Re: [Qemu-devel] [PATCH 00/24] vhost-user reconnect fixes

[Michael S. Tsirkin]

On Tue, Jun 21, 2016 at 12:02:28PM +0200, address@hidden wrote:
> From: Marc-André Lureau <address@hidden>
> 
> Hi,
> 
> Since 'vhost-user: simple reconnection support' was merged, it is
> possible to disconnect and reconnect a vhost-user backend. However,
> many code paths in qemu may trigger assert() when the backend is
> disconnected.
> 
> Some assert() could simply be replaced by error_report() or silently
> fail since they are recoverable cases. Some missing error checks can
> also help prevent later issues. In many cases, the code assumes
> get_vhost_net() will be non-NULL after a succesful connection, so I
> changed it to stay after a disconnect until the new connection comes
> (as suggested by Michael). There are also code paths that are wrong,
> see "don't assume opaque is a fd" patch for an example.

Can this be rarranged, first patches fixing the code paths that are wrong,
then patches handling the asserts etc?

> Since there is feature checks on reconnection, qemu should wait for
> the initial connection feature negotiation to complete. The test added
> demonstrates this.
> 
> For convenience, the series is also available on:
> https://github.com/elmarco/qemu, branch vhost-user-reconnect
> 
> Marc-André Lureau (24):
>   misc: indentation
>   vhost-user: minor simplification
>   qemu-char: check socket is actually connected
>   vhost-user: check qemu_chr_fe_set_msgfds() return value
>   vhost: change some assert() for error_report() or silent fail
>   vhost-user: check vhost_user_write() return value
>   vhost: use error_report() instead of fprintf(stderr,...)
>   vhost-user: return a read error
>   vhost: make vhost_log_put() idempotent
>   vhost: call vhost_log_put() on cleanup
>   vhost: add vhost device only after all success
>   vhost: make vhost_dev_cleanup() idempotent
>   vhost-net: always call vhost_dev_cleanup() on failure
>   vhost: don't assume opaque is a fd, use backend cleanup
>   vhost: fix calling vhost_dev_cleanup() after vhost_dev_init()
>   vhost-user: keep vhost_net after a disconnection
>   Revert "vhost-net: do not crash if backend is not present"
>   get_vhost_net() should be != null after vhost_user_init
>   vhost-net: success if backend has no ops->vhost_migration_done
>   vhost: add assert() to check runtime behaviour
>   char: add chr_wait_connected callback
>   char: add and use tcp_chr_wait_connected
>   vhost-user: wait until link is up
>   tests: add /vhost-user/connect-fail test
> 
>  hw/net/vhost_net.c      |  19 +++-----
>  hw/virtio/vhost-user.c  |  54 +++++++++++++++--------
>  hw/virtio/vhost.c       | 114 
> +++++++++++++++++++++++++++---------------------
>  include/sysemu/char.h   |   8 ++++
>  net/tap.c               |   1 +
>  net/vhost-user.c        |  36 ++++++++-------
>  qemu-char.c             |  82 ++++++++++++++++++++++++----------
>  tests/vhost-user-test.c |  37 ++++++++++++++++
>  8 files changed, 233 insertions(+), 118 deletions(-)
> 
> -- 
> 2.7.4