[PATCH net-next 1/2] net sched actions: dump more than TCA_ACT_MAX_PRIO actions per batch

[PATCH net-next 1/2] net sched actions: dump more than TCA_ACT_MAX_PRIO actions per batch

[Jamal Hadi Salim]

From: Jamal Hadi Salim <jhs@mojatatu.com>

When you dump hundreds of thousands of actions, getting only 32 per
dump batch even when the socket buffer and memory allocations allow
is inefficient.

With this change, the user will get as many as possibly fitting
within the given constraints available to the kernel.

A new top level TLV space is introduced. An attribute
TCAA_ACT_FLAGS is used to carry the flags indicating the user
is capable of processing these large dumps. Older user space which
doesnt set this flag doesnt get the large (than 32) batches.
The kernel uses the TCAA_ACT_COUNT attribute to tell the user how many
actions are put in a single batch. As such user space app knows how long
to iterate (independent of the type of action being dumped)
instead of hardcoded maximum of 32.

Some results dumping 1.5M actions, first unpatched tc which the
kernel doesnt help:

prompt$ time -p tc actions ls action gact | grep index | wc -l
1500000
real 1388.43
user 2.07
sys 1386.79

Now lets see a patched tc which sets the correct flags when requesting
a dump:

prompt$ time -p updatedtc actions ls action gact | grep index | wc -l
1500000
real 178.13
user 2.02
sys 176.96

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
 MAINTAINERS                    |  1 +
 include/uapi/linux/rtnetlink.h | 21 +++++++++++++++++++--
 net/sched/act_api.c            | 43 ++++++++++++++++++++++++++++++++----------
 3 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 7b4b828..94eadbc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12198,6 +12198,7 @@ F:	kernel/taskstats.c
 
 TC subsystem
 M:	Jamal Hadi Salim <jhs@mojatatu.com>
+M:	Jamal Hadi Salim <jhs@mojatatu.com>
 L:	netdev@vger.kernel.org
 S:	Maintained
 F:	include/net/pkt_cls.h
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index cce0613..c7080ec 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -674,10 +674,27 @@ struct tcamsg {
 	unsigned char	tca__pad1;
 	unsigned short	tca__pad2;
 };
+
+enum {
+	TCAA_UNSPEC,
+	TCAA_ACT_TAB,
+	TCAA_ACT_FLAGS,
+	TCAA_ACT_COUNT,
+	__TCAA_MAX
+};
+
+#define TCAA_MAX (__TCAA_MAX - 1)
 #define TA_RTA(r)  ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct tcamsg))))
 #define TA_PAYLOAD(n) NLMSG_PAYLOAD(n,sizeof(struct tcamsg))
-#define TCA_ACT_TAB 1 /* attr type must be >=1 */	
-#define TCAA_MAX 1
+#define TCA_ACT_TAB TCAA_ACT_TAB
+/* tcamsg flags stored in attribute TCAA_ACT_FLAGS
+ *
+ * ACT_LARGE_DUMP_ON user->kernel to request for larger than TCA_ACT_MAX_PRIO
+ * actions in a dump. All dump responses will contain the number of actions
+ * being dumped stored in for user app's consumption in TCAA_ACT_COUNT
+ *
+ */
+#define ACT_LARGE_DUMP_ON		(1 << 0)
 
 /* New extended info filters for IFLA_EXT_MASK */
 #define RTEXT_FILTER_VF		(1 << 0)
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 82b1d48..45e1cf7 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -83,6 +83,7 @@ static int tcf_dump_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
 			   struct netlink_callback *cb)
 {
 	int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
+	unsigned short act_flags = cb->args[2];
 	struct nlattr *nest;
 
 	spin_lock_bh(&hinfo->lock);
@@ -111,14 +112,18 @@ static int tcf_dump_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
 			}
 			nla_nest_end(skb, nest);
 			n_i++;
-			if (n_i >= TCA_ACT_MAX_PRIO)
+			if (!(act_flags & ACT_LARGE_DUMP_ON) &&
+			    n_i >= TCA_ACT_MAX_PRIO)
 				goto done;
 		}
 	}
 done:
 	spin_unlock_bh(&hinfo->lock);
-	if (n_i)
+	if (n_i) {
 		cb->args[0] += n_i;
+		if (act_flags & ACT_LARGE_DUMP_ON)
+			cb->args[1] = n_i;
+	}
 	return n_i;
 
 nla_put_failure:
@@ -993,11 +998,15 @@ static int tcf_action_add(struct net *net, struct nlattr *nla,
 	return tcf_add_notify(net, n, &actions, portid);
 }
 
