there is a possibility of calling bdrv_co_io_em_complete before calling qemu_coroutine_yield in bdrv_co_io_em. And qemu fails with "co-routine re-entered recursively".
static void bdrv_co_io_em_complete(void *opaque, int ret)
{
CoroutineIOCompletion *co = opaque;
co->ret = ret;
qemu_coroutine_enter(co->coroutine, NULL);
}
static int coroutine_fn bdrv_co_io_em(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *iov,
bool is_write)
{
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
BlockDriverAIOCB *acb;
if (is_write) {
acb = bs->drv->bdrv_aio_writev(bs, sector_num, iov, nb_sectors,
bdrv_co_io_em_complete, &co);
} else {
acb = bs->drv->bdrv_aio_readv(bs, sector_num, iov, nb_sectors,
bdrv_co_io_em_complete, &co);
}
trace_bdrv_co_io_em(bs, sector_num, nb_sectors, is_write, acb);
if (!acb) {
return -EIO;
}
qemu_coroutine_yield();
return co.ret;
}