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

[Daniel P. Berrange]

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 <address@hidden>
> Reviewed-by: Bhavesh Davda <address@hidden>
> Reviewed-by: Yuval Shaia <address@hidden>
> Reviewed-by: Girish Moodalbail <address@hidden>
> ---
>  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

Regards,
Daniel
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