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Stefan Hajnoczi 59c9f437c5 aio-posix: honor is_external in AioContext polling
AioHandlers marked ->is_external must be skipped when aio_node_check()
fails.  bdrv_drained_begin() needs this to prevent dataplane from
submitting new I/O requests while another thread accesses the device and
relies on it being quiesced.

This patch fixes the following segfault:

  Program terminated with signal SIGSEGV, Segmentation fault.
  #0  0x00005577f6127dad in bdrv_io_plug (bs=0x5577f7ae52f0) at qemu/block/io.c:2650
  2650            bdrv_io_plug(child->bs);
  [Current thread is 1 (Thread 0x7ff5c4bd1c80 (LWP 10917))]
  (gdb) bt
  #0  0x00005577f6127dad in bdrv_io_plug (bs=0x5577f7ae52f0) at qemu/block/io.c:2650
  #1  0x00005577f6114363 in blk_io_plug (blk=0x5577f7b8ba20) at qemu/block/block-backend.c:1561
  #2  0x00005577f5d4091d in virtio_blk_handle_vq (s=0x5577f9ada030, vq=0x5577f9b3d2a0) at qemu/hw/block/virtio-blk.c:589
  #3  0x00005577f5d4240d in virtio_blk_data_plane_handle_output (vdev=0x5577f9ada030, vq=0x5577f9b3d2a0) at qemu/hw/block/dataplane/virtio-blk.c:158
  #4  0x00005577f5d88acd in virtio_queue_notify_aio_vq (vq=0x5577f9b3d2a0) at qemu/hw/virtio/virtio.c:1304
  #5  0x00005577f5d8aaaf in virtio_queue_host_notifier_aio_poll (opaque=0x5577f9b3d308) at qemu/hw/virtio/virtio.c:2134
  #6  0x00005577f60ca077 in run_poll_handlers_once (ctx=0x5577f79ddbb0) at qemu/aio-posix.c:493
  #7  0x00005577f60ca268 in try_poll_mode (ctx=0x5577f79ddbb0, blocking=true) at qemu/aio-posix.c:569
  #8  0x00005577f60ca331 in aio_poll (ctx=0x5577f79ddbb0, blocking=true) at qemu/aio-posix.c:601
  #9  0x00005577f612722a in bdrv_flush (bs=0x5577f7c20970) at qemu/block/io.c:2403
  #10 0x00005577f60c1b2d in bdrv_close (bs=0x5577f7c20970) at qemu/block.c:2322
  #11 0x00005577f60c20e7 in bdrv_delete (bs=0x5577f7c20970) at qemu/block.c:2465
  #12 0x00005577f60c3ecf in bdrv_unref (bs=0x5577f7c20970) at qemu/block.c:3425
  #13 0x00005577f60bf951 in bdrv_root_unref_child (child=0x5577f7a2de70) at qemu/block.c:1361
  #14 0x00005577f6112162 in blk_remove_bs (blk=0x5577f7b8ba20) at qemu/block/block-backend.c:491
  #15 0x00005577f6111b1b in blk_remove_all_bs () at qemu/block/block-backend.c:245
  #16 0x00005577f60c1db6 in bdrv_close_all () at qemu/block.c:2382
  #17 0x00005577f5e60cca in main (argc=20, argv=0x7ffea6eb8398, envp=0x7ffea6eb8440) at qemu/vl.c:4684

The key thing is that bdrv_close() uses bdrv_drained_begin() and
virtio_queue_host_notifier_aio_poll() must not be called.

Thanks to Fam Zheng <famz@redhat.com> for identifying the root cause of
this crash.

