Set non blocking on /dev/rdma_cm

KrishnamRaju ErapaRaju Krishna2 at
Wed Aug 17 07:03:16 UTC 2016

Hi Alex, 

I too faced the same issue earlier.  But could not look into it/report it due to other priorities.

Hans, if you have root caused it please point me to the patch, few of my apps uses O_NONBLOCK.


-----Original Message-----
From: owner-freebsd-infiniband at [mailto:owner-freebsd-infiniband at] On Behalf Of Alex Bowden
Sent: Wednesday, August 17, 2016 1:54 AM
To: freebsd-infiniband at
Subject: Set non blocking on /dev/rdma_cm

Hi all,

I've modified rping to set O_NONBLOCKING on /dev/rdma_cm on the event channel (rdma_create_event_channel) which fails like this:

  9997 rping    CALL  openat(AT_FDCWD,0x800a42708,0x100002<O_RDWR|O_CLOEXEC>,<unused>0)
  9997 rping    NAMI  "/dev/rdma_cm"
  9997 rping    RET   openat 3

  9997 rping    CALL  fcntl(0x3,F_SETFL,0x6<O_RDWR|O_NONBLOCK>)
  9997 rping    RET   fcntl -1 errno 25 Inappropriate ioctl for device

Is this not supported for some reason? This is with the latest OFED v3.2 patches by Hans.

The manpage for rdma_create_event_channel seems to state you can set non-blocking on it.


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