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SubjectRe: [v3,net-next 1/4] net: qos: introduce a gate control flow action
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On Sat 25 Apr 2020 at 11:56, Po Liu <po.liu@nxp.com> wrote:
> Hi Vlad,
>
>> -----Original Message-----
>> From: Vlad Buslov <vlad@buslov.dev>
>> Sent: 2020年4月23日 19:03
>> To: Po Liu <po.liu@nxp.com>
>> Cc: davem@davemloft.net; linux-kernel@vger.kernel.org;
>> netdev@vger.kernel.org; vinicius.gomes@intel.com; Claudiu Manoil
>> <claudiu.manoil@nxp.com>; Vladimir Oltean <vladimir.oltean@nxp.com>;
>> Alexandru Marginean <alexandru.marginean@nxp.com>;
>> michael.chan@broadcom.com; vishal@chelsio.com;
>> saeedm@mellanox.com; leon@kernel.org; jiri@mellanox.com;
>> idosch@mellanox.com; alexandre.belloni@bootlin.com;
>> UNGLinuxDriver@microchip.com; kuba@kernel.org; jhs@mojatatu.com;
>> xiyou.wangcong@gmail.com; simon.horman@netronome.com;
>> pablo@netfilter.org; moshe@mellanox.com; m-karicheri2@ti.com;
>> andre.guedes@linux.intel.com; stephen@networkplumber.org
>> Subject: Re: [EXT] Re: [v3,net-next 1/4] net: qos: introduce a gate control
>> flow action
>>
>> Caution: EXT Email
>>
>> On Thu 23 Apr 2020 at 11:32, Po Liu <po.liu@nxp.com> wrote:
>> >> -----Original Message-----
>> >> From: Vlad Buslov <vlad@buslov.dev>
>> >> Sent: 2020年4月23日 15:43
>> >> To: Po Liu <po.liu@nxp.com>
>> >> Cc: Vlad Buslov <vlad@buslov.dev>; davem@davemloft.net; linux-
>> >> kernel@vger.kernel.org; netdev@vger.kernel.org;
>> >> vinicius.gomes@intel.com; Claudiu Manoil <claudiu.manoil@nxp.com>;
>> >> Vladimir Oltean <vladimir.oltean@nxp.com>; Alexandru Marginean
>> >> <alexandru.marginean@nxp.com>; michael.chan@broadcom.com;
>> >> vishal@chelsio.com; saeedm@mellanox.com; leon@kernel.org;
>> >> jiri@mellanox.com; idosch@mellanox.com;
>> >> alexandre.belloni@bootlin.com; UNGLinuxDriver@microchip.com;
>> >> kuba@kernel.org; jhs@mojatatu.com; xiyou.wangcong@gmail.com;
>> >> simon.horman@netronome.com; pablo@netfilter.org;
>> moshe@mellanox.com;
>> >> m-karicheri2@ti.com; andre.guedes@linux.intel.com;
>> >> stephen@networkplumber.org
>> >> Subject: Re: [EXT] Re: [v3,net-next 1/4] net: qos: introduce a gate
>> >> control flow action
>> >>
>> >> Caution: EXT Email
>> >>
>> >> On Thu 23 Apr 2020 at 06:14, Po Liu <po.liu@nxp.com> wrote:
>> >> > Hi Vlad Buslov,
>> >> >
>> >> >> -----Original Message-----
>> >> >> From: Vlad Buslov <vlad@buslov.dev>
>> >> >> Sent: 2020年4月22日 21:23
>> >> >> To: Po Liu <po.liu@nxp.com>
>> >> >> Cc: davem@davemloft.net; linux-kernel@vger.kernel.org;
>> >> >> netdev@vger.kernel.org; vinicius.gomes@intel.com; Claudiu Manoil
>> >> >> <claudiu.manoil@nxp.com>; Vladimir Oltean
>> >> <vladimir.oltean@nxp.com>;
>> >> >> Alexandru Marginean <alexandru.marginean@nxp.com>;
>> >> >> michael.chan@broadcom.com; vishal@chelsio.com;
>> >> saeedm@mellanox.com;
>> >> >> leon@kernel.org; jiri@mellanox.com; idosch@mellanox.com;
>> >> >> alexandre.belloni@bootlin.com; UNGLinuxDriver@microchip.com;