Reported-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Tested-by: Alberto Garcia <berto@igalia.com>
Message-id: 20170124095350.16679-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-01-26 10:02:33 +00:00
audio trace-events: fix first line comment in trace-events 2016-08-12 10:36:01 +01:00
backends monitor: fix qmp/hmp query-memdev not reporting IDs of memory backends 2017-01-12 15:35:06 -02:00
block migration: disallow migrate_add_blocker during migration 2017-01-24 18:00:30 +00:00
bsd-user translate-all: add DEBUG_LOCKING asserts 2016-10-31 10:24:45 +01:00
contrib contrib: add libvhost-user 2016-12-16 01:14:38 +02:00
crypto crypto: support HMAC algorithms based on nettle 2016-12-22 09:24:59 +00:00
default-configs nios2: Add support for Nios-II R1 2017-01-24 13:10:36 -08:00
disas nios2 target support 2017-01-25 13:30:23 +00:00
docs docs: sync pci-ids.txt 2017-01-24 23:26:53 +03:00
dtc@65cc4d2748
fpu target-hppa: Add softfloat specializations 2017-01-23 09:52:40 -08:00
fsdev 9pfs: add cleanup operation in FileOperations 2016-11-23 13:53:34 +01:00
gdb-xml
hw This pull request fixes a 2.9 regression and a long standing bug that can 2017-01-25 17:54:14 +00:00
include nios2 target support 2017-01-25 13:30:23 +00:00
io io: introduce a DNS resolver API 2017-01-23 15:32:46 +00:00
libdecnumber
linux-headers vhost: drop VHOST_F_DEVICE_IOTLB 2017-01-18 22:59:54 +02:00
linux-user nios2: Add usermode binaries emulation 2017-01-24 13:10:35 -08:00
migration migration/tracing: Add tracing on save 2017-01-24 18:00:32 +00:00
nbd io: change the QIOTask callback signature 2017-01-23 15:32:18 +00:00
net -----BEGIN PGP SIGNATURE----- 2017-01-20 14:56:40 +00:00
pc-bios Update OpenBIOS images to ef8a14e built from submodule. 2016-11-24 21:26:00 +00:00
pixman@87eea99e44
po po: add missing translations in de, fr, it, zh 2016-12-14 18:47:19 +00:00
qapi qmp-events: move 'MIGRATION_PASS' doc to schema 2017-01-16 09:19:50 +01:00
qga qga: fix erroneous argument to strerror 2017-01-24 23:26:53 +03:00
qobject qdict: implement a qdict_crumple method for un-flattening a dict 2016-10-25 17:56:14 +02:00
qom object: make some funcs static 2017-01-24 23:26:53 +03:00
replay record/replay: add network support 2017-01-06 10:38:00 +08:00
roms Update OpenBIOS images to ef8a14e built from submodule. 2016-11-24 21:26:00 +00:00
scripts * QOM interface fix (Eduardo) 2017-01-20 16:42:07 +00:00
slirp slirp: support dynamic block size for TFTP transfers 2016-12-21 00:02:15 +01:00
stubs migration: disallow migrate_add_blocker during migration 2017-01-24 18:00:30 +00:00
target target/xtensa updates: 2017-01-25 16:36:57 +00:00
tcg tcg/i386: Always use TZCNT when available 2017-01-17 12:02:08 -08:00
tests This pull request fixes a 2.9 regression and a long standing bug that can 2017-01-25 17:54:14 +00:00
trace trace: Add event "guest_cpu_exit" 2017-01-16 13:40:56 +00:00
ui io: change the QIOTask callback signature 2017-01-23 15:32:18 +00:00
util win32: use glib gpoll if glib >= 2.50 2017-01-24 23:26:53 +03:00
.dir-locals.el
.exrc
.gitignore build-sys: add qapi doc generation targets 2017-01-16 10:11:43 +01:00
.gitmodules ppc: add skiboot firmware for the pnv platform 2016-10-28 09:36:58 +11:00
.mailmap
.travis.yml travis: add Trusty with clang stable build 2017-01-12 10:04:17 +00:00
accel.c clean-up: removed duplicate #includes 2016-10-28 18:17:24 +03:00
aio-posix.c aio-posix: honor is_external in AioContext polling 2017-01-26 10:02:33 +00:00
aio-win32.c aio-win32: remove walking_handlers, protecting AioHandler list with list_lock 2017-01-16 13:25:18 +00:00
arch_init.c nios2: Add support for Nios-II R1 2017-01-24 13:10:36 -08:00
async.c async: optimize aio_bh_poll 2017-01-16 13:25:18 +00:00
atomic_template.h tcg: Add atomic128 helpers 2016-10-26 08:29:01 -07:00
