Re: [v4,net-next 2/4] net: schedule: add action gate offloading
From: Vlad Buslov
Date: Wed Apr 29 2020 - 13:40:36 EST
On Tue 28 Apr 2020 at 06:34, Po Liu <Po.Liu@xxxxxxx> wrote:
> Add the gate action to the flow action entry. Add the gate parameters to
> the tc_setup_flow_action() queueing to the entries of flow_action_entry
> array provide to the driver.
>
> Signed-off-by: Po Liu <Po.Liu@xxxxxxx>
> ---
> include/net/flow_offload.h | 10 ++++
> include/net/tc_act/tc_gate.h | 113 +++++++++++++++++++++++++++++++++++
> net/sched/cls_api.c | 33 ++++++++++
> 3 files changed, 156 insertions(+)
>
> diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
> index 3619c6acf60f..94a30fe02e6d 100644
> --- a/include/net/flow_offload.h
> +++ b/include/net/flow_offload.h
> @@ -147,6 +147,7 @@ enum flow_action_id {
> FLOW_ACTION_MPLS_PUSH,
> FLOW_ACTION_MPLS_POP,
> FLOW_ACTION_MPLS_MANGLE,
> + FLOW_ACTION_GATE,
> NUM_FLOW_ACTIONS,
> };
>
> @@ -255,6 +256,15 @@ struct flow_action_entry {
> u8 bos;
> u8 ttl;
> } mpls_mangle;
> + struct {
> + u32 index;
> + s32 prio;
> + u64 basetime;
> + u64 cycletime;
> + u64 cycletimeext;
> + u32 num_entries;
> + struct action_gate_entry *entries;
> + } gate;
> };
> struct flow_action_cookie *cookie; /* user defined action cookie */
> };
> diff --git a/include/net/tc_act/tc_gate.h b/include/net/tc_act/tc_gate.h
> index 330ad8b02495..9e698c7d64cd 100644
> --- a/include/net/tc_act/tc_gate.h
> +++ b/include/net/tc_act/tc_gate.h
> @@ -7,6 +7,13 @@
> #include <net/act_api.h>
> #include <linux/tc_act/tc_gate.h>
>
> +struct action_gate_entry {
> + u8 gate_state;
> + u32 interval;
> + s32 ipv;
> + s32 maxoctets;
> +};
> +
> struct tcfg_gate_entry {
> int index;
> u8 gate_state;
> @@ -44,4 +51,110 @@ struct tcf_gate {
>
> #define to_gate(a) ((struct tcf_gate *)a)
>
> +static inline bool is_tcf_gate(const struct tc_action *a)
> +{
> +#ifdef CONFIG_NET_CLS_ACT
> + if (a->ops && a->ops->id == TCA_ID_GATE)
> + return true;
> +#endif
> + return false;
> +}
> +
> +static inline u32 tcf_gate_index(const struct tc_action *a)
> +{
> + return a->tcfa_index;
> +}
> +
> +static inline s32 tcf_gate_prio(const struct tc_action *a)
> +{
> + s32 tcfg_prio;
> +
> + rcu_read_lock();
This action no longer uses rcu, so you don't need protect with
rcu_read_lock() in all these helpers.