>> >> >> kuba@kernel.org; jhs@mojatatu.com; xiyou.wangcong@gmail.com;
>> >> >> simon.horman@netronome.com; pablo@netfilter.org;
>> >> moshe@mellanox.com;
>> >> >> m-karicheri2@ti.com; andre.guedes@linux.intel.com;
>> >> >> stephen@networkplumber.org
>> >> >> Subject: [EXT] Re: [v3,net-next 1/4] net: qos: introduce a gate
>> >> >> control flow action
>> >> >>
>> >> >> Caution: EXT Email
>> >> >>
>> >> >> Hi Po,
>> >> >>
>> >> >> On Wed 22 Apr 2020 at 05:48, Po Liu <Po.Liu@nxp.com> wrote:
>> >> >> > Introduce a ingress frame gate control flow action.
>> >> >> > Tc gate action does the work like this:
>> >> >> > Assume there is a gate allow specified ingress frames can be
>> >> >> > passed at specific time slot, and be dropped at specific time
>> >> >> > slot. Tc filter chooses the ingress frames, and tc gate action
>> >> >> > would specify what slot does these frames can be passed to
>> >> >> > device and what time slot would be dropped.
>> >> >> > Tc gate action would provide an entry list to tell how much time
>> >> >> > gate keep open and how much time gate keep state close. Gate
>> >> action
>> >> >> > also assign a start time to tell when the entry list start. Then
>> >> >> > driver would repeat the gate entry list cyclically.
>> >> >> > For the software simulation, gate action requires the user
>> >> >> > assign a time clock type.
>> >> >> >
>> >> >> > Below is the setting example in user space. Tc filter a stream
>> >> >> > source ip address is 192.168.0.20 and gate action own two time
>> >> >> > slots. One is last 200ms gate open let frame pass another is
>> >> >> > last 100ms gate close let frames dropped. When the frames have
>> >> >> > passed total frames over
>> >> >> > 8000000 bytes, frames will be dropped in one 200000000ns time
>> slot.
>> >> >> >
>> >> >> >> tc qdisc add dev eth0 ingress
>> >> >> >
>> >> >> >> tc filter add dev eth0 parent ffff: protocol ip \
>> >> >> > flower src_ip 192.168.0.20 \
>> >> >> > action gate index 2 clockid CLOCK_TAI \
>> >> >> > sched-entry open 200000000 -1 8000000 \
>> >> >> > sched-entry close 100000000 -1 -1
>> >> >> >
>> >> >> >> tc chain del dev eth0 ingress chain 0
>> >> >> >
>> >> >> > "sched-entry" follow the name taprio style. Gate state is
>> >> >> > "open"/"close". Follow with period nanosecond. Then next item is
>> >> >> > internal priority value means which ingress queue should put. "-1"
>> >> >> > means wildcard. The last value optional specifies the maximum
>> >> >> > number of MSDU octets that are permitted to pass the gate during
>> >> >> > the specified time interval.
>> >> >> > Base-time is not set will be 0 as default, as result start time
>> >> >> > would be ((N + 1) * cycletime) which is the minimal of future time.
>> >> >> >
>> >> >> > Below example shows filtering a stream with destination mac
>> >> >> > address is
>> >> >> > 10:00:80:00:00:00 and ip type is ICMP, follow the action gate.
>> >> >> > The gate action would run with one close time slot which means
>> >> >> > always keep
>> >> >> close.
