tc: Look for blocks in qevents

When a list of filters at a given block is requested, tc first validates
that the block exists before doing the filter query. Currently the
validation routine checks ingress and egress blocks. But now that blocks
can be bound to qevents as well, qevent blocks should be looked for as
well.

In order to support that, extend struct qdisc_util with a new callback,
has_block. That should report whether, give the attributes in TCA_OPTIONS,
a blocks with a given number is bound to a qevent. In
tc_qdisc_block_exists_cb(), invoke that callback when set.

Add a helper to the tc_qevent module that walks the list of qevents and
looks for a given block. This is meant to be used by the individual qdiscs.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David Ahern <dsahern@kernel.org>

tc/tc_qdisc.c

@@ -478,6 +478,9 @@ static int tc_qdisc_block_exists_cb(struct nlmsghdr *n, void *arg)
 	struct tcmsg *t = NLMSG_DATA(n);
 	struct rtattr *tb[TCA_MAX+1];
 	int len = n->nlmsg_len;
+	struct qdisc_util *q;
+	const char *kind;
+	int err;
 
 	if (n->nlmsg_type != RTM_NEWQDISC)
 		return 0;
@@ -506,6 +509,21 @@ static int tc_qdisc_block_exists_cb(struct nlmsghdr *n, void *arg)
 		if (block == ctx->block_index)
 			ctx->found = true;
 	}
+
+	kind = rta_getattr_str(tb[TCA_KIND]);
+	q = get_qdisc_kind(kind);
+	if (!q)
+		return -1;
+	if (q->has_block) {
+		bool found = false;
+
+		err = q->has_block(q, tb[TCA_OPTIONS], ctx->block_index, &found);
+		if (err)
+			return err;
+		if (found)
+			ctx->found = true;
+	}
+
 	return 0;
 }
 

tc/tc_qevent.c

@@ -92,6 +92,21 @@ void qevents_print(struct qevent_util *qevents, FILE *f)
 		close_json_array(PRINT_ANY, "");
 }
 
+bool qevents_have_block(struct qevent_util *qevents, __u32 block_idx)
+{
+	if (!qevents)
+		return false;
+
+	for (; qevents->id; qevents++) {
+		struct qevent_base *qeb = qevents->data;
+
+		if (qeb->block_idx == block_idx)
+			return true;
+	}
+
+	return false;
+}
+
 int qevents_dump(struct qevent_util *qevents, struct nlmsghdr *n)
 {
 	int err;

tc/tc_qevent.h

@@ -2,6 +2,7 @@
 #ifndef _TC_QEVENT_H_
 #define _TC_QEVENT_H_
 
+#include <stdbool.h>
 #include <linux/types.h>
 #include <libnetlink.h>
 
@@ -37,6 +38,7 @@ int qevent_parse(struct qevent_util *qevents, int *p_argc, char ***p_argv);
 int qevents_read(struct qevent_util *qevents, struct rtattr **tb);
 int qevents_dump(struct qevent_util *qevents, struct nlmsghdr *n);
 void qevents_print(struct qevent_util *qevents, FILE *f);
+bool qevents_have_block(struct qevent_util *qevents, __u32 block_idx);
 
 struct qevent_plain {
 	struct qevent_base base;

tc/tc_util.h

@@ -5,6 +5,7 @@
 #define MAX_MSG 16384
 #include <limits.h>
 #include <linux/if.h>
+#include <stdbool.h>
 
 #include <linux/pkt_sched.h>
 #include <linux/pkt_cls.h>
@@ -40,6 +41,7 @@ struct qdisc_util {
 	int (*parse_copt)(struct qdisc_util *qu, int argc,
 			  char **argv, struct nlmsghdr *n, const char *dev);
 	int (*print_copt)(struct qdisc_util *qu, FILE *f, struct rtattr *opt);
+	int (*has_block)(struct qdisc_util *qu, struct rtattr *opt, __u32 block_idx, bool *p_has);
 };
 
 extern __u16 f_proto;