[PVE-User] PVE 4.2 /sys/class write permission gone?

[Chris Hsiang]

Hi All,

After I upgrade to PVE 4.2, I realized that all write permission under 
/sys/class is gone even through ls -al shows root should have write 
permission

Please pay attention to add_target

root at vm-ha:/sys/class/infiniband_srp/srp-mlx4_0-1# ls -al
total 0
drwxr-xr-x 3 root root    0 Apr 30 10:10 .
drwxr-xr-x 4 root root    0 Apr 30 10:19 ..
--w------- 1 root root 4096 Apr 30 10:20 add_target
lrwxrwxrwx 1 root root    0 Apr 30 10:18 device -> ../../../0000:0a:00.0
-r--r--r-- 1 root root 4096 Apr 30 10:21 ibdev
-r--r--r-- 1 root root 4096 Apr 30 10:21 port
drwxr-xr-x 2 root root    0 Apr 30 10:21 power
lrwxrwxrwx 1 root root    0 Apr 30 10:21 subsystem -> ../../../../../../class/infiniband_srp
-rw-r--r-- 1 root root 4096 Apr 30 10:10 uevent
root at vm-ha:/sys/class/infiniband_srp/srp-mlx4_0-1#

root at vm-ha:/sys/class/infiniband_srp/srp-mlx4_0-1# echo "id_ext=0002c90300a0b670,ioc_guid=0002c90300a0b670,dgid=fe800000000000000002c90300a0b671,pkey=ffff,service_id=0002c90300a0b670" > /sys/class/infiniband_srp/srp-mlx4_0-1/add_target
bash: echo: write error: Connection reset by peer

This does not only apply to infiniband class, but also "net" class as 
well as I have Intel i350 NIC which uses igb driver and also Intel X520 
& x552 NIC uses ixgbe driver, they all cannot use echo 4 > 
/sys/class/net/../max_vfs to enable sriov

Chris