>> >> >> > The time cycle is total 200000000ns. The base-time would calculate
>> by:
>> >> >> >
>> >> >> > 1357000000000 + (N + 1) * cycletime
>> >> >> >
>> >> >> > When the total value is the future time, it will be the start time.
>> >> >> > The cycletime here would be 200000000ns for this case.
>> >> >> >
>> >> >> >> tc filter add dev eth0 parent ffff: protocol ip \
>> >> >> > flower skip_hw ip_proto icmp dst_mac 10:00:80:00:00:00 \
>> >> >> > action gate index 12 base-time 1357000000000 \
>> >> >> > sched-entry close 200000000 -1 -1 \
>> >> >> > clockid CLOCK_TAI
>> >> >> >
>> >> >> > Signed-off-by: Po Liu <Po.Liu@nxp.com>
>> >> >> > ---
>> >> >> > include/net/tc_act/tc_gate.h | 54 +++
>> >> >> > include/uapi/linux/pkt_cls.h | 1 +
>> >> >> > include/uapi/linux/tc_act/tc_gate.h | 47 ++
>> >> >> > net/sched/Kconfig | 13 +
>> >> >> > net/sched/Makefile | 1 +
>> >> >> > net/sched/act_gate.c | 647
>> >> ++++++++++++++++++++++++++++
>> >> >> > 6 files changed, 763 insertions(+) create mode 100644
>> >> >> > include/net/tc_act/tc_gate.h create mode 100644
>> >> >> > include/uapi/linux/tc_act/tc_gate.h
>> >> >> > create mode 100644 net/sched/act_gate.c
>> >> >> >
>> >> >> > diff --git a/include/net/tc_act/tc_gate.h
>> >> >> > b/include/net/tc_act/tc_gate.h new file mode 100644 index
>> >> >> > 000000000000..b0ace55b2aaa
>> >> >> > --- /dev/null
>> >> >> > +++ b/include/net/tc_act/tc_gate.h
>> >> >> > @@ -0,0 +1,54 @@
>> >> >> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
>> >> >> > +/* Copyright 2020 NXP */
>> >> >> > +
>> >> >> > +#ifndef __NET_TC_GATE_H
>> >> >> > +#define __NET_TC_GATE_H
>> >> >> > +
>> >> >> > +#include <net/act_api.h>
>> >> >> > +#include <linux/tc_act/tc_gate.h>
>> >> >> > +
>> >> >> > +struct tcfg_gate_entry {
>> >> >> > + int index;
>> >> >> > + u8 gate_state;
>> >> >> > + u32 interval;
>> >> >> > + s32 ipv;
>> >> >> > + s32 maxoctets;
>> >> >> > + struct list_head list;
>> >> >> > +};
>> >> >> > +
>> >> >> > +struct tcf_gate_params {
>> >> >> > + s32 tcfg_priority;
>> >> >> > + u64 tcfg_basetime;
>> >> >> > + u64 tcfg_cycletime;
>> >> >> > + u64 tcfg_cycletime_ext;
>> >> >> > + u32 tcfg_flags;
>> >> >> > + s32 tcfg_clockid;
>> >> >> > + size_t num_entries;
>> >> >> > + struct list_head entries;
>> >> >> > +};
>> >> >> > +
>> >> >> > +#define GATE_ACT_GATE_OPEN BIT(0)
>> >> >> > +#define GATE_ACT_PENDING BIT(1)
>> >> >> > +struct gate_action {
>> >> >> > + struct tcf_gate_params param;
>> >> >> > + spinlock_t entry_lock;
>> >> >> > + u8 current_gate_status;
>> >> >> > + ktime_t current_close_time;
>> >> >> > + u32 current_entry_octets;
>> >> >> > + s32 current_max_octets;
>> >> >> > + struct tcfg_gate_entry __rcu *next_entry;
>> >> >> > + struct hrtimer hitimer;
>> >> >> > + enum tk_offsets tk_offset;
>> >> >> > + struct rcu_head rcu;
>> >> >> > +};
>> >> >> > +
>> >> >> > +struct tcf_gate {
