From: Marc-André Lureau <marcandre.lur...@redhat.com> Hi,
Since 'vhost-user: simple reconnection support' has been 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. There are also code paths that are wrong, see "don't assume opaque is a fd" patch for an example. Once those patches are reviewed & merged, they are good candidates for stable too. 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. The errors are reported up to vhost.c, as the vhost-user backend alone doesn't handle disconnected state transparently so far. There are still problematic code paths left after this series, for example, starting a migration with a disconnected backend will abort(). It is likely that other problematic code path exists (vhost_scsi_start failure is fatal, but there are no vhost-user backend that I know yet). 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). Since there is feature checks on reconnection, qemu should wait for the initial connection feature negotiation to complete. The test added demonstrates this. Additionally, a regression was found during v2, which could have been spotted with a multiqueue test, so add a basic one that would have exhibited the issue. For convenience, the series is also available on: https://github.com/elmarco/qemu, branch vhost-user-reconnect v5: - rebased - use a VHOST_OPS_DEBUG macro to print vhost_ops errors - replace assert(foo != NULL) with assert(foo) - add "RFC: vhost: do not update last avail idx" v4: - change notify_migration_done() patch to be VHOST_BACKEND_TYPE_USER specific, to avoid having to handle the case where the backend doesn't implement the callback - change vhost_dev_cleanup() to assert on empty log, instead of adding a call to vhost_log_put() - made "keep vhost_net after a disconnection" more robust, got rid of the acked_features field - improve commit log, and some patch reorganization for clarity v3: - add vhost-user multiqueue test, which would have helped to find the following fix - fix waiting on vhost-user connection with multiqueue (found by Yuanhan Liu) - merge vhost_user_{read,write}() error checking patches - add error reporting to vhost_user_read() (similar to vhost_user_write()) - add a vhost_net_set_backend() wrapper to help with potential crash - some leak fixes v2: - some patch ordering: minor fix, close(fd) fix, assert/fprintf->error_report, check and return error, vhost_dev_cleanup() fixes, keep vhost_net after a disconnect, wait until connection is ready - merge read/write error checks - do not rely on link state to check vhost-user init completed Marc-André Lureau (31): misc: indentation vhost-user: minor simplification vhost: don't assume opaque is a fd, use backend cleanup vhost: make vhost_log_put() idempotent vhost: assert the log was cleaned up vhost: fix cleanup on not fully initialized device vhost: make vhost_dev_cleanup() idempotent vhost-net: always call vhost_dev_cleanup() on failure vhost: fix calling vhost_dev_cleanup() after vhost_dev_init() vhost: do not assert() on vhost_ops failure vhost: add missing VHOST_OPS_DEBUG vhost: use error_report() instead of fprintf(stderr,...) qemu-char: fix qemu_chr_fe_set_msgfds() crash when disconnected vhost-user: call set_msgfds unconditionally vhost-user: check qemu_chr_fe_set_msgfds() return value vhost-user: check vhost_user_{read,write}() return value vhost-user: keep vhost_net after a disconnection vhost-user: add get_vhost_net() assertions Revert "vhost-net: do not crash if backend is not present" vhost-net: vhost_migration_done is vhost-user specific 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 backend init is completed tests: plug some leaks in virtio-net-test tests: fix vhost-user-test leak tests: add /vhost-user/connect-fail test tests: add a simple /vhost-user/multiqueue test vhost-user: add error report in vhost_user_write() vhost: add vhost_net_set_backend() RFC: vhost: do not update last avail idx on get_vring_base() failure hw/net/vhost_net.c | 34 ++++------ hw/virtio/vhost-user.c | 67 ++++++++++++++------ hw/virtio/vhost.c | 158 ++++++++++++++++++++++++++++++---------------- include/hw/virtio/vhost.h | 4 ++ include/sysemu/char.h | 8 +++ net/tap.c | 1 + net/vhost-user.c | 59 ++++++++++------- qemu-char.c | 82 +++++++++++++++++------- tests/Makefile.include | 2 +- tests/vhost-user-test.c | 147 +++++++++++++++++++++++++++++++++++++++++- tests/virtio-net-test.c | 12 +++- 11 files changed, 422 insertions(+), 152 deletions(-) -- 2.9.0
