xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

um: time-travel: Rewrite as an event scheduler

Browse Source 
Instead of tracking all the various timer configurations,
modify the time-travel mode to have an event scheduler and
use a timer event on the scheduler to handle the different
timer configurations.

This doesn't change the function right now, but it prepares
the code for having different kinds of events in the future
(i.e. interrupts coming from other devices that are part of
co-simulation.)

While at it, also move time_travel_sleep() to time.c to
reduce the externally visible API surface.

Also, we really should mark time-travel as incompatible with
SMP, even if UML doesn't support SMP yet.

Finally, I noticed a bug while developing this - if we move
time forward due to consuming time while reading the clock,
we might move across the next event and that would cause us
to go backward in time when we then handle that event. Fix
that by invoking the whole event machine in this case, but
in order to simplify this, make reading the clock only cost
something when interrupts are not disabled. Otherwise, we'd
have to hook into the interrupt delivery machinery etc. and
that's somewhat intrusive.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Johannes Berg
2020-02-13 14:26:45 +01:00
committed by Richard Weinberger
parent f185063bff
commit 4b786e24ca
4 changed files with 229 additions and 95 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
arch/um/kernel/process.c
View File

@@ -203,43 +203,6 @@ void initial_thread_cb(void (*proc)(void *), void *arg)
kmalloc_ok = save_kmalloc_ok;
}
static void time_travel_sleep(unsigned long long duration)
{
unsigned long long next = time_travel_time + duration;
if (time_travel_mode != TT_MODE_INFCPU)
os_timer_disable();
while (time_travel_timer_mode == TT_TMR_PERIODIC &&
time_travel_timer_expiry < time_travel_time)
time_travel_set_timer_expiry(time_travel_timer_expiry +
time_travel_timer_interval);
if (time_travel_timer_mode != TT_TMR_DISABLED &&
time_travel_timer_expiry < next) {
if (time_travel_timer_mode == TT_TMR_ONESHOT)
time_travel_set_timer_mode(TT_TMR_DISABLED);
/*
* In basic mode, time_travel_time will be adjusted in
* the timer IRQ handler so it works even when the signal
* comes from the OS timer, see there.
*/
if (time_travel_mode != TT_MODE_BASIC)
time_travel_set_time(time_travel_timer_expiry);
deliver_alarm();
} else {
time_travel_set_time(next);
}
if (time_travel_mode != TT_MODE_INFCPU) {
if (time_travel_timer_mode == TT_TMR_PERIODIC)
os_timer_set_interval(time_travel_timer_interval);
else if (time_travel_timer_mode == TT_TMR_ONESHOT)
os_timer_one_shot(time_travel_timer_expiry - next);
}
}
static void um_idle_sleep(void)
{
unsigned long long duration = UM_NSEC_PER_SEC;