netdev - [patch iproute2 net-next v9 2/4] tc: introduce tc_qdisc_block

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Date:   Tue, 16 Jan 2018 14:35:26 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jhs@...atatu.com, xiyou.wangcong@...il.com,
        mlxsw@...lanox.com, andrew@...n.ch,
        vivien.didelot@...oirfairelinux.com, f.fainelli@...il.com,
        michael.chan@...adcom.com, ganeshgr@...lsio.com,
        saeedm@...lanox.com, matanb@...lanox.com, leonro@...lanox.com,
        idosch@...lanox.com, jakub.kicinski@...ronome.com,
        simon.horman@...ronome.com, pieter.jansenvanvuuren@...ronome.com,
        john.hurley@...ronome.com, alexander.h.duyck@...el.com,
        ogerlitz@...lanox.com, john.fastabend@...il.com,
        daniel@...earbox.net, dsahern@...il.com, roopa@...ulusnetworks.com
Subject: [patch iproute2 net-next v9 2/4] tc: introduce tc_qdisc_block_exists helper

From: Jiri Pirko <jiri@...lanox.com>

This hepler used qdisc dump to list all qdisc and find if block index in
question is used by any of them. That means the block with specified
index exists.

Signed-off-by: Jiri Pirko <jiri@...lanox.com>
---
 tc/tc_qdisc.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tc/tc_util.h  |  2 ++
 2 files changed, 63 insertions(+)

diff --git a/tc/tc_qdisc.c b/tc/tc_qdisc.c
index 70279b9..3f91558 100644
--- a/tc/tc_qdisc.c
+++ b/tc/tc_qdisc.c
@@ -412,3 +412,64 @@ int do_qdisc(int argc, char **argv)
 	fprintf(stderr, "Command \"%s\" is unknown, try \"tc qdisc help\".\n", *argv);
 	return -1;
 }
+
+struct tc_qdisc_block_exists_ctx {
+	__u32 block_index;
+	bool found;
+};
+
+static int tc_qdisc_block_exists_cb(const struct sockaddr_nl *who,
+				    struct nlmsghdr *n, void *arg)
+{
+	struct tc_qdisc_block_exists_ctx *ctx = arg;
+	struct tcmsg *t = NLMSG_DATA(n);
+	int len = n->nlmsg_len;
+	struct rtattr *tb[TCA_MAX+1];
+
+	if (n->nlmsg_type != RTM_NEWQDISC)
+		return 0;
+
+	len -= NLMSG_LENGTH(sizeof(*t));
+	if (len < 0)
+		return -1;
+
+	parse_rtattr(tb, TCA_MAX, TCA_RTA(t), len);
+
+	if (tb[TCA_KIND] == NULL)
+		return -1;
+
+	if (tb[TCA_INGRESS_BLOCK] &&
+	    RTA_PAYLOAD(tb[TCA_INGRESS_BLOCK]) >= sizeof(__u32)) {
+		__u32 block = rta_getattr_u32(tb[TCA_INGRESS_BLOCK]);
+
+		if (block && block == ctx->block_index)
+			ctx->found = true;
+	}
+
+	if (tb[TCA_EGRESS_BLOCK] &&
+	    RTA_PAYLOAD(tb[TCA_EGRESS_BLOCK]) >= sizeof(__u32)) {
+		__u32 block = rta_getattr_u32(tb[TCA_EGRESS_BLOCK]);
+
+		if (block && block == ctx->block_index)
+			ctx->found = true;
+	}
+	return 0;
+}
+
+int tc_qdisc_block_exists(__u32 block_index)
+{
+	struct tc_qdisc_block_exists_ctx ctx = { .block_index = block_index };
+	struct tcmsg t = { .tcm_family = AF_UNSPEC };
+
+	if (rtnl_dump_request(&rth, RTM_GETQDISC, &t, sizeof(t)) < 0) {
+		perror("Cannot send dump request");
+		return false;
+	}
+
+	if (rtnl_dump_filter(&rth, tc_qdisc_block_exists_cb, &ctx) < 0) {
+		perror("Dump terminated\n");
+		return false;
+	}
+
+	return ctx.found;
+}
diff --git a/tc/tc_util.h b/tc/tc_util.h
index 1218610..72f4282 100644
--- a/tc/tc_util.h
+++ b/tc/tc_util.h
@@ -132,4 +132,6 @@ int prio_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt);
 int cls_names_init(char *path);
 void cls_names_uninit(void);
 
+int tc_qdisc_block_exists(__u32 block_index);
+
 #endif
-- 
2.9.5