>> >> >> > + struct tc_action common;
>> >> >> > + struct gate_action __rcu *actg;
>> >> >> > +};
>> >> >> > +#define to_gate(a) ((struct tcf_gate *)a)
>> >> >> > +
>> >> >> > +#define get_gate_param(act) ((struct tcf_gate_params *)act)
>> >> >> > +#define
>> >> >> > +get_gate_action(p) ((struct gate_action *)p)
>> >> >> > +
>> >> >> > +#endif
>> >> >> > diff --git a/include/uapi/linux/pkt_cls.h
>> >> >> > b/include/uapi/linux/pkt_cls.h index 9f06d29cab70..fc672b232437
>> >> >> 100644
>> >> >> > --- a/include/uapi/linux/pkt_cls.h
>> >> >> > +++ b/include/uapi/linux/pkt_cls.h
>> >> >> > @@ -134,6 +134,7 @@ enum tca_id {
>> >> >> > TCA_ID_CTINFO,
>> >> >> > TCA_ID_MPLS,
>> >> >> > TCA_ID_CT,
>> >> >> > + TCA_ID_GATE,
>> >> >> > /* other actions go here */
>> >> >> > __TCA_ID_MAX = 255
>> >> >> > };
>> >> >> > diff --git a/include/uapi/linux/tc_act/tc_gate.h
>> >> >> > b/include/uapi/linux/tc_act/tc_gate.h
>> >> >> > new file mode 100644
>> >> >> > index 000000000000..f214b3a6d44f
>> >> >> > --- /dev/null
>> >> >> > +++ b/include/uapi/linux/tc_act/tc_gate.h
>> >> >> > @@ -0,0 +1,47 @@
>> >> >> > +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
>> >> >> > +/* Copyright 2020 NXP */
>> >> >> > +
>> >> >> > +#ifndef __LINUX_TC_GATE_H
>> >> >> > +#define __LINUX_TC_GATE_H
>> >> >> > +
>> >> >> > +#include <linux/pkt_cls.h>
>> >> >> > +
>> >> >> > +struct tc_gate {
>> >> >> > + tc_gen;
>> >> >> > +};
>> >> >> > +
>> >> >> > +enum {
>> >> >> > + TCA_GATE_ENTRY_UNSPEC,
>> >> >> > + TCA_GATE_ENTRY_INDEX,
>> >> >> > + TCA_GATE_ENTRY_GATE,
>> >> >> > + TCA_GATE_ENTRY_INTERVAL,
>> >> >> > + TCA_GATE_ENTRY_IPV,
>> >> >> > + TCA_GATE_ENTRY_MAX_OCTETS,
>> >> >> > + __TCA_GATE_ENTRY_MAX,
>> >> >> > +};
>> >> >> > +#define TCA_GATE_ENTRY_MAX (__TCA_GATE_ENTRY_MAX - 1)
>> >> >> > +
>> >> >> > +enum {
>> >> >> > + TCA_GATE_ONE_ENTRY_UNSPEC,
>> >> >> > + TCA_GATE_ONE_ENTRY,
>> >> >> > + __TCA_GATE_ONE_ENTRY_MAX,
>> >> >> > +};
>> >> >> > +#define TCA_GATE_ONE_ENTRY_MAX
>> >> (__TCA_GATE_ONE_ENTRY_MAX
>> >> >> - 1)
>> >> >> > +
>> >> >> > +enum {
>> >> >> > + TCA_GATE_UNSPEC,
>> >> >> > + TCA_GATE_TM,
>> >> >> > + TCA_GATE_PARMS,
>> >> >> > + TCA_GATE_PAD,
>> >> >> > + TCA_GATE_PRIORITY,
>> >> >> > + TCA_GATE_ENTRY_LIST,
>> >> >> > + TCA_GATE_BASE_TIME,
>> >> >> > + TCA_GATE_CYCLE_TIME,
>> >> >> > + TCA_GATE_CYCLE_TIME_EXT,
>> >> >> > + TCA_GATE_FLAGS,
>> >> >> > + TCA_GATE_CLOCKID,
>> >> >> > + __TCA_GATE_MAX,
>> >> >> > +};
>> >> >> > +#define TCA_GATE_MAX (__TCA_GATE_MAX - 1)
>> >> >> > +
>> >> >> > +#endif
>> >> >> > diff --git a/net/sched/Kconfig b/net/sched/Kconfig index
>> >> >> > bfbefb7bff9d..1314549c7567 100644
>> >> >> > --- a/net/sched/Kconfig
>> >> >> > +++ b/net/sched/Kconfig
>> >> >> > @@ -981,6 +981,19 @@ config NET_ACT_CT
>> >> >> > To compile this code as a module, choose M here: the
>> >> >> > module will be called act_ct.
