Re: [Qemu-devel] migration: qemu-coroutine-lock.c:141: qemu_co_mutex_unlock: Assertion `mutex->locked == 1' failed

[Paolo Bonzini <pbonzini@redhat.com>]

Il 16/09/2014 14:02, Alexey Kardashevskiy ha scritto:
> I am having problems when migrate a guest via libvirt like this:
> 
> virsh migrate --live --persistent --undefinesource --copy-storage-all
> --verbose --desturi qemu+ssh://legkvm/system --domain chig1
> 
> The XML used to create the guest is at the end of this mail.
> 
> I see NBD FLUSH command after the destination QEMU received EOF for
> migration stream and this produces a crash in qcow2_co_flush_to_os() as
> s->lock is false or s->l2_table_cache is NULL.
> 

Max, Kevin, could the fix be something like this?

diff --git a/block/qcow2.c b/block/qcow2.c
index 0daf25c..e7459ea 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1442,6 +1442,7 @@ static void qcow2_invalidate_cache(BlockDriverState *bs, Error **errp)
         memcpy(&aes_decrypt_key, &s->aes_decrypt_key, sizeof(aes_decrypt_key));
     }
 
+    qemu_co_mutex_lock(&s->lock);
     qcow2_close(bs);
 
     bdrv_invalidate_cache(bs->file, &local_err);
@@ -1455,6 +1456,7 @@ static void qcow2_invalidate_cache(BlockDriverState *bs, Error **errp)
 
     ret = qcow2_open(bs, options, flags, &local_err);
     QDECREF(options);
+    qemu_co_mutex_unlock(&s->lock);
     if (local_err) {
         error_setg(errp, "Could not reopen qcow2 layer: %s",
                    error_get_pretty(local_err));

On top of this, *_invalidate_cache needs to be marked as coroutine_fn.

Paolo