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ta_set_timeout can fail to set an alarm (#2127)

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* ta_set_timeout can fail to set an alarm

If alarm_pool_irq_handler takes <1us between handling an alarm and
calling ta_set_timeout then no alarms will be set as it will appear as
if an earlier alarm is already armedi before the target time.

Make sure ta_set_timeout always leaves with an alarm set by checking the
armed status.

Fixes #2118

* ta_disable_irq_handler should unarm its timer
This commit is contained in:
Peter Harper 2024-12-06 16:39:04 +00:00 • committed by GitHub
parent ba7aa3f075
commit 969f5895aa
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
2 changed files with 42 additions and 1 deletions
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4
src/rp2_common/pico_time_adapter/include/pico/time_adapter.h
View file

@ -48,7 +48,8 @@ static inline void ta_set_timeout(alarm_pool_timer_t *timer, uint alarm_num, int
// 2. If we just passed the target time, then time_til_target will be high, meaning we will
// likely not do the update, but this is OK since the caller who has the full 64 bits
// must check if the target time has passed when we return anyway to avoid races.
if (time_til_target < time_til_alarm) {
// 3. We should never leave here without an alarm being armed
if (time_til_target < time_til_alarm || (timer_hw_from_timer(timer)->armed & (1 << alarm_num)) == 0) {
timer_hw_from_timer(timer)->alarm[alarm_num] = (uint32_t) target;
}
}
@ -75,6 +76,7 @@ static inline void ta_enable_irq_handler(alarm_pool_timer_t *timer, uint alarm_n
static inline void ta_disable_irq_handler(alarm_pool_timer_t *timer, uint alarm_num, irq_handler_t irq_handler) {
uint irq_num = timer_hardware_alarm_get_irq_num(timer, alarm_num);
timer_hw_from_timer(timer)->armed = 1u << alarm_num; // disarm the timer
hw_clear_bits(&timer_hw_from_timer(timer)->inte, 1u << alarm_num);
irq_set_enabled(irq_num, true);
irq_remove_handler(irq_num, irq_handler);

39
test/pico_time_test/pico_time_test.c
View file

@ -8,6 +8,7 @@
#include <stdlib.h>
#include <string.h>
#include <hardware/sync.h>
#include "hardware/clocks.h"
#include "pico/stdlib.h"
#include "pico/test.h"
// Include sys/types.h before inttypes.h to work around issue with
@ -74,6 +75,7 @@ static bool repeating_timer_callback(struct repeating_timer *t) {
int issue_195_test(void);
int issue_1812_test(void);
int issue_1953_test(void);
int issue_2118_test(void);
int main() {
setup_default_uart();
@ -246,6 +248,8 @@ int main() {
issue_1953_test();
issue_2118_test();
PICOTEST_END_TEST();
}
@ -325,3 +329,38 @@ int issue_1953_test(void) {
PICOTEST_END_SECTION();
return 0;
}
static int counter_2118;
static bool timer_callback_issue_2118(repeating_timer_t *rt) {
counter_2118++;
return true;
}
int issue_2118_test(void) {
PICOTEST_START_SECTION("Issue #2118 defect - failure to set an alarm");
// this problem only happens when running the clock fast as it requires the time between
// alarm_pool_irq_handler handling an alarm and setting the next alarm to be <1us
set_sys_clock_hz(200 * MHZ, true);
setup_default_uart();
alarm_pool_t *pool = alarm_pool_create(2, 1);
repeating_timer_t timer;
alarm_pool_add_repeating_timer_ms(pool, -20, timer_callback_issue_2118, NULL, &timer);
int iterations = 0;
while(iterations < 100) {
iterations++;
sleep_ms(20);
}
PICOTEST_CHECK(counter_2118 >= 100, "Repeating timer failure");
alarm_pool_destroy(pool);
hard_assert(timer_hw->armed == 0); // check destroying the pool unarms its timer
set_sys_clock_hz(SYS_CLK_HZ, true);
setup_default_uart();
PICOTEST_END_SECTION();
return 0;
}