>> >> >> >
>> >> >> > +config NET_ACT_GATE
>> >> >> > + tristate "Frame gate entry list control tc action"
>> >> >> > + depends on NET_CLS_ACT
>> >> >> > + help
>> >> >> > + Say Y here to allow to control the ingress flow to be passed
>> at
>> >> >> > + specific time slot and be dropped at other specific time slot
>> by
>> >> >> > + the gate entry list. The manipulation will simulate the IEEE
>> >> >> > + 802.1Qci stream gate control behavior.
>> >> >> > +
>> >> >> > + If unsure, say N.
>> >> >> > + To compile this code as a module, choose M here: the
>> >> >> > + module will be called act_gate.
>> >> >> > +
>> >> >> > config NET_IFE_SKBMARK
>> >> >> > tristate "Support to encoding decoding skb mark on IFE action"
>> >> >> > depends on NET_ACT_IFE
>> >> >> > diff --git a/net/sched/Makefile b/net/sched/Makefile index
>> >> >> > 31c367a6cd09..66bbf9a98f9e 100644
>> >> >> > --- a/net/sched/Makefile
>> >> >> > +++ b/net/sched/Makefile
>> >> >> > @@ -30,6 +30,7 @@ obj-$(CONFIG_NET_IFE_SKBPRIO) +=
>> >> >> act_meta_skbprio.o
>> >> >> > obj-$(CONFIG_NET_IFE_SKBTCINDEX) += act_meta_skbtcindex.o
>> >> >> > obj-$(CONFIG_NET_ACT_TUNNEL_KEY)+= act_tunnel_key.o
>> >> >> > obj-$(CONFIG_NET_ACT_CT) += act_ct.o
>> >> >> > +obj-$(CONFIG_NET_ACT_GATE) += act_gate.o
>> >> >> > obj-$(CONFIG_NET_SCH_FIFO) += sch_fifo.o
>> >> >> > obj-$(CONFIG_NET_SCH_CBQ) += sch_cbq.o
>> >> >> > obj-$(CONFIG_NET_SCH_HTB) += sch_htb.o
>> >> >> > diff --git a/net/sched/act_gate.c b/net/sched/act_gate.c new
>> >> >> > file mode
>> >> >> > 100644 index 000000000000..e932f402b4f1
>> >> >> > --- /dev/null
>> >> >> > +++ b/net/sched/act_gate.c
>> >> >> > @@ -0,0 +1,647 @@
>> >> >> > +// SPDX-License-Identifier: GPL-2.0-or-later
>> >> >> > +/* Copyright 2020 NXP */
>> >> >> > +
>> >> >> > +#include <linux/module.h>
>> >> >> > +#include <linux/types.h>
>> >> >> > +#include <linux/kernel.h>
>> >> >> > +#include <linux/string.h>
>> >> >> > +#include <linux/errno.h>
>> >> >> > +#include <linux/skbuff.h>
>> >> >> > +#include <linux/rtnetlink.h>
>> >> >> > +#include <linux/init.h>
>> >> >> > +#include <linux/slab.h>
>> >> >> > +#include <net/act_api.h>
>> >> >> > +#include <net/netlink.h>
>> >> >> > +#include <net/pkt_cls.h>
>> >> >> > +#include <net/tc_act/tc_gate.h>
>> >> >> > +
>> >> >> > +static unsigned int gate_net_id; static struct tc_action_ops
>> >> >> > +act_gate_ops;
>> >> >> > +
>> >> >> > +static ktime_t gate_get_time(struct gate_action *gact) {
>> >> >> > + ktime_t mono = ktime_get();
