[Cluster-devel] problem about dlm posix file lock (sorry for missing subjuct)

[David Teigland <teigland@redhat.com>]

On Tue, Oct 13, 2015 at 04:30:53AM -0600, Zhen Ren wrote:
> It expects alarm timeout to send SIGALRM, and wake up the sleep process,
> as "man fcntl" says: "If a  signal  is  caught  while waiting,  then
> the call is interrupted and (after the signal handler has returned)
> returns immediately (with return value -1 and errno set to EINTR".

Hi, thanks for investigating this.  Have you verified that SIGALRM
interrupts the process on a local fs?  Is it any signal?  Is this causing
problems for a real program?

> dlm_posix_lock -> wait_event_killable
> And wait_event_killable will put process into "TASK_KILLABLE" state
> which's like "UNINTERRUPTABLE" but can be waked up by fatal signals. I
> did some tests, SIGTERM can did it, but SIGALRM cannot.

Perhaps we should replace that wait_event_killable with
wait_event_interruptible.  Could you recompile with that change and see if
it does what you want?

> Did this go against posix file lock semanteme? Any hints would be very
> appreciated!  I can provide any infos as I can if needed;-)

Posix locks on a cluster file system are always going to behave somewhat
differently than a local fs, but this may be a case where the difference
can be easily avoided with the change above.  Changing the behavior after
so long is a slightly concerning, though.

Dave