Re: [Qemu-devel] [PATCH v6 4/4] sockets: Handle race condition between binds to the same port

["Daniel P. Berrange" <berrange@redhat.com>]

On Sat, Jul 29, 2017 at 11:18:18PM +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.
> 
> Also clean up some issues with error handling to allow more
> accurate reporting of the cause of an error.
> 
> 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.
> 
> Reviewed-by: Bhavesh Davda <bhavesh.davda@oracle.com>
> Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
> Reviewed-by: Girish Moodalbail <girish.moodalbail@oracle.com>
> Signed-off-by: Knut Omang <knut.omang@oracle.com>
> ---
>  tests/Makefile.include |  2 +-
>  util/qemu-sockets.c    | 58 ++++++++++++++++++++++++++++++-------------
>  2 files changed, 42 insertions(+), 18 deletions(-)

Reviewed-by: Daniel P. Berrange <berrange@redhat.com>


Regards,
Daniel
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