>> >> >> > +
>> >> >> > + switch (gact->tk_offset) {
>> >> >> > + case TK_OFFS_MAX:
>> >> >> > + return mono;
>> >> >> > + default:
>> >> >> > + return ktime_mono_to_any(mono, gact->tk_offset);
>> >> >> > + }
>> >> >> > +
>> >> >> > + return KTIME_MAX;
>> >> >> > +}
>> >> >> > +
>> >> >> > +static int gate_get_start_time(struct gate_action *gact,
>> >> >> > +ktime_t
>> >> >> > +*start) {
>> >> >> > + struct tcf_gate_params *param = get_gate_param(gact);
>> >> >> > + ktime_t now, base, cycle;
>> >> >> > + u64 n;
>> >> >> > +
>> >> >> > + base = ns_to_ktime(param->tcfg_basetime);
>> >> >> > + now = gate_get_time(gact);
>> >> >> > +
>> >> >> > + if (ktime_after(base, now)) {
>> >> >> > + *start = base;
>> >> >> > + return 0;
>> >> >> > + }
>> >> >> > +
>> >> >> > + cycle = param->tcfg_cycletime;
>> >> >> > +
>> >> >> > + /* cycle time should not be zero */
>> >> >> > + if (WARN_ON(!cycle))
>> >> >> > + return -EFAULT;
>> >> >>
>> >> >> Looking at the init code it seems that this value can be set to 0
>> >> >> directly from netlink packet without further validation, which
>> >> >> would allow user to trigger warning here.
>> >> >
>> >> > Yes, will avoid at ahead point.
>> >> >
>> >> >>
>> >> >> > +
>> >> >> > + n = div64_u64(ktime_sub_ns(now, base), cycle);
>> >> >> > + *start = ktime_add_ns(base, (n + 1) * cycle);
>> >> >> > + return 0;
>> >> >> > +}
>> >> >> > +
>> >> >> > +static void gate_start_timer(struct gate_action *gact, ktime_t
>> >> >> > +start) {
>> >> >> > + ktime_t expires;
>> >> >> > +
>> >> >> > + expires = hrtimer_get_expires(&gact->hitimer);
>> >> >> > + if (expires == 0)
>> >> >> > + expires = KTIME_MAX;
>> >> >> > +
>> >> >> > + start = min_t(ktime_t, start, expires);
>> >> >> > +
>> >> >> > + hrtimer_start(&gact->hitimer, start, HRTIMER_MODE_ABS); }
>> >> >> > +
>> >> >> > +static enum hrtimer_restart gate_timer_func(struct hrtimer
>> *timer) {
>> >> >> > + struct gate_action *gact = container_of(timer, struct
>> gate_action,
>> >> >> > + hitimer);
>> >> >> > + struct tcf_gate_params *p = get_gate_param(gact);
>> >> >> > + struct tcfg_gate_entry *next;
>> >> >> > + ktime_t close_time, now;
>> >> >> > +
>> >> >> > + spin_lock(&gact->entry_lock);
>> >> >> > +
>> >> >> > + next = rcu_dereference_protected(gact->next_entry,
>> >> >> > +
>> >> >> > + lockdep_is_held(&gact->entry_lock));
>> >> >> > +
>> >> >> > + /* cycle start, clear pending bit, clear total octets */
>> >> >> > + gact->current_gate_status = next->gate_state ?
