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Merge pull request #6833 from Asmod4n/patch-4

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Improve wakeup tick condition check
This commit is contained in:
Yukihiro "Matz" Matsumoto
2026-05-17 19:02:42 +09:00
committed by GitHub
parent c8dd299ca8 8b63ddbfd1
commit aa25be69d7
1 changed files with 34 additions and 7 deletions
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mrbgems/mruby-task/src/task.c
+34 -7
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@@ -417,8 +417,16 @@ mrb_tick(mrb_state *mrb)
}
}
/* Wake up sleeping tasks whose wakeup time has passed */
if ((int32_t)(wakeup_tick_ - tick_) <= 0) {
/* Wake up sleeping tasks whose wakeup time has passed.
*
* UINT32_MAX is the "no sleepers" sentinel. Without the explicit
* check, (int32_t)(UINT32_MAX - tick_) evaluates negative for the
* first half of the 32-bit range, so the queue walk fires every
* tick with nothing to do. Short-circuiting saves the walk in the
* common no-sleepers case -- benefits every HAL, not just
* tickless ones. */
if (wakeup_tick_ != UINT32_MAX &&
(int32_t)(wakeup_tick_ - tick_) <= 0) {
mrb_task *curr = q_waiting_;
mrb_task *next;
uint32_t next_wakeup = UINT32_MAX;
@@ -567,11 +575,19 @@ sleep_us_impl(mrb_state *mrb, uint32_t usec)
/* Convert microseconds to ticks (tick unit is in milliseconds) */
t->wait.wakeup_tick = tick_ + USEC_TO_TICKS(usec);
/* Update next wakeup time if this task wakes earlier */
if ((int32_t)(t->wait.wakeup_tick - wakeup_tick_) < 0) {
/* Update next wakeup time if this task wakes earlier.
*
* When wakeup_tick_ is UINT32_MAX (no prior sleepers), the
* unsigned subtraction wraps to a small positive value and the
* int32_t cast stays non-negative, so the update is skipped and
* the global stays stale until the next mrb_tick self-heals it.
* Handle the sentinel explicitly so tickless HALs that read this
* field get a consistent value as soon as the sleeper is
* installed. */
if (wakeup_tick_ == UINT32_MAX ||
(int32_t)(t->wait.wakeup_tick - wakeup_tick_) < 0) {
wakeup_tick_ = t->wait.wakeup_tick;
}
q_insert_task(mrb, t);
mrb_task_enable_irq();
@@ -1320,11 +1336,22 @@ resume_task_internal(mrb_state *mrb, mrb_task *t)
}
}
/* Update wakeup_tick if task has sleep reason */
/* Update wakeup_tick if task has sleep reason.
*
* Two fixes here vs the original:
* - The UINT32_MAX sentinel case (see comments in
* sleep_us_impl).
* - The read-modify-write on wakeup_tick_ races with
* mrb_tick, which also rewrites this field. sleep_us_impl
* already wraps its update in the IRQ pair; we need the
* same here to match the locking discipline. */
if (t->reason == MRB_TASK_REASON_SLEEP) {
if ((int32_t)(t->wait.wakeup_tick - wakeup_tick_) < 0) {
mrb_task_disable_irq();
if (wakeup_tick_ == UINT32_MAX ||
(int32_t)(t->wait.wakeup_tick - wakeup_tick_) < 0) {
wakeup_tick_ = t->wait.wakeup_tick;
}
mrb_task_enable_irq();
}
}