From e3e12f52b214121840b44c91de5b3e5af5d3eb84 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Mon, 06 Nov 2023 03:04:41 +0000
Subject: [PATCH] rk3568 rt init
---
kernel/kernel/futex.c | 126 ++++++++++++++++++++++++++++++++----------
1 files changed, 96 insertions(+), 30 deletions(-)
diff --git a/kernel/kernel/futex.c b/kernel/kernel/futex.c
index 3c67da9..81090f7 100644
--- a/kernel/kernel/futex.c
+++ b/kernel/kernel/futex.c
@@ -962,7 +962,9 @@
if (head->next != next) {
/* retain curr->pi_lock for the loop invariant */
raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
+ raw_spin_unlock_irq(&curr->pi_lock);
spin_unlock(&hb->lock);
+ raw_spin_lock_irq(&curr->pi_lock);
put_pi_state(pi_state);
continue;
}
@@ -1573,6 +1575,7 @@
struct task_struct *new_owner;
bool postunlock = false;
DEFINE_WAKE_Q(wake_q);
+ DEFINE_WAKE_Q(wake_sleeper_q);
int ret = 0;
new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
@@ -1622,14 +1625,15 @@
* not fail.
*/
pi_state_update_owner(pi_state, new_owner);
- postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
+ postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q,
+ &wake_sleeper_q);
}
out_unlock:
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
if (postunlock)
- rt_mutex_postunlock(&wake_q);
+ rt_mutex_postunlock(&wake_q, &wake_sleeper_q);
return ret;
}
@@ -2253,6 +2257,16 @@
requeue_pi_wake_futex(this, &key2, hb2);
drop_count++;
continue;
+ } else if (ret == -EAGAIN) {
+ /*
+ * Waiter was woken by timeout or
+ * signal and has set pi_blocked_on to
+ * PI_WAKEUP_INPROGRESS before we
+ * tried to enqueue it on the rtmutex.
+ */
+ this->pi_state = NULL;
+ put_pi_state(pi_state);
+ continue;
} else if (ret) {
/*
* rt_mutex_start_proxy_lock() detected a
@@ -2816,10 +2830,9 @@
if (abs_time) {
to = &timeout;
- hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ?
- CLOCK_REALTIME : CLOCK_MONOTONIC,
- HRTIMER_MODE_ABS);
- hrtimer_init_sleeper(to, current);
+ hrtimer_init_sleeper_on_stack(to, (flags & FLAGS_CLOCKRT) ?
+ CLOCK_REALTIME : CLOCK_MONOTONIC,
+ HRTIMER_MODE_ABS, current);
hrtimer_set_expires_range_ns(&to->timer, *abs_time,
current->timer_slack_ns);
}
@@ -2917,9 +2930,8 @@
if (time) {
to = &timeout;
- hrtimer_init_on_stack(&to->timer, CLOCK_REALTIME,
- HRTIMER_MODE_ABS);
- hrtimer_init_sleeper(to, current);
+ hrtimer_init_sleeper_on_stack(to, CLOCK_REALTIME,
+ HRTIMER_MODE_ABS, current);
hrtimer_set_expires(&to->timer, *time);
}
@@ -2982,7 +2994,7 @@
goto no_block;
}
- rt_mutex_init_waiter(&rt_waiter);
+ rt_mutex_init_waiter(&rt_waiter, false);
/*
* On PREEMPT_RT_FULL, when hb->lock becomes an rt_mutex, we must not
@@ -2998,6 +3010,14 @@
* before __rt_mutex_start_proxy_lock() is done.
*/
raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock);
+ /*
+ * the migrate_disable() here disables migration in the in_atomic() fast
+ * path which is enabled again in the following spin_unlock(). We have
+ * one migrate_disable() pending in the slow-path which is reversed
+ * after the raw_spin_unlock_irq() where we leave the atomic context.
+ */
+ migrate_disable();
+
spin_unlock(q.lock_ptr);
/*
* __rt_mutex_start_proxy_lock() unconditionally enqueues the @rt_waiter
@@ -3006,6 +3026,7 @@
*/
ret = __rt_mutex_start_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter, current);
raw_spin_unlock_irq(&q.pi_state->pi_mutex.wait_lock);
+ migrate_enable();
if (ret) {
if (ret == 1)
@@ -3140,10 +3161,19 @@
* rt_waiter. Also see the WARN in wake_futex_pi().
*/
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+ /*
+ * Magic trickery for now to make the RT migrate disable
+ * logic happy. The following spin_unlock() happens with
+ * interrupts disabled so the internal migrate_enable()
+ * won't undo the migrate_disable() which was issued when
+ * locking hb->lock.
