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kernel/poll: Use a separate thread backpointer for triggered work

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The triggered work scheme uses a trick where it overloads the thread
pointer field of the struct poller (which normally stores the ID of
the thread that is blocked in k_poll()) to be able to find the work
queue to which it will submit.

Give it its own pointer field to break this false dependency.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2020-11-05 11:50:47 -08:00 • committed by Anas Nashif
commit 6c82745cb3
2 changed files with 15 additions and 7 deletions
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1
include/kernel.h
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@ -2766,6 +2766,7 @@ struct k_delayed_work {
struct k_work_poll {
struct k_work work;
struct _poller poller;
struct k_thread *thread;
struct k_poll_event *events;
int num_events;
k_work_handler_t real_handler;

21
kernel/poll.c
View file

@ -503,6 +503,8 @@ static void triggered_work_handler(struct k_work *work)
struct k_work_poll *twork =
CONTAINER_OF(work, struct k_work_poll, work);
__ASSERT(twork->poller.thread == NULL, "");//DEBUG
/*
* If callback is not set, the k_work_poll_submit_to_queue()
* already cleared event registrations.
@ -518,7 +520,7 @@ static void triggered_work_handler(struct k_work *work)
/* Drop work ownership and execute real handler. */
handler = twork->real_handler;
twork->poller.thread = NULL;
twork->thread = NULL;
handler(work);
}
@ -527,7 +529,7 @@ static void triggered_work_expiration_handler(struct _timeout *timeout)
struct k_work_poll *twork =
CONTAINER_OF(timeout, struct k_work_poll, timeout);
struct k_work_q *work_q =
CONTAINER_OF(twork->poller.thread, struct k_work_q, thread);
CONTAINER_OF(twork->thread, struct k_work_q, thread);
twork->poller.is_polling = false;
twork->poll_result = -EAGAIN;
@ -588,7 +590,8 @@ void k_work_poll_init(struct k_work_poll *work,
{
k_work_init(&work->work, triggered_work_handler);
work->events = NULL;
work->poller.thread = NULL;
work->poller = (struct _poller){};
work->thread = NULL;
work->real_handler = handler;
z_init_timeout(&work->timeout);
}
@ -607,10 +610,12 @@ int k_work_poll_submit_to_queue(struct k_work_q *work_q,
__ASSERT(events != NULL, "NULL events\n");
__ASSERT(num_events > 0, "zero events\n");
__ASSERT(work->poller.thread == NULL, "");//DEBUG
/* Take overship of the work if it is possible. */
key = k_spin_lock(&lock);
if (work->poller.thread != NULL) {
if (work->poller.thread == &work_q->thread) {
if (work->thread != NULL) {
if (work->thread == &work_q->thread) {
int retval;
retval = triggered_work_cancel(work, key);
@ -625,7 +630,7 @@ int k_work_poll_submit_to_queue(struct k_work_q *work_q,
}
work->poller.is_polling = true;
work->poller.thread = &work_q->thread;
work->thread = &work_q->thread;
work->poller.mode = MODE_NONE;
k_spin_unlock(&lock, key);
@ -699,8 +704,10 @@ int k_work_poll_cancel(struct k_work_poll *work)
k_spinlock_key_t key;
int retval;
__ASSERT(work->poller.thread == NULL, "");//DEBUG
/* Check if the work was submitted. */
if (work == NULL || work->poller.thread == NULL) {
if (work == NULL || work->thread == NULL) {
return -EINVAL;
}