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| -rw-r--r-- | Documentation/networking/tuntap.txt | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/Documentation/networking/tuntap.txt b/Documentation/networking/tuntap.txt index c0aab985bad..949d5dcdd9a 100644 --- a/Documentation/networking/tuntap.txt +++ b/Documentation/networking/tuntap.txt @@ -105,6 +105,83 @@ Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com> Proto [2 bytes] Raw protocol(IP, IPv6, etc) frame. + 3.3 Multiqueue tuntap interface: + + From version 3.8, Linux supports multiqueue tuntap which can uses multiple + file descriptors (queues) to parallelize packets sending or receiving. The + device allocation is the same as before, and if user wants to create multiple + queues, TUNSETIFF with the same device name must be called many times with + IFF_MULTI_QUEUE flag. + + char *dev should be the name of the device, queues is the number of queues to + be created, fds is used to store and return the file descriptors (queues) + created to the caller. Each file descriptor were served as the interface of a + queue which could be accessed by userspace. + + #include <linux/if.h> + #include <linux/if_tun.h> + + int tun_alloc_mq(char *dev, int queues, int *fds) + { + struct ifreq ifr; + int fd, err, i; + + if (!dev) + return -1; + + memset(&ifr, 0, sizeof(ifr)); + /* Flags: IFF_TUN - TUN device (no Ethernet headers) + * IFF_TAP - TAP device + * + * IFF_NO_PI - Do not provide packet information + * IFF_MULTI_QUEUE - Create a queue of multiqueue device + */ + ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_MULTI_QUEUE; + strcpy(ifr.ifr_name, dev); + + for (i = 0; i < queues; i++) { + if ((fd = open("/dev/net/tun", O_RDWR)) < 0) + goto err; + err = ioctl(fd, TUNSETIFF, (void *)&ifr); + if (err) { + close(fd); + goto err; + } + fds[i] = fd; + } + + return 0; + err: + for (--i; i >= 0; i--) + close(fds[i]); + return err; + } + + A new ioctl(TUNSETQUEUE) were introduced to enable or disable a queue. When + calling it with IFF_DETACH_QUEUE flag, the queue were disabled. And when + calling it with IFF_ATTACH_QUEUE flag, the queue were enabled. The queue were + enabled by default after it was created through TUNSETIFF. + + fd is the file descriptor (queue) that we want to enable or disable, when + enable is true we enable it, otherwise we disable it + + #include <linux/if.h> + #include <linux/if_tun.h> + + int tun_set_queue(int fd, int enable) + { + struct ifreq ifr; + + memset(&ifr, 0, sizeof(ifr)); + + if (enable) + ifr.ifr_flags = IFF_ATTACH_QUEUE; + else + ifr.ifr_flags = IFF_DETACH_QUEUE; + + return ioctl(fd, TUNSETQUEUE, (void *)&ifr); + } + Universal TUN/TAP device driver Frequently Asked Question. 1. What platforms are supported by TUN/TAP driver ? |