+ */
+ migrate_disable();
spin_unlock(&hb->lock);
/* drops pi_state->pi_mutex.wait_lock */
ret = wake_futex_pi(uaddr, uval, pi_state);
+ migrate_enable();
put_pi_state(pi_state);
@@ -3314,7 +3344,7 @@
{
struct hrtimer_sleeper timeout, *to = NULL;
struct rt_mutex_waiter rt_waiter;
- struct futex_hash_bucket *hb;
+ struct futex_hash_bucket *hb, *hb2;
union futex_key key2 = FUTEX_KEY_INIT;
struct futex_q q = futex_q_init;
int res, ret;
@@ -3330,10 +3360,9 @@
if (abs_time) {
to = &timeout;
- hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ?
- CLOCK_REALTIME : CLOCK_MONOTONIC,
- HRTIMER_MODE_ABS);
- hrtimer_init_sleeper(to, current);
+ hrtimer_init_sleeper_on_stack(to, (flags & FLAGS_CLOCKRT) ?
+ CLOCK_REALTIME : CLOCK_MONOTONIC,
+ HRTIMER_MODE_ABS, current);
hrtimer_set_expires_range_ns(&to->timer, *abs_time,
current->timer_slack_ns);
}
@@ -3342,7 +3371,7 @@
* The waiter is allocated on our stack, manipulated by the requeue
* code while we sleep on uaddr.
*/
- rt_mutex_init_waiter(&rt_waiter);
+ rt_mutex_init_waiter(&rt_waiter, false);
ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE);
if (unlikely(ret != 0))
@@ -3373,20 +3402,55 @@
/* Queue the futex_q, drop the hb lock, wait for wakeup. */
futex_wait_queue_me(hb, &q, to);
- spin_lock(&hb->lock);
- ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
- spin_unlock(&hb->lock);
- if (ret)
- goto out_put_keys;
+ /*
+ * On RT we must avoid races with requeue and trying to block
+ * on two mutexes (hb->lock and uaddr2's rtmutex) by
+ * serializing access to pi_blocked_on with pi_lock.
+ */
+ raw_spin_lock_irq(¤t->pi_lock);
+ if (current->pi_blocked_on) {
+ /*
+ * We have been requeued or are in the process of
+ * being requeued.
+ */
+ raw_spin_unlock_irq(¤t->pi_lock);
+ } else {
+ /*
+ * Setting pi_blocked_on to PI_WAKEUP_INPROGRESS
+ * prevents a concurrent requeue from moving us to the
+ * uaddr2 rtmutex. After that we can safely acquire
+ * (and possibly block on) hb->lock.
+ */
+ current->pi_blocked_on = PI_WAKEUP_INPROGRESS;
+ raw_spin_unlock_irq(¤t->pi_lock);
+
+ spin_lock(&hb->lock);
+
+ /*
+ * Clean up pi_blocked_on. We might leak it otherwise
+ * when we succeeded with the hb->lock in the fast
+ * path.
+ */
+ raw_spin_lock_irq(¤t->pi_lock);
+ current->pi_blocked_on = NULL;
+ raw_spin_unlock_irq(¤t->pi_lock);
+
+ ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
+ spin_unlock(&hb->lock);
+ if (ret)
+ goto out_put_keys;
+ }
/*
- * In order for us to be here, we know our q.key == key2, and since
- * we took the hb->lock above, we also know that futex_requeue() has
- * completed and we no longer have to concern ourselves with a wakeup
- * race with the atomic proxy lock acquisition by the requeue code. The
- * futex_requeue dropped our key1 reference and incremented our key2
- * reference count.
+ * In order to be here, we have either been requeued, are in
+ * the process of being requeued, or requeue successfully
+ * acquired uaddr2 on our behalf. If pi_blocked_on was
+ * non-null above, we may be racing with a requeue. Do not
+ * rely on q->lock_ptr to be hb2->lock until after blocking on
+ * hb->lock or hb2->lock. The futex_requeue dropped our key1
+ * reference and incremented our key2 reference count.
*/
+ hb2 = hash_futex(&key2);
/* Check if the requeue code acquired the second futex for us. */
if (!q.rt_waiter) {
@@ -3395,14 +3459,15 @@
* did a lock-steal - fix up the PI-state in that case.
*/
if (q.pi_state && (q.pi_state->owner != current)) {
- spin_lock(q.lock_ptr);
+ spin_lock(&hb2->lock);
+ BUG_ON(&hb2->lock != q.lock_ptr);
ret = fixup_pi_state_owner(uaddr2, &q, current);
/*
* Drop the reference to the pi state which
* the requeue_pi() code acquired for us.
*/
put_pi_state(q.pi_state);
- spin_unlock(q.lock_ptr);
+ spin_unlock(&hb2->lock);
/*
* Adjust the return value. It's either -EFAULT or
* success (1) but the caller expects 0 for success.
@@ -3421,7 +3486,8 @@
pi_mutex = &q.pi_state->pi_mutex;
ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter);
- spin_lock(q.lock_ptr);
+ spin_lock(&hb2->lock);
+ BUG_ON(&hb2->lock != q.lock_ptr);
if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter))
ret = 0;
--
Gitblit v1.6.2