Re: [PATCH 02/10] vfio: ccw: Transform FSM functions to return state

Pierre Morel
2018-04-24T08:22:15Z

On 24/04/2018 09:25, Dong Jia Shi wrote:
> * Pierre Morel <pmorel@linux.vnet.ibm.com> [2018-04-19 16:48:05 +0200]:
>
>> We change the FSM functions to return the next state,
>> and adapt the fsm_func_t function type.
> I think I'd need to read the rest patches to understand why we need this
> one, but no hurt to write some ideas that I noticed at my first glance.
> See below please.
>
>> Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
>> ---
>> drivers/s390/cio/vfio_ccw_fsm.c | 24 ++++++++++++++++--------
>> drivers/s390/cio/vfio_ccw_private.h | 5 +++--
>> 2 files changed, 19 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
>> index af88551..2f3108d 100644
>> --- a/drivers/s390/cio/vfio_ccw_fsm.c
>> +++ b/drivers/s390/cio/vfio_ccw_fsm.c
>> @@ -60,7 +60,7 @@ static int fsm_io_helper(struct vfio_ccw_private *private)
>> }
>> }
>>
>> -static void fsm_notoper(struct vfio_ccw_private *private,
>> +static int fsm_notoper(struct vfio_ccw_private *private,
>> enum vfio_ccw_event event)
>> {
>> struct subchannel *sch = private->sch;
>> @@ -71,30 +71,34 @@ static void fsm_notoper(struct vfio_ccw_private *private,
>> */
>> css_sched_sch_todo(sch, SCH_TODO_UNREG);
>> private->state = VFIO_CCW_STATE_NOT_OPER;
> Here..
>
>> + return private->state;
>> }
>>
>> /*
>> * No operation action.
>> */
>> -static void fsm_nop(struct vfio_ccw_private *private,
>> +static int fsm_nop(struct vfio_ccw_private *private,
>> enum vfio_ccw_event event)
>> {
>> + return private->state;
>> }
>>
>> -static void fsm_io_error(struct vfio_ccw_private *private,
>> +static int fsm_io_error(struct vfio_ccw_private *private,
>> enum vfio_ccw_event event)
>> {
>> pr_err("vfio-ccw: FSM: I/O request from state:%d\n", private->state);
>> private->io_region.ret_code = -EIO;
>> + return private->state;
>> }
>>
>> -static void fsm_io_busy(struct vfio_ccw_private *private,
>> +static int fsm_io_busy(struct vfio_ccw_private *private,
>> enum vfio_ccw_event event)
>> {
>> private->io_region.ret_code = -EBUSY;
>> + return private->state;
>> }
>>
>> -static void fsm_disabled_irq(struct vfio_ccw_private *private,
>> +static int fsm_disabled_irq(struct vfio_ccw_private *private,
>> enum vfio_ccw_event event)
>> {
>> struct subchannel *sch = private->sch;
>> @@ -104,12 +108,13 @@ static void fsm_disabled_irq(struct vfio_ccw_private *private,
>> * successful - should not happen, but we try to disable again.
>> */
>> cio_disable_subchannel(sch);
>> + return private->state;
>> }
>>
>> /*
>> * Deal with the ccw command request from the userspace.
>> */
>> -static void fsm_io_request(struct vfio_ccw_private *private,
>> +static int fsm_io_request(struct vfio_ccw_private *private,
>> enum vfio_ccw_event event)
>> {
>> union orb *orb;
>> @@ -141,7 +146,7 @@ static void fsm_io_request(struct vfio_ccw_private *private,
>> cp_free(&private->cp);
>> goto err_out;
>> }
>> - return;
>> + return private->state;
>> } else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {
>> /* XXX: Handle halt. */
>> io_region->ret_code = -EOPNOTSUPP;
>> @@ -154,12 +159,13 @@ static void fsm_io_request(struct vfio_ccw_private *private,
>>
>> err_out:
>> private->state = VFIO_CCW_STATE_IDLE;
> Here..
>
>> + return private->state;
>> }
>>
>> /*
>> * Got an interrupt for a normal io (state busy).
>> */
>> -static void fsm_irq(struct vfio_ccw_private *private,
>> +static int fsm_irq(struct vfio_ccw_private *private,
>> enum vfio_ccw_event event)
>> {
>> struct irb *irb = &private->irb;
>> @@ -172,6 +178,8 @@ static void fsm_irq(struct vfio_ccw_private *private,
>>
>> if (private->io_trigger)
>> eventfd_signal(private->io_trigger, 1);
>> +
>> + return private->state;
>> }
>>
>> /*
>> diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
>> index 78a66d9..f526b18 100644
>> --- a/drivers/s390/cio/vfio_ccw_private.h
>> +++ b/drivers/s390/cio/vfio_ccw_private.h
>> @@ -83,13 +83,14 @@ enum vfio_ccw_event {
>> /*
>> * Action called through jumptable.
>> */
>> -typedef void (fsm_func_t)(struct vfio_ccw_private *, enum vfio_ccw_event);
>> +typedef int (fsm_func_t)(struct vfio_ccw_private *, enum vfio_ccw_event);
>> extern fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS];
>>
>> static inline void vfio_ccw_fsm_event(struct vfio_ccw_private *private,
>> int event)
>> {
>> - vfio_ccw_jumptable[private->state][event](private, event);
>> + private->state = vfio_ccw_jumptable[private->state][event](private,
>> + event);
> Since here it assigns new value to private->state, there is no need to
> do that inside each fsm_func?
Absolutely.
I just kept the previous code, just adding the return private->state in
the functions
in this patch.
merging the state and the return value is done in a later patch.
If you prefer I can do it in this patch.

>
>> }
>>
>> extern struct workqueue_struct *vfio_ccw_work_q;
>> --
>> 2.7.4
>>

--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany