parent sysfs reads will yield '\0' bytes when the interface name has 15 chars, and there will no "\n" output. reproducer: Create one interface with 15 chars [root@test ~]# ip a s enp0s29u1u7u3c2 2: enp0s29u1u7u3c2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000 link/ether 02:21:28:57:47:17 brd ff:ff:ff:ff:ff:ff inet6 fe80::ac41:338f:5bcd:c222/64 scope link noprefixroute valid_lft forever preferred_lft forever [root@test ~]# modprobe rdma_rxe [root@test ~]# echo enp0s29u1u7u3c2 > /sys/module/rdma_rxe/parameters/add [root@test ~]# cat /sys/class/infiniband/rxe0/parent enp0s29u1u7u3c2[root@test ~]# [root@test ~]# f="/sys/class/infiniband/rxe0/parent" [root@test ~]# echo "$(<"$f")" -bash: warning: command substitution: ignored null byte in input enp0s29u1u7u3c2 Signed-off-by: Yi Zhang <yi.zhang@xxxxxxxxxx> --- drivers/infiniband/sw/rxe/rxe_verbs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c index bb61e534e468..91090cb1b08c 100644 --- a/drivers/infiniband/sw/rxe/rxe_verbs.c +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c @@ -1056,7 +1056,7 @@ static ssize_t parent_show(struct device *device, struct rxe_dev *rxe = rdma_device_to_drv_device(device, struct rxe_dev, ib_dev); - return snprintf(buf, 16, "%s\n", rxe_parent_name(rxe, 1)); + return snprintf(buf, 17, "%s\n", rxe_parent_name(rxe, 1)); } static DEVICE_ATTR_RO(parent); -- 2.21.0