FW: Sporadic permission denied error in Samba 4.3 and 4.4, 4.2 OK

Volker Lendecke vl at samba.org
Mon Nov 14 21:54:57 UTC 2016

On Mon, Nov 14, 2016 at 01:50:01PM -0800, Jeremy Allison wrote:
> On Mon, Nov 14, 2016 at 09:42:53PM +0000, Youzhong Yang wrote:
> > Yes, it's illumos/SmartOS system running Samba. It's possible there's some kind of bug either in kernel or in user-land programming. If you guys can point out a few critical points to put debug statements, I would be more than happy to debug the issue here.
> There's no magic debug that will show a kernel
> bug. If you're reporting it right, the issue is
> on 4.5.x on your kernel a sendmsg() call on a
> connected UNIX domain socket is dropping the
> message.
> That simply should not happen. For a lease break
> message this isn't anything fancy such as fd-passing,
> this should be a simple datagram message.
> Look at the test program in:
> source3/lib/unix_msg/test_source.c
> Ensure this works correctly on your kernel.
> Can you run directly out of master on a test
> system, so we know we're looking at identical
> code ?

Master has changed vastly, unix_msg.c is gone.

Also, I still have some FreeBSD-specific patches for an overload
situation: FreeBSD does not block, but instead returns ENOBUFS. We need
to a) treat ENOBUFS the same as EWOULDBLOCK in the nonblocking path,
and b) do send-polling in the thread until EWOULDBLOCK vanishes. I could
imagine something similar in Solaris too.


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