>> >> >> GATE_ACT_GATE_OPEN : 0;
>> >> >> > + gact->current_entry_octets = 0;
>> >> >> > + gact->current_max_octets = next->maxoctets;
>> >> >> > +
>> >> >> > + gact->current_close_time = ktime_add_ns(gact-
>> >> >current_close_time,
>> >> >> > + next->interval);
>> >> >> > +
>> >> >> > + close_time = gact->current_close_time;
>> >> >> > +
>> >> >> > + if (list_is_last(&next->list, &p->entries))
>> >> >> > + next = list_first_entry(&p->entries,
>> >> >> > + struct tcfg_gate_entry, list);
>> >> >> > + else
>> >> >> > + next = list_next_entry(next, list);
>> >> >> > +
>> >> >> > + now = gate_get_time(gact);
>> >> >> > +
>> >> >> > + if (ktime_after(now, close_time)) {
>> >> >> > + ktime_t cycle, base;
>> >> >> > + u64 n;
>> >> >> > +
>> >> >> > + cycle = p->tcfg_cycletime;
>> >> >> > + base = ns_to_ktime(p->tcfg_basetime);
>> >> >> > + n = div64_u64(ktime_sub_ns(now, base), cycle);
>> >> >> > + close_time = ktime_add_ns(base, (n + 1) * cycle);
>> >> >> > + }
>> >> >> > +
>> >> >> > + rcu_assign_pointer(gact->next_entry, next);
>> >> >> > + spin_unlock(&gact->entry_lock);
>> >> >>
>> >> >> I have couple of question about synchronization here:
>> >> >>
>> >> >> - Why do you need next_entry to be rcu pointer? It is only
>> >> >> assigned here with entry_lock protection and in init code before
>> >> >> action is visible to concurrent users. I don't see any unlocked
>> >> >> rcu-protected readers here that could benefit from it.
>> >> >>
>> >> >> - Why create dedicated entry_lock instead of using already
>> >> >> existing
>> >> >> per- action tcf_lock?
>> >> >
>> >> > Will try to use the tcf_lock for verification.
>> >> > The thoughts came from that the timer period arrived then check
>> >> > through the list and then update next time would take much more
>> time.
>> >> > Action function would be busy when traffic. So use a separate lock
>> >> > here for
>> >> >
>> >> >>
>> >> >> > +
>> >> >> > + hrtimer_set_expires(&gact->hitimer, close_time);
>> >> >> > +
>> >> >> > + return HRTIMER_RESTART;
>> >> >> > +}
>> >> >> > +
>> >> >> > +static int tcf_gate_act(struct sk_buff *skb, const struct tc_action
>> *a,
>> >> >> > + struct tcf_result *res) {
>> >> >> > + struct tcf_gate *g = to_gate(a);
>> >> >> > + struct gate_action *gact;
>> >> >> > + int action;
>> >> >> > +
>> >> >> > + tcf_lastuse_update(&g->tcf_tm);
>> >> >> > + bstats_cpu_update(this_cpu_ptr(g->common.cpu_bstats),
>> >> >> > + skb);
>> >> >> > +
>> >> >> > + action = READ_ONCE(g->tcf_action);
>> >> >> > + rcu_read_lock();
>> >> >>
>> >> >> Action fastpath is already rcu read lock protected, you don't need
>> >> >> to manually obtain it.
>> >> >
>> >> > Will be removed.
>> >> >
>> >> >>
>> >> >> > + gact = rcu_dereference_bh(g->actg);
>> >> >> > + if (unlikely(gact->current_gate_status &
>> >> >> > + GATE_ACT_PENDING)) {
>> >> >>
>> >> >> Can't current_gate_status be concurrently modified by timer
>> callback?
