[asterisk-bugs] [JIRA] (DAHLIN-343) Dynamic span modules fail to decrement reference counter for the underlying VLAN interface when unloading

[Assen Totin (JIRA)]

Assen Totin created DAHLIN-343:
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             Summary: Dynamic span modules fail to decrement reference counter for the underlying VLAN interface when unloading
                 Key: DAHLIN-343
                 URL: https://issues.asterisk.org/jira/browse/DAHLIN-343
             Project: DAHDI-Linux
          Issue Type: Bug
      Security Level: None
          Components: dahdi_dynamic, dahdi_dynamic_eth
    Affects Versions: 2.10.0
         Environment: Linux 2.6
            Reporter: Assen Totin
            Assignee: Russ Meyerriecks
            Severity: Minor


Scope: the issue is present only when a dynamic span is configured on top of a IEEE 802.1q interface (VLAN interface). 

Effect: when a dynamic span is configured on top of a VLAN interface (e.g., eth0.N) and is later removed, unloading the modules (dahdi_dynamic_eth, dahdi_dynamic) does not decrement the kernel reference counter for the underlying VLAN interface. As a result, the kernel believes the underlying network interface is still in use, refusing to remove it upon network shutdown. The latter means that clean power-off of the Linux OS become impossible and power cycle is almost the only remaining option (especially for remote machines and VMs). 

Notes: The effect is present only on VLAN interfaces and is not present on regular interfaces (e.g., eth0). Tested only on Linux; because Linux handles network devices differently than most other UNIX, it is likely limited to Linux. 

Testbed: confirmed on CentOS 5 and 6 VM in ESXi 5.5 with either VMXNET3 or emulated Intel EEPRO 1000 network adapters.



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