A file descriptor opened for /dev/net/tun and a tun device are
connected with ioctl. Though understanding the connection is
important for trouble shooting, no way is given to a user to know
the connected device for a given file descriptor at userland.
This patch adds a new fdinfo field for the device name connected to
a file descriptor opened for /dev/net/tun.
Here is an example of the field:
# lsof | grep tun
qemu-syst 4565 qemu 25u CHR 10,200 0t138 12921 /dev/net/tun
...
# cat /proc/4565/fdinfo/25
pos: 138
flags: 0104002
iff: vnet0
# ip link show dev vnet0
8: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 ...
changelog:
v2: indent iff just like the other fdinfo fields are.
v3: remove unused variable.
Both are suggested by David Miller <davem@davemloft.net>.
Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
93e14b6d77