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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>
This commit is contained in:
Fam Zheng 2016-09-08 17:28:51 +08:00 committed by Stefan Hajnoczi
parent e49f827725
commit dce8921b2b
3 changed files with 23 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/sysemu/iothread.h
View File

@ -35,5 +35,6 @@ typedef struct {
char *iothread_get_id(IOThread *iothread);
AioContext *iothread_get_aio_context(IOThread *iothread);
void iothread_stop_all(void);
#endif /* IOTHREAD_H */

24
iothread.c
View File

@ -54,16 +54,25 @@ static void *iothread_run(void *opaque)
return NULL;
}
static void iothread_instance_finalize(Object *obj)
static int iothread_stop(Object *object, void *opaque)
{
IOThread *iothread = IOTHREAD(obj);
IOThread *iothread;
if (!iothread->ctx) {
return;
iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
if (!iothread || !iothread->ctx) {
return 0;
}
iothread->stopping = true;
aio_notify(iothread->ctx);
qemu_thread_join(&iothread->thread);
return 0;
}
static void iothread_instance_finalize(Object *obj)
{
IOThread *iothread = IOTHREAD(obj);
iothread_stop(obj, NULL);
qemu_cond_destroy(&iothread->init_done_cond);
qemu_mutex_destroy(&iothread->init_done_lock);
aio_context_unref(iothread->ctx);
@ -174,3 +183,10 @@ IOThreadInfoList *qmp_query_iothreads(Error **errp)
object_child_foreach(container, query_one_iothread, &prev);
return head;
}
void iothread_stop_all(void)
{
Object *container = object_get_objects_root();
object_child_foreach(container, iothread_stop, NULL);
}

2
vl.c
View File

@ -121,6 +121,7 @@ int main(int argc, char **argv)
#include "crypto/init.h"
#include "sysemu/replay.h"
#include "qapi/qmp/qerror.h"
#include "sysemu/iothread.h"
#define MAX_VIRTIO_CONSOLES 1
#define MAX_SCLP_CONSOLES 1
@ -4616,6 +4617,7 @@ int main(int argc, char **argv, char **envp)
trace_init_vcpu_events();
main_loop();
replay_disable_events();
iothread_stop_all();
bdrv_close_all();
pause_all_vcpus();