On 30.10.19 19:06, Anthony PERARD wrote:
Patch series available in this git branch:
https://xenbits.xen.org/git-http/people/aperard/xen-unstable.git
br.fix-ev_qmp-multi-connect-v2
Hi,
QEMU's QMP socket doesn't allow multiple concurrent connection. Also, it
listen() on the socket with a `backlog' of only 1. On Linux at least, once that
backlog is filled connect() will return EAGAIN if the socket fd is
non-blocking. libxl may attempt many concurrent connect() attempt if for
example a guest is started with several PCI passthrough devices, and a
connect() failure lead to a failure to start the guest.
Since we can't change the listen()'s `backlog' that QEMU use, we need other
ways to workaround the issue. This patch series introduce a lock to acquire
before attempting to connect() to the QMP socket. Since the lock might be held
for to long, the series also introduce a way to cancel the acquisition of the
lock, this means killing the process that tries to get the lock.
See thread[1] for discussed alternative.
[1] https://lists.xenproject.org/archives/html/xen-devel/2019-10/msg01815.html
Cheers,
Anthony PERARD (6):
libxl: Introduce libxl__ev_child_kill_deregister
libxl: Move libxl__ev_devlock declaration
libxl: Rename ev_devlock to ev_slowlock
libxl: Introduce libxl__ev_slowlock_dispose
libxl: libxl__ev_qmp_send now takes an egc
libxl_qmp: Have a lock for QMP socket access
tools/libxl/libxl_disk.c | 16 ++--
tools/libxl/libxl_dm.c | 8 +-
tools/libxl/libxl_dom_save.c | 2 +-
tools/libxl/libxl_dom_suspend.c | 2 +-
tools/libxl/libxl_domain.c | 18 ++---
tools/libxl/libxl_event.c | 6 +-
tools/libxl/libxl_fork.c | 48 ++++++++++++
tools/libxl/libxl_internal.c | 41 +++++++---
tools/libxl/libxl_internal.h | 130 +++++++++++++++++++-------------
tools/libxl/libxl_pci.c | 8 +-
tools/libxl/libxl_qmp.c | 119 ++++++++++++++++++++++++-----
tools/libxl/libxl_usb.c | 28 ++++---
12 files changed, 301 insertions(+), 125 deletions(-)
For the series:
Release-acked-by: Juergen Gross <jgr...@suse.com>
Juergen
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