qemu/include/sysemu/iothread.h
Fam Zheng dce8921b2b iothread: Stop threads before main() quits
Right after main_loop ends, we release various things but keep iothread
alive. The latter is not prepared to the sudden change of resources.

Specifically, after bdrv_close_all(), virtio-scsi dataplane get a
surprise at the empty BlockBackend:

(gdb) bt
    at /usr/src/debug/qemu-2.6.0/hw/scsi/virtio-scsi.c:543
    at /usr/src/debug/qemu-2.6.0/hw/scsi/virtio-scsi.c:577

It is because the d->conf.blk->root is set to NULL, then
blk_get_aio_context() returns qemu_aio_context, whereas s->ctx is still
pointing to the iothread:

    hw/scsi/virtio-scsi.c:543:

    if (s->dataplane_started) {
        assert(blk_get_aio_context(d->conf.blk) == s->ctx);
    }

To fix this, let's stop iothreads before doing bdrv_close_all().

Cc: qemu-stable@nongnu.org
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1473326931-9699-1-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-09-13 11:00:57 +01:00

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/*
* Event loop thread
*
* Copyright Red Hat Inc., 2013
*
* Authors:
* Stefan Hajnoczi <stefanha@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#ifndef IOTHREAD_H
#define IOTHREAD_H
#include "block/aio.h"
#include "qemu/thread.h"
#define TYPE_IOTHREAD "iothread"
typedef struct {
Object parent_obj;
QemuThread thread;
AioContext *ctx;
QemuMutex init_done_lock;
QemuCond init_done_cond; /* is thread initialization done? */
bool stopping;
int thread_id;
} IOThread;
#define IOTHREAD(obj) \
OBJECT_CHECK(IOThread, obj, TYPE_IOTHREAD)
char *iothread_get_id(IOThread *iothread);
AioContext *iothread_get_aio_context(IOThread *iothread);
void iothread_stop_all(void);
#endif /* IOTHREAD_H */