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zephyr: ll_schedule: remove a spin-lock 

We're now making sure that all ll-scheduler tasks under Zephyr are
only ever accessed from their specific core, tasks to be run on core
1 aren't scheduled or cancelled from core 0, etc. Therefore it isn't
necessary any longer to use a spinlock to protect scheduler data,
just disabling interrupts is enough.

This also fixes a dead-lock on secondary cores. When the last task on
core exits, the respective scheduler thread terminates, and that
happens while it's still protecting the scheduler data. Therefore if
a spinlock is used, trying to take it again after that dead-locks the
core.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
This commit is contained in:
Guennadi Liakhovetski 2021-11-12 14:20:54 +01:00 committed by Liam Girdwood
parent cf3a1163af
commit 001d1ac5ef
1 changed files with 2 additions and 24 deletions
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26
src/schedule/zephyr_ll.c
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@ -25,7 +25,6 @@ DECLARE_TR_CTX(ll_tr, SOF_UUID(zll_sched_uuid), LOG_LEVEL_INFO);
struct zephyr_ll {
struct list_item tasks; /* list of ll tasks */
unsigned int n_tasks; /* task counter */
spinlock_t lock; /* protects the list of tasks and the counter */
struct ll_schedule_domain *ll_domain; /* scheduling domain */
unsigned int core; /* core ID of this instance */
};
@ -39,12 +38,12 @@ struct zephyr_ll_pdata {
static void zephyr_ll_lock(struct zephyr_ll *sch, uint32_t *flags)
{
spin_lock_irq(&sch->lock, *flags);
irq_local_disable(*flags);
}
static void zephyr_ll_unlock(struct zephyr_ll *sch, uint32_t *flags)
{
spin_unlock_irq(&sch->lock, *flags);
irq_local_enable(*flags);
}
static void zephyr_ll_assert_core(const struct zephyr_ll *sch)
@ -271,17 +270,6 @@ static void zephyr_ll_run(void *data)
NOTIFIER_TARGET_CORE_LOCAL, NULL, 0);
}
static void zephyr_ll_init_scheduler_for_first_task(struct zephyr_ll *sch)
{
/*
* If we're adding the first task to the scheduler, it is possible that
* the scheduler has already run before on this core and its thread has
* been aborted while holding the spinlock, so we have to re-initialize
* it.
*/
spinlock_init(&sch->lock);
}
/*
* Called once for periodic tasks or multiple times for one-shot tasks
* TODO: start should be ignored in Zephyr LL scheduler implementation. Tasks
@ -306,16 +294,6 @@ static int zephyr_ll_task_schedule(void *data, struct task *task, uint64_t start
tr_info(&ll_tr, "task add %p %pU priority %d flags 0x%x", task, task->uid,
task->priority, task->flags);
irq_local_disable(flags);
/*
* The task counter is decremented as the last operation in
* zephyr_ll_task_done() before aborting the thread, so just disabling
* local IRQs provides sufficient protection here.
*/
if (!sch->n_tasks)
zephyr_ll_init_scheduler_for_first_task(sch);
irq_local_enable(flags);
zephyr_ll_lock(sch, &flags);
pdata = task->priv_data;