Hi,
We are currently experiencing this bug reported by Sebastian Huber and I
could not find any discussion on it on the list. I'm guessing that the
simple solution of moving the call to Clock_driver_support_at_tick() to
the critical section of _TOD_Tickle_ticks() is not an acceptable
solution, given that it would be a call from score to the BSP?
Best regards,
Daniel C
On 2014-06-05 15:29, bugzilla-dae...@rtems.org wrote:
https://www.rtems.org/bugzilla/show_bug.cgi?id=2180
Bug #: 2180
Summary: _TOD_Get_with_nanoseconds() is broken on SMP
Classification: Unclassified
Product: RTEMS
Version: 4.11
Platform: All
OS/Version: RTEMS
Status: NEW
Severity: normal
Priority: P3
Component: cpukit
AssignedTo: joel.sherr...@oarcorp.com
ReportedBy: sebastian.hu...@embedded-brains.de
We have
Timestamp_Control *_TOD_Get_with_nanoseconds(
Timestamp_Control *snapshot,
const Timestamp_Control *clock
)
{
TOD_Control *tod = &_TOD;
ISR_lock_Context lock_context;
Timestamp_Control offset;
Timestamp_Control now;
uint32_t nanoseconds;
_TOD_Acquire( tod, &lock_context );
nanoseconds = ( *tod->nanoseconds_since_last_tick )();
now = *clock;
_TOD_Release( tod, &lock_context );
_Timestamp_Set( &offset, 0, nanoseconds );
_Timestamp_Add_to( &now, &offset );
*snapshot = now;
return snapshot;
}
and
void _TOD_Tickle_ticks( void )
{
TOD_Control *tod = &_TOD;
ISR_lock_Context lock_context;
Timestamp_Control tick;
uint32_t nanoseconds_per_tick;
nanoseconds_per_tick = rtems_configuration_get_nanoseconds_per_tick();
/* Convert the tick quantum to a timestamp */
_Timestamp_Set( &tick, 0, nanoseconds_per_tick );
/* Update the counter of ticks since boot */
_Watchdog_Ticks_since_boot += 1;
_TOD_Acquire( tod, &lock_context );
/* Update the uptime */
_Timestamp_Add_to( &tod->uptime, &tick );
/* Update the current TOD */
_Timestamp_Add_to( &tod->now, &tick );
_TOD_Release( tod, &lock_context );
_TOD.seconds_trigger += nanoseconds_per_tick;
if ( _TOD.seconds_trigger >= 1000000000UL ) {
_TOD.seconds_trigger -= 1000000000UL;
_Watchdog_Tickle_seconds();
}
}
and (standard Clock driver)
#if defined(BSP_FEATURE_IRQ_EXTENSION) || \
(CPU_SIMPLE_VECTORED_INTERRUPTS != TRUE)
void Clock_isr(void *arg)
{
#else
rtems_isr Clock_isr(rtems_vector_number vector);
rtems_isr Clock_isr(
rtems_vector_number vector
)
{
#endif
/*
* Accurate count of ISRs
*/
Clock_driver_ticks += 1;
#if CLOCK_DRIVER_USE_FAST_IDLE
do {
rtems_clock_tick();
} while (
_Thread_Heir == _Thread_Executing
&& _Thread_Executing->Start.entry_point
== rtems_configuration_get_idle_task()
);
Clock_driver_support_at_tick();
return;
#else
/*
* Do the hardware specific per-tick action.
*
* The counter/timer may or may not be set to automatically reload.
*/
Clock_driver_support_at_tick();
#if CLOCK_DRIVER_ISRS_PER_TICK
/*
* The driver is multiple ISRs per clock tick.
*/
if ( !Clock_driver_isrs ) {
rtems_clock_tick();
Clock_driver_isrs = CLOCK_DRIVER_ISRS_PER_TICK;
}
Clock_driver_isrs--;
#else
/*
* The driver is one ISR per clock tick.
*/
rtems_clock_tick();
#endif
#endif
}
Suppose we are between Clock_driver_support_at_tick() and _TOD_Tickle_ticks().
Now call _TOD_Get_with_nanoseconds() on another processor. With most
nanoseconds extensions we observe now a serviced hardware clock interrupt and
the old _TOD.uptime value.
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