From b5235d61f3b7d2b1c2b9ee2601f3aca2b151b508 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Fri, 11 Jan 2019 12:35:18 -0800 Subject: [PATCH] net/tap: let kernel choose tun device name Assigning tun and tap index in DPDK tap device driver is racy and fails if used with primary/secondary. Instead use the kernel feature of device wildcarding where if a name with %d is used the kernel will fill in the next available device. Fixes: 02f96a0a82d1 ("net/tap: add TUN/TAP device PMD") Cc: stable@dpdk.org Reported-by: Haifeng Li Signed-off-by: Stephen Hemminger Acked-by Keith Wiles --- drivers/net/tap/rte_eth_tap.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c index d699b4fb09..ed8483cb96 100644 --- a/drivers/net/tap/rte_eth_tap.c +++ b/drivers/net/tap/rte_eth_tap.c @@ -79,9 +79,6 @@ static const char *valid_arguments[] = { NULL }; -static unsigned int tap_unit; -static unsigned int tun_unit; - static char tuntap_name[8]; static volatile uint32_t tap_trigger; /* Rx trigger */ @@ -151,8 +148,6 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive) IFF_TAP : IFF_TUN | IFF_POINTOPOINT; strlcpy(ifr.ifr_name, pmd->name, IFNAMSIZ); - TAP_LOG(DEBUG, "ifr_name '%s'", ifr.ifr_name); - fd = open(TUN_TAP_DEV_PATH, O_RDWR); if (fd < 0) { TAP_LOG(ERR, "Unable to create %s interface", tuntap_name); @@ -186,6 +181,13 @@ tun_alloc(struct pmd_internals *pmd, int is_keepalive) goto error; } + /* + * Name passed to kernel might be wildcard like dtun%d + * and need to find the resulting device. + */ + TAP_LOG(DEBUG, "Device name is '%s'", ifr.ifr_name); + strlcpy(pmd->name, ifr.ifr_name, RTE_ETH_NAME_MAX_LEN); + if (is_keepalive) { /* * Detach the TUN/TAP keep-alive queue @@ -1756,6 +1758,7 @@ eth_dev_tap_create(struct rte_vdev_device *vdev, char *tap_name, TAP_LOG(ERR, "Unable to create %s interface", tuntap_name); goto error_exit; } + TAP_LOG(DEBUG, "allocated %s", pmd->name); ifr.ifr_mtu = dev->data->mtu; if (tap_ioctl(pmd, SIOCSIFMTU, &ifr, 1, LOCAL_AND_REMOTE) < 0) @@ -1918,8 +1921,8 @@ set_interface_name(const char *key __rte_unused, } strlcpy(name, value, RTE_ETH_NAME_MAX_LEN); } else { - snprintf(name, RTE_ETH_NAME_MAX_LEN, "%s%d", - DEFAULT_TAP_NAME, tap_unit - 1); + /* use tap%d which causes kernel to choose next available */ + strlcpy(name, DEFAULT_TAP_NAME "%d", RTE_ETH_NAME_MAX_LEN); } return 0; } @@ -2032,8 +2035,8 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev) return 0; } - snprintf(tun_name, sizeof(tun_name), "%s%u", - DEFAULT_TUN_NAME, tun_unit++); + /* use tun%d which causes kernel to choose next available */ + strlcpy(tun_name, DEFAULT_TUN_NAME "%d", RTE_ETH_NAME_MAX_LEN); if (params && (params[0] != '\0')) { TAP_LOG(DEBUG, "parameters (%s)", params); @@ -2053,17 +2056,15 @@ rte_pmd_tun_probe(struct rte_vdev_device *dev) } pmd_link.link_speed = ETH_SPEED_NUM_10G; - TAP_LOG(DEBUG, "Initializing pmd_tun for %s as %s", - name, tun_name); + TAP_LOG(DEBUG, "Initializing pmd_tun for %s", name); ret = eth_dev_tap_create(dev, tun_name, remote_iface, 0, - ETH_TUNTAP_TYPE_TUN); + ETH_TUNTAP_TYPE_TUN); leave: if (ret == -1) { TAP_LOG(ERR, "Failed to create pmd for %s as %s", name, tun_name); - tun_unit--; /* Restore the unit number */ } rte_kvargs_free(kvlist); @@ -2219,8 +2220,9 @@ rte_pmd_tap_probe(struct rte_vdev_device *dev) } speed = ETH_SPEED_NUM_10G; - snprintf(tap_name, sizeof(tap_name), "%s%u", - DEFAULT_TAP_NAME, tap_unit++); + + /* use tap%d which causes kernel to choose next available */ + strlcpy(tap_name, DEFAULT_TAP_NAME "%d", RTE_ETH_NAME_MAX_LEN); memset(remote_iface, 0, RTE_ETH_NAME_MAX_LEN); if (params && (params[0] != '\0')) { @@ -2283,7 +2285,6 @@ leave: rte_mp_action_unregister(TAP_MP_KEY); tap_devices_count--; } - tap_unit--; /* Restore the unit number */ } rte_kvargs_free(kvlist); -- 2.20.1