59c9f437c5
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> |
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audio | ||
backends | ||
block | ||
bsd-user | ||
contrib | ||
crypto | ||
default-configs | ||
disas | ||
docs | ||
dtc@65cc4d2748 | ||
fpu | ||
fsdev | ||
gdb-xml | ||
hw | ||
include | ||
io | ||
libdecnumber | ||
linux-headers | ||
linux-user | ||
migration | ||
nbd | ||
net | ||
pc-bios | ||
pixman@87eea99e44 | ||
po | ||
qapi | ||
qga | ||
qobject | ||
qom | ||
replay | ||
roms | ||
scripts | ||
slirp | ||
stubs | ||
target | ||
tcg | ||
tests | ||
trace | ||
ui | ||
util | ||
.dir-locals.el | ||
.exrc | ||
.gitignore | ||
.gitmodules | ||
.mailmap | ||
.travis.yml | ||
accel.c | ||
aio-posix.c | ||
aio-win32.c | ||
arch_init.c | ||
async.c | ||
atomic_template.h | ||
balloon.c | ||
block.c | ||
blockdev-nbd.c | ||
blockdev.c | ||
blockjob.c | ||
bootdevice.c | ||
bt-host.c | ||
bt-vhci.c | ||
Changelog | ||
CODING_STYLE | ||
configure | ||
COPYING | ||
COPYING.LIB | ||
cpu-exec-common.c | ||
cpu-exec.c | ||
cpus-common.c | ||
cpus.c | ||
cputlb.c | ||
device_tree.c | ||
device-hotplug.c | ||
disas.c | ||
dma-helpers.c | ||
dump.c | ||
exec.c | ||
gdbstub.c | ||
HACKING | ||
hax-stub.c | ||
hmp-commands-info.hx | ||
hmp-commands.hx | ||
hmp.c | ||
hmp.h | ||
iohandler.c | ||
ioport.c | ||
iothread.c | ||
kvm-all.c | ||
kvm-stub.c | ||
LICENSE | ||
main-loop.c | ||
MAINTAINERS | ||
Makefile | ||
Makefile.objs | ||
Makefile.target | ||
memory_ldst.inc.c | ||
memory_mapping.c | ||
memory.c | ||
module-common.c | ||
monitor.c | ||
numa.c | ||
os-posix.c | ||
os-win32.c | ||
page_cache.c | ||
qapi-schema.json | ||
qdev-monitor.c | ||
qdict-test-data.txt | ||
qemu-bridge-helper.c | ||
qemu-char.c | ||
qemu-doc.texi | ||
qemu-ga.texi | ||
qemu-img-cmds.hx | ||
qemu-img.c | ||
qemu-img.texi | ||
qemu-io-cmds.c | ||
qemu-io.c | ||
qemu-nbd.c | ||
qemu-nbd.texi | ||
qemu-option-trace.texi | ||
qemu-options-wrapper.h | ||
qemu-options.h | ||
qemu-options.hx | ||
qemu-seccomp.c | ||
qemu-tech.texi | ||
qemu-timer.c | ||
qemu.nsi | ||
qemu.sasl | ||
qmp.c | ||
qtest.c | ||
README | ||
replication.c | ||
replication.h | ||
rules.mak | ||
softmmu_template.h | ||
spice-qemu-char.c | ||
tcg-runtime.c | ||
tci.c | ||
thread-pool.c | ||
thunk.c | ||
tpm.c | ||
trace-events | ||
translate-all.c | ||
translate-all.h | ||
translate-common.c | ||
user-exec-stub.c | ||
user-exec.c | ||
VERSION | ||
version.rc | ||
vl.c | ||
xen-common-stub.c | ||
xen-common.c | ||
xen-hvm-stub.c | ||
xen-hvm.c | ||
xen-mapcache.c |
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