AW: [PATCH v2 05/12] kern_tc.c: Replace FREEBSD event mechanism by adding pointers to function

[Gabriel.Moyano at dlr.de]

> On 29/04/2022 09:20, Gabriel Moyano wrote:
> > ---
> >   cpukit/include/sys/timepps.h |  6 ++++++
> >   cpukit/score/src/kern_tc.c   | 25 +++++++++++++++++++++++++
> >   2 files changed, 31 insertions(+)
> >
> > diff --git a/cpukit/include/sys/timepps.h
> > b/cpukit/include/sys/timepps.h index 5703381ffa..0d666a4f2e 100644
> > --- a/cpukit/include/sys/timepps.h
> > +++ b/cpukit/include/sys/timepps.h
> > @@ -26,6 +26,7 @@
> >   #include <sys/time.h>
> >   #ifdef __rtems__
> >   #include <rtems/score/atomic.h>
> > +#include <rtems/rtems/types.h>
> >   #endif /* __rtems__ */
> >
> >   #define PPS_API_VERS_1	1
> > @@ -164,6 +165,11 @@ struct pps_state {
> >   	int		ppscap;
> >   	struct timecounter *ppstc;
> >   	unsigned	ppscount[3];
> > +#ifdef __rtems__
> > +    rtems_id task_waiting;
> 
> You don't need task_waiting, this is an implementation detail of potential wait/wakeup implementations.

What do you think here of replacing it with a void* because some variable is required to save the tasks waiting

> > +    int (*wait)(struct pps_state *pps, struct timespec timeout); /* Wait for an event. Called internally when time_pps_fetch() is
> used. It shall not be NULL*/
> > +    void (*wakeup)(struct pps_state *pps); /* Used to wakeup tasks
> > + waiting for an event. It shall not be NULL*/
> 
> Please fix the formatting and take care that you keep the line limit.
> 
> > +#endif /* __rtems__ */
> >   	/*
> >   	 * The following fields are valid if the driver calls pps_init_abi().
> >   	 */
> > diff --git a/cpukit/score/src/kern_tc.c b/cpukit/score/src/kern_tc.c
> > index f7d0a0b4ba..76e3e056de 100644
> > --- a/cpukit/score/src/kern_tc.c
> > +++ b/cpukit/score/src/kern_tc.c
> > @@ -1917,9 +1917,15 @@ abi_aware(struct pps_state *pps, int vers)
> >   static int
> >   pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps)
> >   {
> > +#ifndef __rtems__
> >   	int err, timo;
> > +#else /* __rtems__ */
> > +	int err;
> > +#endif /* __rtems__ */
> >   	pps_seq_t aseq, cseq;
> > +#ifndef __rtems__
> >   	struct timeval tv;
> > +#endif /* __rtems__ */
> >
> >   	if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
> >   		return (EINVAL);
> > @@ -1932,6 +1938,7 @@ pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps)
> >   	 * sleep a long time.
> >   	 */
> >   	if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec) {
> > +#ifndef __rtems__
> >   		if (fapi->timeout.tv_sec == -1)
> >   			timo = 0x7fffffff;
> >   		else {
> > @@ -1939,10 +1946,12 @@ pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps)
> >   			tv.tv_usec = fapi->timeout.tv_nsec / 1000;
> >   			timo = tvtohz(&tv);
> >   		}
> > +#endif /* __rtems__ */
> >   		aseq = atomic_load_int(&pps->ppsinfo.assert_sequence);
> >   		cseq = atomic_load_int(&pps->ppsinfo.clear_sequence);
> >   		while (aseq == atomic_load_int(&pps->ppsinfo.assert_sequence) &&
> >   		    cseq == atomic_load_int(&pps->ppsinfo.clear_sequence)) {
> > +#ifndef __rtems__
> >   			if (abi_aware(pps, 1) && pps->driver_mtx != NULL) {
> >   				if (pps->flags & PPSFLAG_MTX_SPIN) {
> >   					err = msleep_spin(pps, pps->driver_mtx, @@ -1954,6 +1963,12 @@
> > pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps)
> >   			} else {
> >   				err = tsleep(pps, PCATCH, "ppsfch", timo);
> >   			}
> > +#else /* __rtems__ */
> > +            if (pps->wait != NULL)
> > +                err = (*pps->wait)(pps, fapi->timeout);
> > +            else
> > +                err = EAGAIN;
> > +#endif /* __rtems__ */
> 
> Replace the NULL check with an _Assert().  Check in pps_init() that the handler are not NULL, otherwise generate a new fatal error.
> You need tests for the fatal errors.

Actually the synchronization can work without these functions; wait() is called in pps_time_fetch() and wakeup() wakes up the waiting task(s). This is also why there is one _Assert() in pps_init() but if you consider better to add other for wait(), it can be done.
 
> >   			if (err == EWOULDBLOCK) {
> >   				if (fapi->timeout.tv_sec == -1) {
> >   					continue;
> > @@ -2061,6 +2076,11 @@ pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
> >   void
> >   pps_init(struct pps_state *pps)
> >   {
> > +#ifdef __rtems__
> > +    if (pps->wait != NULL)
> > +        _Assert(pps->wakeup != NULL);
> > +    pps->task_waiting = RTEMS_INVALID_ID; #endif /* __rtems__ */
> >   	pps->ppscap |= PPS_TSFMT_TSPEC | PPS_CANWAIT;
> >   	if (pps->ppscap & PPS_CAPTUREASSERT)
> >   		pps->ppscap |= PPS_OFFSETASSERT;
> > @@ -2227,7 +2247,12 @@ pps_event(struct pps_state *pps, int event)
> >   #endif
> >
> >   	/* Wakeup anyone sleeping in pps_fetch().  */
> > +#ifndef __rtems__
> >   	wakeup(pps);
> > +#else /* __rtems__ */
> > +    if (pps->wakeup != NULL)
> > +        (*pps->wakeup)(pps);
> > +#endif /* __rtems__ */
> 
> Add an _Assert() and just call pps->wakeup.
> 
> >   }
> >   #else /* __rtems__ */
> >   /* FIXME: https://devel.rtems.org/ticket/2349 */
>