On 18/02/19 17:18, Kevin Wolf wrote: > + /* aio_ctx_switch is only supposed to be set if we're sitting in > + * the qio_channel_yield() below. */ > + assert(!*aio_ctx_switch); > bdrv_dec_in_flight(bs); > qio_channel_yield(ioc, G_IO_IN); > - bdrv_inc_in_flight(bs); > + if (*aio_ctx_switch) { > + /* nbd_client_attach_aio_context() already increased > in_flight > + * when scheduling this coroutine for reentry */ > + *aio_ctx_switch = false; > + } else { > + bdrv_inc_in_flight(bs); > + }
Hmm, my first thought would have been to do the bdrv_inc_in_flight(bs); unconditionally here, and in nbd_connection_entry do the opposite, like if (s->aio_ctx_switch) { s->aio_ctx_switch = false; bdrv_dec_in_flight(bs); } but I guess the problem is that then bdrv_drain could hang. So my question is: 1) is there a testcase that shows the problem with this "obvious" refactoring; 2) maybe instead of aio_co_schedul-ing client->connection_co and having the s->aio_ctx_switch flag, you could go through a bottom half that does the bdrv_inc_in_flight and then enters client->connection_co? Paolo