[PATCH v2] RDMA/rxe: fix the parent sysfs read when the interface has 15 chars

[Yi Zhang <yi.zhang@xxxxxxxxxx>]

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

Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
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..756980f79951 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 scnprintf(buf, PAGE_SIZE, "%s\n", rxe_parent_name(rxe, 1));
 }
 
 static DEVICE_ATTR_RO(parent);
-- 
2.21.0