Description of problem:
If device_write function is called via dlm-control, file->private_data will be NULL. See ctl_device_open() in user.c. Through proc->flags is read.
Proposed upstream patch:
Created attachment 314042 [details]
Upstream patch for this issue
Verified that upstream patch 254ae43ab8d7877c980fca3636624e0777a70fa4 is implemented as commit 2636c514d9a35c7bf9d39f40c9c57849df90895d in mrt-rt-18.104.22.168-81
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.