Am 13.09.2018 um 17:10 hat Paolo Bonzini geschrieben: > On 13/09/2018 14:52, Kevin Wolf wrote: > > + if (qemu_get_current_aio_context() == qemu_get_aio_context()) { > > + /* If we are in the main thread, the callback is allowed to unref > > + * the BlockBackend, so we have to hold an additional reference */ > > + blk_ref(acb->rwco.blk); > > + } > > acb->common.cb(acb->common.opaque, acb->rwco.ret); > > + blk_dec_in_flight(acb->rwco.blk); > > + if (qemu_get_current_aio_context() == qemu_get_aio_context()) { > > + blk_unref(acb->rwco.blk); > > + } > > Is this something that happens only for some specific callers? That is, > which callers are sure that the callback is invoked from the main thread?
I can't seem to reproduce the problem I saw any more even when reverting the bdrv_ref/unref pair. If I remember correctly it was actually a nested aio_poll() that was running a block job completion or something like that - which would obviously only happen on the main thread because the job intentionally defers to the main thread. The only reason I made this conditional is that I think bdrv_unref() still isn't safe outside the main thread, is it? Kevin