+static const struct nla_policy tcaa_policy[TCAA_MAX + 1] = {
+	[TCAA_ACT_FLAGS]      = { .type = NLA_U32 },
+};
+
 static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
 			 struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
-	struct nlattr *tca[TCA_ACT_MAX + 1];
+	struct nlattr *tca[TCAA_MAX + 1];
 	u32 portid = skb ? NETLINK_CB(skb).portid : 0;
 	int ret = 0, ovr = 0;
 
@@ -1005,7 +1014,7 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
 	    !netlink_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
-	ret = nlmsg_parse(n, sizeof(struct tcamsg), tca, TCA_ACT_MAX, NULL,
+	ret = nlmsg_parse(n, sizeof(struct tcamsg), tca, TCAA_MAX, tcaa_policy,
 			  extack);
 	if (ret < 0)
 		return ret;
@@ -1046,16 +1055,12 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
 	return ret;
 }
 
-static struct nlattr *find_dump_kind(const struct nlmsghdr *n)
+static struct nlattr *find_dump_kind(struct nlattr **nla)
 {
 	struct nlattr *tb1, *tb2[TCA_ACT_MAX + 1];
 	struct nlattr *tb[TCA_ACT_MAX_PRIO + 1];
-	struct nlattr *nla[TCAA_MAX + 1];
 	struct nlattr *kind;
 
-	if (nlmsg_parse(n, sizeof(struct tcamsg), nla, TCAA_MAX,
-			NULL, NULL) < 0)
-		return NULL;
 	tb1 = nla[TCA_ACT_TAB];
 	if (tb1 == NULL)
 		return NULL;
@@ -1081,9 +1086,18 @@ static int tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
 	struct nlattr *nest;
 	struct tc_action_ops *a_o;
 	int ret = 0;
+	struct nlattr *tcaa[TCAA_MAX + 1];
 	struct tcamsg *t = (struct tcamsg *) nlmsg_data(cb->nlh);
-	struct nlattr *kind = find_dump_kind(cb->nlh);
+	struct nlattr *kind = NULL;
+	u32 act_flags = 0;
+
+	ret = nlmsg_parse(cb->nlh, sizeof(struct tcamsg), tcaa, TCAA_MAX,
+			  tcaa_policy, NULL);
+	if (ret < 0)
+		return ret;
+
 
+	kind = find_dump_kind(tcaa);
 	if (kind == NULL) {
 		pr_info("tc_dump_action: action bad kind\n");
 		return 0;
@@ -1093,10 +1107,16 @@ static int tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
 	if (a_o == NULL)
 		return 0;
 
+	if (tcaa[TCAA_ACT_FLAGS])
+		act_flags = nla_get_u32(tcaa[TCAA_ACT_FLAGS]);
+
 	nlh = nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 			cb->nlh->nlmsg_type, sizeof(*t), 0);
 	if (!nlh)
 		goto out_module_put;
+
+	cb->args[2] = act_flags;
+
 	t = nlmsg_data(nlh);
 	t->tca_family = AF_UNSPEC;
 	t->tca__pad1 = 0;
@@ -1113,6 +1133,9 @@ static int tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
 	if (ret > 0) {
 		nla_nest_end(skb, nest);
 		ret = skb->len;
+		if (nla_put_u32(skb, TCAA_ACT_COUNT, cb->args[1]))
+			goto out_module_put;
+		cb->args[1] = 0;
 	} else
 		nlmsg_trim(skb, b);
 
-- 
1.9.1

[PATCH net-next 2/2] net sched actions: add time filter for action dumping

[Jamal Hadi Salim]

From: Jamal Hadi Salim <jhs@mojatatu.com>

This adds support for filtering based on time since last used.
When we are dumping a large number of actions it is useful to
have the option of filtering based on when the action was last
used to reduce the amount of data crossing to user space.

With this patch the user space app sets the TCAA_ACT_TIME_FILTER
attribute with the value in milliseconds with "time of interest
since now".  The kernel converts this to jiffies and does the
filtering comparison matching entries that have seen activity
since then and returns them to user space.
Old kernels and old tc continue to work in legacy mode since
they dont specify this attribute.

Some example (we have 400 actions bound to 400 filters); at installation
time using  hacked tc which sets the time of interest to 120 seconds:

prompt$ hackedtc actions ls action gact | grep index | wc -l
400

go get some coffee and  wait for > 120 seconds and try again:

prompt$ hackedtc actions ls action gact | grep index | wc -l
0

Lets see a filter bound to one of these actions:
..
filter pref 10 u32
filter pref 10 u32 fh 800: ht divisor 1
filter pref 10 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:10  (rule hit 2 success 1)
  match 7f000002/ffffffff at 12 (success 1 )
    action order 1: gact action pass
     random type none pass val 0
     index 23 ref 2 bind 1 installed 1145 sec used 802 sec
    Action statistics:
    Sent 84 bytes 1 pkt (dropped 0, overlimits 0 requeues 0)
    backlog 0b 0p requeues 0
....

that coffee took long, no?

