[PATCH] net: tuntap: add ioctl() TUNGETQUEUEINDX to fetch queue index

[Randy Li <ayaka@soulik.info>]

We need the queue index in qdisc mapping rule. There is no way to
fetch that.

Signed-off-by: Randy Li <ayaka@soulik.info>
---
 drivers/net/tap.c           | 9 +++++++++
 drivers/net/tun.c           | 4 ++++
 include/uapi/linux/if_tun.h | 1 +
 3 files changed, 14 insertions(+)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 77574f7a3bd4..6099f27a0a1f 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -1120,6 +1120,15 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 		rtnl_unlock();
 		return ret;
 
+	case TUNGETQUEUEINDEX:
+		rtnl_lock();
+		if (!q->enabled)
+			ret = -EINVAL;
+
+		ret = put_user(q->queue_index, up);
+		rtnl_unlock();
+		return ret;
+
 	case SIOCGIFHWADDR:
 		rtnl_lock();
 		tap = tap_get_tap_dev(q);
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 1d06c560c5e6..5473a0fca2e1 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -3115,6 +3115,10 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 		return open_related_ns(&net->ns, get_net_ns);
+	} else if (cmd == TUNGETQUEUEINDEX) {
+		if (tfile->detached)
+			return -EINVAL;
+		return put_user(tfile->queue_index, (unsigned int __user*)argp);
 	}
 
 	rtnl_lock();
diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index 287cdc81c939..2668ca3b06a5 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -61,6 +61,7 @@
 #define TUNSETFILTEREBPF _IOR('T', 225, int)
 #define TUNSETCARRIER _IOW('T', 226, int)
 #define TUNGETDEVNETNS _IO('T', 227)
+#define TUNGETQUEUEINDEX _IOR('T', 228, unsigned int)
 
 /* TUNSETIFF ifr flags */
 #define IFF_TUN		0x0001
-- 
2.45.2