORITY])
> +               prio = nla_get_s32(tb[TCA_GATE_PRIORITY]);
> +
> +       if (tb[TCA_GATE_BASE_TIME])
> +               basetime = nla_get_u64(tb[TCA_GATE_BASE_TIME]);
> +
> +       if (tb[TCA_GATE_FLAGS])
> +               gflags = nla_get_u32(tb[TCA_GATE_FLAGS]);
> +
> +       if (tb[TCA_GATE_CLOCKID]) {
> +               clockid = nla_get_s32(tb[TCA_GATE_CLOCKID]);
> +               switch (clockid) {
> +               case CLOCK_REALTIME:
> +                       tk_offset = TK_OFFS_REAL;
> +                       break;
> +               case CLOCK_MONOTONIC:
> +                       tk_offset = TK_OFFS_MAX;
> +                       break;
> +               case CLOCK_BOOTTIME:
> +                       tk_offset = TK_OFFS_BOOT;
> +                       break;
> +               case CLOCK_TAI:
> +                       tk_offset = TK_OFFS_TAI;
> +                       break;
> +               default:
> +                       NL_SET_ERR_MSG(extack, "Invalid 'clockid'");
> +                       goto release_idr;
> +               }
> +       }
> +
> +       err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
> +       if (err < 0)
> +               goto release_idr;
> +
> +       g = to_gate(*a);
> +
> +       gact = kzalloc(sizeof(*gact), GFP_KERNEL);
> +       if (!gact) {
> +               err = -ENOMEM;
> +               goto put_chain;
> +       }
> +
> +       p = get_gate_param(gact);
> +
> +       INIT_LIST_HEAD(&p->entries);
> +       if (tb[TCA_GATE_ENTRY_LIST]) {
> +               err = parse_gate_list(tb[TCA_GATE_ENTRY_LIST], p, extack);
> +               if (err < 0)
> +                       goto release_mem;
> +       }
> +
> +       if (tb[TCA_GATE_CYCLE_TIME]) {
> +               p->tcfg_cycletime = nla_get_u64(tb[TCA_GATE_CYCLE_TIME]);
> +       } else {
> +               struct tcfg_gate_entry *entry;
> +               ktime_t cycle = 0;
> +
> +               list_for_each_entry(entry, &p->entries, list)
> +                       cycle = ktime_add_ns(cycle, entry->interval);
> +               p->tcfg_cycletime = cycle;
> +       }
> +
> +       if (tb[TCA_GATE_CYCLE_TIME_EXT])
> +               p->tcfg_cycletime_ext =
> +                       nla_get_u64(tb[TCA_GATE_CYCLE_TIME_EXT]);
> +
> +       p->tcfg_priority = prio;
> +       p->tcfg_basetime = basetime;
> +       p->tcfg_clockid = clockid;
> +       p->tcfg_flags = gflags;
> +
> +       gact->tk_offset = tk_offset;
> +       spin_lock_init(&gact->entry_lock);
> +       hrtimer_init(&gact->hitimer, clockid, HRTIMER_MODE_ABS);
> +       gact->hitimer.function = gate_timer_func;
> +
> +       err = gate_get_start_time(gact, &start);
> +       if (err < 0) {
> +               NL_SET_ERR_MSG(extack,
> +                              "Internal error: failed get start time");
> +               goto release_mem;
> +       }
> +
> +       gact->current_close_time = start;
> +       gact->current_gate_status = GATE_ACT_GATE_OPEN | GATE_ACT_PENDING;
> +
> +       next = list_first_entry(&p->entries, struct tcfg_gate_entry, list);
> +       rcu_assign_pointer(gact->next_entry, next);
> +
> +       gate_start_timer(gact, start);
> +
> +       spin_lock_bh(&g->tcf_lock);
> +       goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
> +       gact = rcu_replace_pointer(g->actg, gact,
> +                                  lockdep_is_held(&g->tcf_lock));
> +       spin_unlock_bh(&g->tcf_lock);
> +
> +       if (goto_ch)
> +               tcf_chain_put_by_act(goto_ch);
> +       if (gact)
> +               kfree_rcu(gact, rcu);
> +
> +       if (ret == ACT_P_CREATED)
> +               tcf_idr_insert(tn, *a);
> +       return ret;
> +
> +release_mem:
> +       kfree_rcu(gact, rcu);

No need to bother RCU for an error path, right?

Thanks.