balloon.c
block.c block: remove dead check 2017-01-24 23:26:53 +03:00
blockdev-nbd.c nbd: set name for all I/O channels created 2016-10-27 09:13:10 +02:00
blockdev.c blockjob: refactor backup_start as backup_job_create 2016-11-14 22:47:34 -05:00
blockjob.c blockjob: add block_job_start 2016-11-14 22:47:34 -05:00
bootdevice.c
bt-host.c
bt-vhci.c
Changelog
CODING_STYLE CODING_STYLE: Fix a typo ("have" vs. "has") 2016-10-08 11:25:29 +03:00
configure nios2: Add support for Nios-II R1 2017-01-24 13:10:36 -08:00
COPYING
COPYING.LIB
cpu-exec-common.c tcg: Add EXCP_ATOMIC 2016-10-26 08:29:00 -07:00
cpu-exec.c log: Add locking to large logging blocks 2016-11-01 10:29:03 -06:00
cpus-common.c *_run_on_cpu: introduce run_on_cpu_data type 2016-10-31 15:00:25 +01:00
cpus.c Plumb the HAXM-based hardware acceleration support 2017-01-19 22:07:46 +01:00
cputlb.c cputlb: drop flush_global flag from tlb_flush 2017-01-13 14:24:37 +00:00
device_tree.c
device-hotplug.c
disas.c Revert "Remove remainders of HPPA backend" 2017-01-22 18:13:56 -08:00
dma-helpers.c dma-helpers: explicitly pass alignment into DMA helpers 2016-10-27 16:29:13 -04:00
dump.c
exec.c * QOM interface fix (Eduardo) 2017-01-20 16:42:07 +00:00
gdbstub.c gdbstub.c: update old error report statements 2017-01-24 23:26:54 +03:00
HACKING HACKING: document #include order 2017-01-03 16:38:47 +00:00
hax-stub.c Plumb the HAXM-based hardware acceleration support 2017-01-19 22:07:46 +01:00
hmp-commands-info.hx intc: make HMP 'info irq' and 'info pic' commands available on all targets 2016-10-04 10:00:25 +02:00
hmp-commands.hx COLO: Add 'x-colo-lost-heartbeat' command to trigger failover 2016-10-30 15:17:39 +05:30
hmp.c monitor: fix qmp/hmp query-memdev not reporting IDs of memory backends 2017-01-12 15:35:06 -02:00
hmp.h COLO: Add 'x-colo-lost-heartbeat' command to trigger failover 2016-10-30 15:17:39 +05:30
iohandler.c event_notifier: cleanups around event_notifier_set_handler 2017-01-16 17:52:35 +01:00
ioport.c
iothread.c iothread: add poll-grow and poll-shrink parameters 2017-01-03 16:38:50 +00:00
kvm-all.c *_run_on_cpu: introduce run_on_cpu_data type 2016-10-31 15:00:25 +01:00
kvm-stub.c kvm-all: Pass requester ID to MSI routing functions 2016-10-04 13:28:09 +01:00
LICENSE
main-loop.c main-loop: Suppress I/O thread warning under qtest 2016-11-02 09:28:57 +01:00
MAINTAINERS nios2 target support 2017-01-25 13:30:23 +00:00
Makefile Makefile: Add qemu-doc.txt to distclean and dependencies 2017-01-24 14:32:05 +00:00
Makefile.objs virtio, vhost, pc: fixes 2017-01-09 15:30:45 +00:00
Makefile.target Plumb the HAXM-based hardware acceleration support 2017-01-19 22:07:46 +01:00
memory_ldst.inc.c exec: introduce memory_ldst.inc.c 2016-12-22 16:00:23 +01:00
memory_mapping.c memory: Replace skip_dump flag with "ram_device" 2016-10-31 09:53:03 -06:00
memory.c memory: handle alias for iommu notifier 2017-01-10 05:56:59 +02:00
module-common.c
monitor.c * QOM interface fix (Eduardo) 2017-01-20 16:42:07 +00:00
numa.c ramblock-notifier: new 2017-01-16 17:52:35 +01:00
os-posix.c use g_path_get_dirname instead of dirname 2016-07-17 09:59:21 +02:00
os-win32.c
page_cache.c coccinelle: Remove unnecessary variables for function return value 2016-06-20 16:38:13 +02:00
qapi-schema.json sockets: add ability to disable DNS resolution for InetSocketAddress 2017-01-23 15:32:17 +00:00
qdev-monitor.c migration: Allow "device add" options to only add migratable devices 2017-01-24 17:54:47 +00:00
qdict-test-data.txt
qemu-bridge-helper.c
qemu-char.c io: change the QIOTask callback signature 2017-01-23 15:32:18 +00:00
qemu-doc.texi nios2 target support 2017-01-25 13:30:23 +00:00
qemu-ga.texi qemu-ga: Remove stray 'q' in documentation 2016-10-28 18:17:23 +03:00