>> >> >> This function doesn't use entry_lock to synchronize with timer.
>> >> >
>> >> > Will try tcf_lock either.
>> >> >
>> >> >>
>> >> >> > + rcu_read_unlock();
>> >> >> > + return action;
>> >> >> > + }
>> >> >> > +
>> >> >> > + if (!(gact->current_gate_status & GATE_ACT_GATE_OPEN))
>> >> >>
>> >> >> ...and here
>> >> >>
>> >> >> > + goto drop;
>> >> >> > +
>> >> >> > + if (gact->current_max_octets >= 0) {
>> >> >> > + gact->current_entry_octets += qdisc_pkt_len(skb);
>> >> >> > + if (gact->current_entry_octets >
>> >> >> > + gact->current_max_octets) {
>> >> >>
>> >> >> here also.
>> >> >>
>> >> >> > +
>> >> >> > + qstats_overlimit_inc(this_cpu_ptr(g->common.cpu_qstats));
>> >> >>
>> >> >> Please use tcf_action_inc_overlimit_qstats() and other wrappers
>> >> >> for
>> >> stats.
>> >> >> Otherwise it will crash if user passes
>> >> TCA_ACT_FLAGS_NO_PERCPU_STATS
>> >> >> flag.
>> >> >
>> >> > The tcf_action_inc_overlimit_qstats() can't show limit counts in tc
>> >> > show
>> >> command. Is there anything need to do?
>> >>
>> >> What do you mean? Internally tcf_action_inc_overlimit_qstats() just
>> >> calls qstats_overlimit_inc, if cpu_qstats percpu counter is not NULL:
>> >>
>> >>
>> >> if (likely(a->cpu_qstats)) {
>> >> qstats_overlimit_inc(this_cpu_ptr(a->cpu_qstats));
>> >> return;
>> >> }
>> >>
>> >> Is there a subtle bug somewhere in this function?
>> >
>> > Sorry, I updated using the tcf_action_*, and the counting is ok. I moved
>> back to the qstats_overlimit_inc() because tcf_action_* () include the
>> spin_lock(&a->tcfa_lock).
>> > I would update to tcf_action_* () increate.
>>
>> BTW if you end up with synchronizing fastpath with tcfa_lock, then you
>> don't need to use tcf_action_*stats() helpers and percpu counters (they
>> will only slow down action init and increase memory usage without
>> providing any improvements for parallelism). Instead, you can just directly
>> change the tcf_{q|b}stats while holding the tcfa_lock. Check pedit for
>> example of such action.
>
> I tried fix two versions as your suggestion. One is keep gate_action structure as pointer and also keep the entry_lock to fix the rcu free related issue. Another way to remove the struct gate_action and move them to struct tcf_gate align with struct tc_action. I would choose second one for next version uploading since it would not use rcu which more simple(refer the pedit action). I met the status update selection like here your mention. Since I use spin_lock(&a->tcfa_lock), but I can't using code like:
> p->tcf_qstats.overlimits++;
> This won't show by "tc filter show" since it is showing overlimits and drop from "qstats_overlimit_inc(this_cpu_ptr(a->cpu_qstats));"
> So I choose the "tcf_action_inc_overlimit_qstats()" and excluded in the spin_lock.

I guess you didn't update the init function to skip percpu counters
allocation which causes zero values from percpu stats to be sent to
userland even when you increment regular stats. Check the following line
from pedit init:

ret = tcf_idr_create(tn, index, est, a,
&act_pedit_ops, bind, false, 0);

Here flags value is hardcoded to zero and cpustats is false so regular
counters can be directly used.

>
>>
>> >
>> >>
>> >> >
>> >> > Br,
>> >> > Po Liu
>> >
>> > Thanks a lot.
>> >
>> > Br,
>> > Po Liu
>
> Thanks a lot.
> Br,
> Po Liu

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