The goal of the patch serie is to enhance the state machine by: - centralizing all state changes inside the state machine wrapper - make the state change atomic using mutexes - change user busy waiting for a passive wait on completion - refactoring the initialization to avoid using a subchannel without a guest This series introduces new states and events and suppressed others. - VFIO_CCW_STATE_NOT_OPER : when the Sub-Channel is KO - VFIO_CCW_STATE_STANDBY : when it is offline - VFIO_CCW_STATE_IDLE : when it is ready for I/O - VFIO_CCW_STATE_BUSY : when it is busy doing I/O - VFIO_CCW_STATE_QUIESCING: when it is busy going offline - VFIO_CCW_EVENT_INIT : the channel setup (admin) - VFIO_CCW_EVENT_NOT_OPER : something really wrong happened - VFIO_CCW_EVENT_SSCH_REQ : Starting an I/O request (UAPI) - VFIO_CCW_EVENT_INTERRUPT: Receiving an interrupt (callback) - VFIO_CCW_EVENT_SCHIB_CHANGED: Receiving a channel event (callback) - VFIO_CCW_EVENT_ONLINE : Channel is set online (admin) - VFIO_CCW_EVENT_OFFLINE : Channel is set offline (admin) The ABI did not change a lot beside letting the user sleep when the driver is busy doing a SSCH, so a standard QEMU devel branch can be used. Pierre Morel (10): vfio: ccw: Moving state change out of IRQ context vfio: ccw: Transform FSM functions to return state vfio: ccw: new SCH_EVENT event vfio: ccw: replace IO_REQ event with SSCH_REQ event vfio: ccw: Suppress unused event parameter vfio: ccw: Make FSM functions atomic vfio: ccw: FSM and mediated device initialization vfio: ccw: Handling reset and shutdown with states vfio: ccw: Suppressing the BOXED state vfio: ccw: Let user wait when busy on IO drivers/s390/cio/vfio_ccw_drv.c | 112 +++++------------- drivers/s390/cio/vfio_ccw_fsm.c | 218 ++++++++++++++++++++++++------------ drivers/s390/cio/vfio_ccw_ops.c | 62 +++++----- drivers/s390/cio/vfio_ccw_private.h | 18 ++- 4 files changed, 219 insertions(+), 191 deletions(-) -- 2.7.4 Changelog: - rebased on current Linux branch - change the name of VFIO_CCW_EVENT_SCH_EVENT to VFIO_CCW_EVENT_SCHIB_CHANGED - refactoring the initialization (mdev create/open and driver probe) - return -EAGAIN to let the low level retry the sending of events - make wait_for_completion interruptible