qemu-img-cmds.hx qemu-img: add skip option to dd 2016-09-20 22:10:57 +02:00
qemu-img.c qemu-img: remove dead check 2017-01-24 23:26:53 +03:00
qemu-img.texi qemu-img: add skip option to dd 2016-09-20 22:10:57 +02:00
qemu-io-cmds.c trivial patches for 2016-10-28 2016-10-31 11:58:30 +00:00
qemu-io.c trace: provide mechanism for registering trace events 2016-10-12 09:52:50 +02:00
qemu-nbd.c nbd: Add qemu-nbd -D for human-readable description 2016-11-02 09:28:55 +01:00
qemu-nbd.texi nbd: Add qemu-nbd -D for human-readable description 2016-11-02 09:28:55 +01:00
qemu-option-trace.texi doc: move text describing --trace to specific .texi file 2016-06-28 21:14:12 +01:00
qemu-options-wrapper.h hxtool: emit Texinfo headings as @subsection 2017-01-16 17:52:35 +01:00
qemu-options.h Clean up ill-advised or unusual header guards 2016-07-12 16:20:46 +02:00
qemu-options.hx trivial patches for 2017-01-24 2017-01-25 10:42:26 +00:00
qemu-seccomp.c seccomp: adding getrusage to the whitelist 2016-09-21 11:26:02 +02:00
qemu-tech.texi qemu-doc: merge qemu-tech and qemu-doc 2016-10-07 10:05:54 +02:00
qemu-timer.c qemu-timer: check active_timers outside lock/event 2016-12-22 16:00:24 +01:00
qemu.nsi qemu-doc: merge qemu-tech and qemu-doc 2016-10-07 10:05:54 +02:00
qemu.sasl
qmp.c clean-up: removed duplicate #includes 2016-10-28 18:17:24 +03:00
qtest.c libqtest: handle zero length memwrite/memread 2017-01-12 10:45:59 +00:00
README README: Add linux to macOS build info 2017-01-24 23:26:52 +03:00
replication.c replication: Introduce new APIs to do replication operation 2016-09-13 11:00:56 +01:00
replication.h replication: Introduce new APIs to do replication operation 2016-09-13 11:00:56 +01:00
rules.mak build-sys: add qapi doc generation targets 2017-01-16 10:11:43 +01:00
softmmu_template.h cputlb: Tidy some macros 2016-10-26 08:29:00 -07:00
spice-qemu-char.c char: remove explicit_be_open from CharDriverState 2016-10-24 15:46:11 +02:00
tcg-runtime.c tcg: Add opcode for ctpop 2017-01-10 08:48:56 -08:00
tci.c tcg/tci: Add support for fence 2016-09-16 08:12:12 -07:00
thread-pool.c coroutine: move entry argument to qemu_coroutine_create 2016-07-13 13:26:02 +02:00
thunk.c
tpm.c
trace-events trace: Add event "guest_cpu_exit" 2017-01-16 13:40:56 +00:00
translate-all.c translate-all: Avoid -Werror=switch-bool 2017-01-08 09:48:34 -08:00
translate-all.h trace: Add per-vCPU tracing states for events with the 'vcpu' property 2016-07-18 18:23:12 +01:00
translate-common.c
user-exec-stub.c stubs: group stubs for user-mode emulation 2017-01-16 17:52:35 +01:00
user-exec.c tcg: Merge GETPC and GETRA 2016-09-16 08:12:11 -07:00
VERSION Open 2.9 development tree 2016-12-20 16:20:16 +00:00
version.rc
vl.c migration: Add a new option to enable only-migratable 2017-01-24 17:54:47 +00:00
xen-common-stub.c
xen-common.c xen: Fix xenpv machine initialisation 2016-11-08 11:17:30 -08:00
xen-hvm-stub.c
xen-hvm.c xen: ignore direction in bufioreq handling 2016-11-28 11:26:29 -08:00
xen-mapcache.c ramblock-notifier: new 2017-01-16 17:52:35 +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:

  http://qemu-project.org/Hosts/Linux
  http://qemu-project.org/Hosts/Mac
  http://qemu-project.org/Hosts/W32


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

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

   git clone git://git.qemu-project.org/qemu.git

When submitting patches, the preferred 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

  http://qemu-project.org/Contribute/SubmitAPatch
  http://qemu-project.org/Contribute/TrivialPatches


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:

  http://qemu-project.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
   http://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:

  http://qemu-project.org/Contribute/StartHere

-- End