Lidong Chen c5e76115cc migration: not wait RDMA_CM_EVENT_DISCONNECTED event after rdma_disconnect
When cancel migration during RDMA precopy, the source qemu main thread hangs sometime.

The backtrace is:
    (gdb) bt
    #0  0x00007f249eabd43d in write () from /lib64/libpthread.so.0
    #1  0x00007f24a1ce98e4 in rdma_get_cm_event (channel=0x4675d10, event=0x7ffe2f643dd0) at src/cma.c:2189
    #2  0x00000000007b6166 in qemu_rdma_cleanup (rdma=0x6784000) at migration/rdma.c:2296
    #3  0x00000000007b7cae in qio_channel_rdma_close (ioc=0x3bfcc30, errp=0x0) at migration/rdma.c:2999
    #4  0x00000000008db60e in qio_channel_close (ioc=0x3bfcc30, errp=0x0) at io/channel.c:273
    #5  0x00000000007a8765 in channel_close (opaque=0x3bfcc30) at migration/qemu-file-channel.c:98
    #6  0x00000000007a71f9 in qemu_fclose (f=0x527c000) at migration/qemu-file.c:334
    #7  0x0000000000795b96 in migrate_fd_cleanup (opaque=0x3b46280) at migration/migration.c:1162
    #8  0x000000000093a71b in aio_bh_call (bh=0x3db7a20) at util/async.c:90
    #9  0x000000000093a7b2 in aio_bh_poll (ctx=0x3b121c0) at util/async.c:118
    #10 0x000000000093f2ad in aio_dispatch (ctx=0x3b121c0) at util/aio-posix.c:436
    #11 0x000000000093ab41 in aio_ctx_dispatch (source=0x3b121c0, callback=0x0, user_data=0x0)
        at util/async.c:261
    #12 0x00007f249f73c7aa in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
    #13 0x000000000093dc5e in glib_pollfds_poll () at util/main-loop.c:215
    #14 0x000000000093dd4e in os_host_main_loop_wait (timeout=28000000) at util/main-loop.c:263
    #15 0x000000000093de05 in main_loop_wait (nonblocking=0) at util/main-loop.c:522
    #16 0x00000000005bc6a5 in main_loop () at vl.c:1944
    #17 0x00000000005c39b5 in main (argc=56, argv=0x7ffe2f6443f8, envp=0x3ad0030) at vl.c:4752

It does not get the RDMA_CM_EVENT_DISCONNECTED event after rdma_disconnect sometime.

According to IB Spec once active side send DREQ message, it should wait for DREP message
and only once it arrived it should trigger a DISCONNECT event. DREP message can be dropped
due to network issues.
For that case the spec defines a DREP_timeout state in the CM state machine, if the DREP is
dropped we should get a timeout and a TIMEWAIT_EXIT event will be trigger.
Unfortunately the current kernel CM implementation doesn't include the DREP_timeout state
and in above scenario we will not get DISCONNECT or TIMEWAIT_EXIT events.

So it should not invoke rdma_get_cm_event which may hang forever, and the event channel
is also destroyed in qemu_rdma_cleanup.

Signed-off-by: Lidong Chen <lidongchen@tencent.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2018-06-04 05:46:15 +02:00
2018-03-12 11:18:27 +01:00
2018-05-09 00:13:37 +02:00
2018-04-17 21:11:30 +01:00
2017-07-14 12:29:49 +02:00
2018-05-09 00:13:37 +02:00
2018-05-31 21:19:24 +02:00
2018-06-01 15:00:54 +01:00
2018-05-23 17:33:58 +03:00
2017-07-20 09:56:56 +02:00
2012-09-07 09:02:44 +03:00
2018-05-18 17:48:08 +01:00
2018-03-02 13:45:50 -06:00
2018-05-23 14:30:51 +02:00
2018-05-23 14:30:51 +02:00
2016-02-04 17:41:30 +00:00
2016-02-04 17:41:30 +00:00
2018-03-07 08:30:28 +13:00
2018-04-09 16:36:40 +02:00
2018-05-15 22:13:08 +02:00
2018-05-15 22:13:08 +02:00
2018-05-30 13:31:01 +02:00
2018-05-23 14:30:51 +02:00
2018-05-30 16:08:17 +01:00
2016-02-04 17:41:30 +00:00
2018-05-30 13:19:14 -03:00
2018-05-23 14:30:51 +02:00
2018-05-30 13:19:14 -03:00
2018-05-30 13:19:14 -03:00
2018-03-08 15:45:14 +00:00
2017-07-31 13:06:39 +03:00
2018-05-23 14:30:51 +02:00
2018-04-26 11:48:27 +01:00

         QEMU README
         ===========

QEMU is a generic and open source machine & userspace emulator and
virtualizer.

QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).

QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.

QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.

QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.


Building
========

QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:

  mkdir build
  cd build
  ../configure
  make

Additional information can also be found online via the QEMU website:

  https://qemu.org/Hosts/Linux
  https://qemu.org/Hosts/Mac
  https://qemu.org/Hosts/W32


Submitting patches
==================

The QEMU source code is maintained under the GIT version control system.

   git clone git://git.qemu.org/qemu.git

When submitting patches, one common approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the HACKING and CODING_STYLE files.

Additional information on submitting patches can be found online via
the QEMU website

  https://qemu.org/Contribute/SubmitAPatch
  https://qemu.org/Contribute/TrivialPatches

The QEMU website is also maintained under source control.

  git clone git://git.qemu.org/qemu-web.git
  https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/

A 'git-publish' utility was created to make above process less
cumbersome, and is highly recommended for making regular contributions,
or even just for sending consecutive patch series revisions. It also
requires a working 'git send-email' setup, and by default doesn't
automate everything, so you may want to go through the above steps
manually for once.

For installation instructions, please go to

  https://github.com/stefanha/git-publish

The workflow with 'git-publish' is:

  $ git checkout master -b my-feature
  $ # work on new commits, add your 'Signed-off-by' lines to each
  $ git publish

Your patch series will be sent and tagged as my-feature-v1 if you need to refer
back to it in the future.

Sending v2:

  $ git checkout my-feature # same topic branch
  $ # making changes to the commits (using 'git rebase', for example)
  $ git publish

Your patch series will be sent with 'v2' tag in the subject and the git tip
will be tagged as my-feature-v2.

Bug reporting
=============

The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:

  https://bugs.launchpad.net/qemu/

If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.

For additional information on bug reporting consult:

  https://qemu.org/Contribute/ReportABug


Contact
=======

The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC

 - qemu-devel@nongnu.org
   https://lists.nongnu.org/mailman/listinfo/qemu-devel
 - #qemu on irc.oftc.net

Information on additional methods of contacting the community can be
found online via the QEMU website:

  https://qemu.org/Contribute/StartHere

-- End
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Original Xbox Emulator for Windows, macOS, and Linux (Active Development)
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