Now lets ping -c 1 127.0.0.2, then run the actions again:

prompt$ hackedtc actions ls action gact | grep index | wc -l
1

More details please:

prompt$ hackedtc -s actions ls action gact
total acts 1 flags 0x3

    action order 0: gact action pass
     random type none pass val 0
     index 23 ref 2 bind 1 installed 1270 sec used 30 sec
    Action statistics:
    Sent 168 bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
    backlog 0b 0p requeues 0

And the filter?

filter pref 10 u32
filter pref 10 u32 fh 800: ht divisor 1
filter pref 10 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:10  (rule hit 4 success 2)
  match 7f000002/ffffffff at 12 (success 2 )
    action order 1: gact action pass
     random type none pass val 0
     index 23 ref 2 bind 1 installed 1324 sec used 84 sec
    Action statistics:
    Sent 168 bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
    backlog 0b 0p requeues 0

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
 include/uapi/linux/rtnetlink.h |  1 +
 net/sched/act_api.c            | 23 +++++++++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index c7080ec..1b36cc0 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -680,6 +680,7 @@ enum {
 	TCAA_ACT_TAB,
 	TCAA_ACT_FLAGS,
 	TCAA_ACT_COUNT,
+	TCAA_ACT_TIME_FILTER,
 	__TCAA_MAX
 };
 
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 45e1cf7..cb5b23d 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -84,11 +84,12 @@ static int tcf_dump_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
 {
 	int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
 	unsigned short act_flags = cb->args[2];
+	unsigned long jiffy_filter = cb->args[3];
 	struct nlattr *nest;
 
 	spin_lock_bh(&hinfo->lock);
 
-	s_i = cb->args[0];
+	s_i = cb->args[4];
 
 	for (i = 0; i < (hinfo->hmask + 1); i++) {
 		struct hlist_head *head;
@@ -101,6 +102,11 @@ static int tcf_dump_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
 			if (index < s_i)
 				continue;
 
+			if (jiffy_filter &&
+			    time_after(jiffy_filter,
+				       (unsigned long)p->tcfa_tm.lastuse))
+				continue;
+
 			nest = nla_nest_start(skb, n_i);
 			if (nest == NULL)
 				goto nla_put_failure;
@@ -118,6 +124,9 @@ static int tcf_dump_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
 		}
 	}
 done:
+	if (index > 0)
+		cb->args[4] = index + 1;
+
 	spin_unlock_bh(&hinfo->lock);
 	if (n_i) {
 		cb->args[0] += n_i;
@@ -1090,13 +1099,14 @@ static int tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
 	struct tcamsg *t = (struct tcamsg *) nlmsg_data(cb->nlh);
 	struct nlattr *kind = NULL;
 	u32 act_flags = 0;
+	u32 msecs_filter = 0;
+	unsigned long jiffy_wanted = 0;
 
 	ret = nlmsg_parse(cb->nlh, sizeof(struct tcamsg), tcaa, TCAA_MAX,
 			  tcaa_policy, NULL);
 	if (ret < 0)
 		return ret;
 
-
 	kind = find_dump_kind(tcaa);
 	if (kind == NULL) {
 		pr_info("tc_dump_action: action bad kind\n");
@@ -1110,12 +1120,21 @@ static int tc_dump_action(struct sk_buff *skb, struct netlink_callback *cb)
 	if (tcaa[TCAA_ACT_FLAGS])
 		act_flags = nla_get_u32(tcaa[TCAA_ACT_FLAGS]);
 
+	if (tcaa[TCAA_ACT_TIME_FILTER])
+		msecs_filter = nla_get_u32(tcaa[TCAA_ACT_TIME_FILTER]);
+
 	nlh = nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 			cb->nlh->nlmsg_type, sizeof(*t), 0);
 	if (!nlh)
 		goto out_module_put;
 
+	if (msecs_filter) {
+		unsigned long jiffy_msecs = msecs_to_jiffies(msecs_filter);
+		jiffy_wanted = jiffies - jiffy_msecs;
+	}
+
 	cb->args[2] = act_flags;
+	cb->args[3] = jiffy_wanted;
 
 	t = nlmsg_data(nlh);
 	t->tca_family = AF_UNSPEC;
-- 
1.9.1

Re: [PATCH net-next 1/2] net sched actions: dump more than TCA_ACT_MAX_PRIO actions per batch

[Jamal Hadi Salim]

Please ignore - I will resend. This is corrupt.
Sorry - I will label the next one as v2 even though it is v3.

cheers,
jamal

On 17-04-18 09:08 PM, Jamal Hadi Salim wrote:
> From: Jamal Hadi Salim <jhs@mojatatu.com>
>
> When you dump hundreds of thousands of actions, getting only 32 per
> dump batch even when the socket buffer and memory allocations allow
> is inefficient.
>
> With this change, the user will get as many as possibly fitting