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kernel/sched: Add missing lock around waitq unpend calls

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The two calls to unpend a thread from a wait queue were inexplicably*
unsynchronized, as James Harris discovered.  Rework them to call the
lowest level primities so we can wrap the process inside the scheduler
lock.

Fixes #32136

* I took a brief look.  What seems to have happened here is that these
  were originally synchronized via an implicit from an outer caller
  (remember the original Uniprocessor irq_lock() API is a recursive
  lock), and they were mostly implemented in terms of middle-level
  calls that were themselves locked.  So those got ported over to the
  newer spinlock but the outer wrapper layer got forgotten.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2021-02-09 16:47:47 -08:00 • committed by Anas Nashif
commit 604f0f44b6
2 changed files with 24 additions and 14 deletions
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12
kernel/include/ksched.h
View file

@ -41,6 +41,7 @@ void z_move_thread_to_end_of_prio_q(struct k_thread *thread);
void z_remove_thread_from_ready_q(struct k_thread *thread); void z_remove_thread_from_ready_q(struct k_thread *thread);
int z_is_thread_time_slicing(struct k_thread *thread); int z_is_thread_time_slicing(struct k_thread *thread);
void z_unpend_thread_no_timeout(struct k_thread *thread); void z_unpend_thread_no_timeout(struct k_thread *thread);
struct k_thread *z_unpend1_no_timeout(_wait_q_t *wait_q);
int z_pend_curr(struct k_spinlock *lock, k_spinlock_key_t key, int z_pend_curr(struct k_spinlock *lock, k_spinlock_key_t key,
_wait_q_t *wait_q, k_timeout_t timeout); _wait_q_t *wait_q, k_timeout_t timeout);
int z_pend_curr_irqlock(uint32_t key, _wait_q_t *wait_q, k_timeout_t timeout); int z_pend_curr_irqlock(uint32_t key, _wait_q_t *wait_q, k_timeout_t timeout);
@ -302,15 +303,4 @@ static ALWAYS_INLINE bool z_is_thread_timeout_expired(struct k_thread *thread)
#endif #endif
} }
static inline struct k_thread *z_unpend1_no_timeout(_wait_q_t *wait_q)
{
struct k_thread *thread = z_find_first_thread_to_unpend(wait_q, NULL);
if (thread != NULL) {
z_unpend_thread_no_timeout(thread);
}
return thread;
}
#endif /* ZEPHYR_KERNEL_INCLUDE_KSCHED_H_ */ #endif /* ZEPHYR_KERNEL_INCLUDE_KSCHED_H_ */

26
kernel/sched.c
View file

@ -766,12 +766,32 @@ int z_pend_curr(struct k_spinlock *lock, k_spinlock_key_t key,
return z_swap(lock, key); return z_swap(lock, key);
} }
struct k_thread *z_unpend1_no_timeout(_wait_q_t *wait_q)
{
struct k_thread *thread = NULL;
LOCKED(&sched_spinlock) {
thread = _priq_wait_best(&wait_q->waitq);
if (thread != NULL) {
unpend_thread_no_timeout(thread);
}
}
return thread;
}
struct k_thread *z_unpend_first_thread(_wait_q_t *wait_q) struct k_thread *z_unpend_first_thread(_wait_q_t *wait_q)
{ {
struct k_thread *thread = z_unpend1_no_timeout(wait_q); struct k_thread *thread = NULL;
if (thread != NULL) { LOCKED(&sched_spinlock) {
(void)z_abort_thread_timeout(thread); thread = _priq_wait_best(&wait_q->waitq);
if (thread != NULL) {
unpend_thread_no_timeout(thread);
(void)z_abort_thread_timeout(thread);
}
} }
return thread; return thread;