9476654bd5
By re-attaching RX, TX, and CTL rings during connect() rather than assuming they are freshly allocated (i.e. assuming the counters are zero), and avoiding forcing state to Closed in netback_remove() it is possible for vif instances to be unbound and re-bound from and to (respectively) a running guest. Dynamic unbind/bind is a highly useful feature for a backend module as it allows it to be unloaded and re-loaded (i.e. updated) without requiring domUs to be halted. This has been tested by running iperf as a server in the test VM and then running a client against it in a continuous loop, whilst also running: while true; do echo vif-$DOMID-$VIF >unbind; echo down; rmmod xen-netback; echo unloaded; modprobe xen-netback; cd $(pwd); brctl addif xenbr0 vif$DOMID.$VIF; ip link set vif$DOMID.$VIF up; echo up; sleep 5; done in dom0 from /sys/bus/xen-backend/drivers/vif to continuously unbind, unload, re-load, re-bind and re-plumb the backend. Clearly a performance drop was seen but no TCP connection resets were observed during this test and moreover a parallel SSH connection into the guest remained perfectly usable throughout. Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: Wei Liu <wei.liu@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.