> + tcfg_prio = to_gate(a)->param.tcfg_priority;
> + rcu_read_unlock();
> +
> + return tcfg_prio;
> +}
> +
> +static inline u64 tcf_gate_basetime(const struct tc_action *a)
> +{
> + u64 tcfg_basetime;
> +
> + rcu_read_lock();
> + tcfg_basetime = to_gate(a)->param.tcfg_basetime;
> + rcu_read_unlock();
> +
> + return tcfg_basetime;
> +}
> +
> +static inline u64 tcf_gate_cycletime(const struct tc_action *a)
> +{
> + u64 tcfg_cycletime;
> +
> + rcu_read_lock();
> + tcfg_cycletime = to_gate(a)->param.tcfg_cycletime;
> + rcu_read_unlock();
> +
> + return tcfg_cycletime;
> +}
> +
> +static inline u64 tcf_gate_cycletimeext(const struct tc_action *a)
> +{
> + u64 tcfg_cycletimeext;
> +
> + rcu_read_lock();
> + tcfg_cycletimeext = to_gate(a)->param.tcfg_cycletime_ext;
> + rcu_read_unlock();
> +
> + return tcfg_cycletimeext;
> +}
> +
> +static inline u32 tcf_gate_num_entries(const struct tc_action *a)
> +{
> + u32 num_entries;
> +
> + rcu_read_lock();
> + num_entries = to_gate(a)->param.num_entries;
> + rcu_read_unlock();
> +
> + return num_entries;
> +}
> +
> +static inline struct action_gate_entry
> + *tcf_gate_get_list(const struct tc_action *a)
> +{
> + struct action_gate_entry *oe;
> + struct tcf_gate_params *p;
> + struct tcfg_gate_entry *entry;
> + u32 num_entries;
> + int i = 0;
> +
> + rcu_read_lock();
> +
> + p = &to_gate(a)->param;
> + num_entries = p->num_entries;
> +
> + list_for_each_entry(entry, &p->entries, list)
> + i++;
> +
> + if (i != num_entries)
> + return NULL;
> +
> + oe = kzalloc(sizeof(*oe) * num_entries, GFP_KERNEL);
Can't allocate with GFP_KERNEL flag in rcu read blocks, but you don't
need the rcu read lock here anyway. However, tc_setup_flow_action()
calls this function while holding tcfa_lock spinlock, which also
precludes allocating memory with that flag. You can test for such
problems by enabling CONFIG_DEBUG_ATOMIC_SLEEP. To help uncover such
errors all new act APIs and action implementations are usually
accompanied by tdc tests. If you chose to implement such tests you can
look at 6e52fca36c67 ("tc-tests: Add tc action ct tests") for recent
example.
> + if (!oe)
> + return NULL;
This returns without releasing rcu read lock, but as I said before you
probably don't need rcu protection here anyway.
> +
> + i = 0;
> + list_for_each_entry(entry, &p->entries, list) {
> + oe[i].gate_state = entry->gate_state;
> + oe[i].interval = entry->interval;
> + oe[i].ipv = entry->ipv;
> + oe[i].maxoctets = entry->maxoctets;
> + i++;
> + }
> +
> + rcu_read_unlock();
> +
> + return oe;
> +}
> #endif
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 11b683c45c28..7e85c91d0752 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -39,6 +39,7 @@
> #include <net/tc_act/tc_skbedit.h>
> #include <net/tc_act/tc_ct.h>
> #include <net/tc_act/tc_mpls.h>
> +#include <net/tc_act/tc_gate.h>
> #include <net/flow_offload.h>
>
> extern const struct nla_policy rtm_tca_policy[TCA_MAX + 1];
> @@ -3526,6 +3527,27 @@ static void tcf_sample_get_group(struct flow_action_entry *entry,
> #endif
> }
>
> +static void tcf_gate_entry_destructor(void *priv)
> +{
> + struct action_gate_entry *oe = priv;
> +
> + kfree(oe);
> +}
> +
> +static int tcf_gate_get_entries(struct flow_action_entry *entry,
> + const struct tc_action *act)
> +{
> + entry->gate.entries = tcf_gate_get_list(act);
> +
> + if (!entry->gate.entries)
> + return -EINVAL;
> +
> + entry->destructor = tcf_gate_entry_destructor;
> + entry->destructor_priv = entry->gate.entries;
> +
> + return 0;
> +}
> +
> int tc_setup_flow_action(struct flow_action *flow_action,
> const struct tcf_exts *exts)
> {
> @@ -3672,6 +3694,17 @@ int tc_setup_flow_action(struct flow_action *flow_action,
> } else if (is_tcf_skbedit_priority(act)) {
> entry->id = FLOW_ACTION_PRIORITY;
> entry->priority = tcf_skbedit_priority(act);
> + } else if (is_tcf_gate(act)) {
> + entry->id = FLOW_ACTION_GATE;
> + entry->gate.index = tcf_gate_index(act);
> + entry->gate.prio = tcf_gate_prio(act);
> + entry->gate.basetime = tcf_gate_basetime(act);
> + entry->gate.cycletime = tcf_gate_cycletime(act);
> + entry->gate.cycletimeext = tcf_gate_cycletimeext(act);
> + entry->gate.num_entries = tcf_gate_num_entries(act);
> + err = tcf_gate_get_entries(entry, act);
> + if (err)
> + goto err_out;
> } else {
> err = -EOPNOTSUPP;
> goto err_out_locked;