Re: [Qemu-devel] [PATCH 2/2] socket: Handle race condition between binds to the same port

[Knut Omang <knut.omang@oracle.com>]

On Wed, 2017-06-14 at 09:17 +0100, Daniel P. Berrange wrote:
> On Fri, Jun 09, 2017 at 09:19:49PM +0200, Knut Omang wrote:
> > If an offset of ports is specified to the inet_listen_saddr function(),
> > and two or more processes tries to bind from these ports at the same time,
> > occasionally more than one process may be able to bind to the same
> > port. The condition is detected by listen() but too late to avoid a failure.
> > 
> > This function is called by socket_listen() and used
> > by all socket listening code in QEMU, so all cases where any form of dynamic
> > port selection is used should be subject to this issue.
> > 
> > Add code to close and re-establish the socket when this
> > condition is observed, hiding the race condition from the user.
> > 
> > This has been developed and tested by means of the
> > test-listen unit test in the previous commit.
> > Enable the test for make check now that it passes.
> > 
> > Signed-off-by: Knut Omang <knut.omang@oracle.com>
> > Reviewed-by: Bhavesh Davda <bhavesh.davda@oracle.com>
> > Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
> > Reviewed-by: Girish Moodalbail <girish.moodalbail@oracle.com>
> > ---
> >  tests/Makefile.include |   2 +-
> >  util/qemu-sockets.c    | 106 +++++++++++++++++++++++++++++-------------
> >  2 files changed, 76 insertions(+), 32 deletions(-)
> 
> FYI, the changes here will conflict with a pull request that I have
> pending, so please rebase against this PR
> 
> https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg01940.html

Ok, v3 will be from this base,

Knut

> 
> Regards,
> Daniel