Commit dce8921b authored by Fam Zheng's avatar Fam Zheng Committed by Stefan Hajnoczi
Browse files

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: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1473326931-9699-1-git-send-email-famz@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent e49f8277

include/sysemu/iothread.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

iothread.c

+20 −4
Original line number Diff line number Diff line
@@ -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);

}

vl.c

+2 −0
Original line number Diff line number Diff line
@@ -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();