Some QMP command handlers can block the main loop for a relatively long time, for example because they perform some I/O. This is quite nasty. Allowing such handlers to run in a coroutine where they can yield (and therefore release the BQL) while waiting for an event such as I/O completion solves the problem.
This series adds the infrastructure to allow this and switches block_resize to run in a coroutine as a first example. This is an alternative solution to Marc-André's "monitor: add asynchronous command type" series. v6: - Fixed cur_mon behaviour: It should always point to the Monitor while we're in the handler coroutine, but be NULL while the handler coroutines has yielded. [Markus] - Give HMP handlers the coroutine option, too, because they will call QMP handlers, and life is easier when we know whether we are in coroutine context or not. - Fixed block_resize for block devices in iothreads and for HMP - Resolved some merge conflict with QAPI generator and monitor refactorings that were merged in the meantime v5: - Improved comments and documentation [Markus] v4: - Forbid 'oob': true, 'coroutine': true [Markus] - Removed Python type hints [Markus] - Introduced separate bool qmp_dispatcher_co_shutdown to make it clearer how a shutdown request is signalled to the dispatcher [Markus] - Allow using aio_poll() with iohandler_ctx and use that instead of aio_bh_poll() [Markus] - Removed coroutine_fn from qmp_block_resize() again because at least one caller (HMP) calls it outside of coroutine context [Markus] - Tried to make the synchronisation between dispatcher and the monitor thread clearer, and fixed a race condition - Improved documentation and comments v3: - Fix race between monitor thread and dispatcher that could schedule the dispatcher coroutine twice if a second requests comes in before the dispatcher can wake up [Patchew] v2: - Fix typo in a commit message [Eric] - Use hyphen instead of underscore for the test command [Eric] - Mark qmp_block_resize() as coroutine_fn [Stefan] Kevin Wolf (12): monitor: Add Monitor parameter to monitor_set_cpu() monitor: Use getter/setter functions for cur_mon hmp: Set cur_mon only in handle_hmp_command() qmp: Assert that no other monitor is active qmp: Call monitor_set_cur() only in qmp_dispatch() monitor: Make current monitor a per-coroutine property qapi: Add a 'coroutine' flag for commands qmp: Move dispatcher to a coroutine hmp: Add support for coroutine command handlers util/async: Add aio_co_reschedule_self() block: Add bdrv_co_move_to_aio_context() block: Convert 'block_resize' to coroutine qapi/block-core.json | 3 +- docs/devel/qapi-code-gen.txt | 12 +++ include/block/aio.h | 10 ++ include/block/block.h | 6 ++ include/monitor/monitor.h | 5 +- include/qapi/qmp/dispatch.h | 5 +- monitor/monitor-internal.h | 7 +- audio/wavcapture.c | 8 +- block.c | 10 ++ blockdev.c | 13 ++- dump/dump.c | 2 +- hw/scsi/vhost-scsi.c | 2 +- hw/virtio/vhost-vsock.c | 2 +- migration/fd.c | 4 +- monitor/hmp-cmds.c | 2 +- monitor/hmp.c | 51 +++++++--- monitor/misc.c | 21 ++-- monitor/monitor.c | 87 ++++++++++++++-- monitor/qmp-cmds-control.c | 2 + monitor/qmp-cmds.c | 2 +- monitor/qmp.c | 130 +++++++++++++++++------- net/socket.c | 2 +- net/tap.c | 6 +- qapi/qmp-dispatch.c | 52 +++++++++- qapi/qmp-registry.c | 3 + qga/main.c | 2 +- stubs/monitor-core.c | 9 +- tests/test-qmp-cmds.c | 10 +- tests/test-util-sockets.c | 22 ++-- trace/control.c | 2 +- util/aio-posix.c | 8 +- util/async.c | 30 ++++++ util/qemu-error.c | 4 +- util/qemu-print.c | 3 +- util/qemu-sockets.c | 1 + scripts/qapi/commands.py | 10 +- scripts/qapi/doc.py | 2 +- scripts/qapi/expr.py | 10 +- scripts/qapi/introspect.py | 2 +- scripts/qapi/schema.py | 12 ++- tests/qapi-schema/test-qapi.py | 7 +- hmp-commands.hx | 1 + tests/Makefile.include | 1 + tests/qapi-schema/oob-coroutine.err | 2 + tests/qapi-schema/oob-coroutine.json | 2 + tests/qapi-schema/oob-coroutine.out | 0 tests/qapi-schema/qapi-schema-test.json | 1 + tests/qapi-schema/qapi-schema-test.out | 2 + 48 files changed, 454 insertions(+), 136 deletions(-) create mode 100644 tests/qapi-schema/oob-coroutine.err create mode 100644 tests/qapi-schema/oob-coroutine.json create mode 100644 tests/qapi-schema/oob-coroutine.out -- 2.25.4
