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posix: pthread: implement pthread spinlocks
pthread_spinlock_t support is part of the base threading requirement. Signed-off-by: Christopher Friedt <[email protected]>
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‎include/zephyr/posix/posix_types.h

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@@ -55,6 +55,7 @@ typedef struct pthread_attr pthread_attr_t;
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BUILD_ASSERT(sizeof(pthread_attr_t) >= sizeof(struct pthread_attr));
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typedef uint32_t pthread_t;
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typedef uint32_t pthread_spinlock_t;
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/* Semaphore */
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typedef struct k_sem sem_t;

‎include/zephyr/posix/pthread.h

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@@ -25,6 +25,10 @@ extern "C" {
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#define PTHREAD_CREATE_DETACHED 0
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#define PTHREAD_CREATE_JOINABLE 1
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/* Pthread resource visibility */
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#define PTHREAD_PROCESS_PRIVATE 0
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#define PTHREAD_PROCESS_SHARED 1
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/* Pthread cancellation */
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#define _PTHREAD_CANCEL_POS 0
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#define PTHREAD_CANCEL_ENABLE (0U << _PTHREAD_CANCEL_POS)
@@ -495,6 +499,45 @@ int pthread_setname_np(pthread_t thread, const char *name);
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*/
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int pthread_getname_np(pthread_t thread, char *name, size_t len);
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#ifdef CONFIG_PTHREAD_IPC
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/**
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* @brief Destroy a pthread_spinlock_t.
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*
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* See IEEE 1003.1
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*/
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int pthread_spin_destroy(pthread_spinlock_t *lock);
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/**
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* @brief Initialize a thread_spinlock_t.
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*
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* See IEEE 1003.1
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*/
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int pthread_spin_init(pthread_spinlock_t *lock, int pshared);
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/**
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* @brief Lock a previously initialized thread_spinlock_t.
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*
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* See IEEE 1003.1
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*/
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int pthread_spin_lock(pthread_spinlock_t *lock);
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/**
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* @brief Attempt to lock a previously initialized thread_spinlock_t.
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*
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* See IEEE 1003.1
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*/
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int pthread_spin_trylock(pthread_spinlock_t *lock);
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/**
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* @brief Unlock a previously locked thread_spinlock_t.
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*
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* See IEEE 1003.1
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*/
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int pthread_spin_unlock(pthread_spinlock_t *lock);
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#endif
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#ifdef __cplusplus
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}
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#endif

‎lib/posix/CMakeLists.txt

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@@ -26,6 +26,7 @@ zephyr_library_sources_ifdef(CONFIG_PTHREAD_IPC pthread_mutex.c)
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zephyr_library_sources_ifdef(CONFIG_PTHREAD_IPC pthread_barrier.c)
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zephyr_library_sources_ifdef(CONFIG_PTHREAD_IPC pthread.c)
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zephyr_library_sources_ifdef(CONFIG_PTHREAD_IPC pthread_sched.c)
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zephyr_library_sources_ifdef(CONFIG_PTHREAD_IPC pthread_spinlock.c)
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zephyr_library_sources_ifdef(CONFIG_POSIX_CLOCK clock.c)
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zephyr_library_sources_ifdef(CONFIG_POSIX_CLOCK nanosleep.c)
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zephyr_library_sources_ifdef(CONFIG_POSIX_CLOCK sleep.c)

‎lib/posix/Kconfig

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@@ -74,6 +74,13 @@ config MAX_PTHREAD_BARRIER_COUNT
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help
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Maximum number of simultaneously active keys in a POSIX application.
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config MAX_PTHREAD_SPINLOCK_COUNT
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int "Maximum simultaneously active spinlocks in a POSIX application"
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default 5
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range 0 255
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help
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Maximum number of simultaneously active spinlocks in a POSIX application.
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config SEM_VALUE_MAX
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int "Maximum semaphore limit"
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default 32767

‎lib/posix/pthread_spinlock.c

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@@ -0,0 +1,161 @@
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/*
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* Copyright (c) 2023, Meta
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include "posix_internal.h"
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#include <zephyr/init.h>
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#include <zephyr/kernel.h>
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#include <zephyr/posix/pthread.h>
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#include <zephyr/sys/bitarray.h>
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union _spinlock_storage {
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struct k_spinlock lock;
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uint8_t byte;
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};
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#if !defined(CONFIG_SMP) && !defined(CONFIG_SPIN_VALIDATE)
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BUILD_ASSERT(sizeof(struct k_spinlock) == 0,
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"please remove the _spinlock_storage workaround if, at some point, k_spinlock is no "
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"longer zero bytes when CONFIG_SMP=n && CONFIG_SPIN_VALIDATE=n");
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#endif
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static union _spinlock_storage posix_spinlock_pool[CONFIG_MAX_PTHREAD_SPINLOCK_COUNT];
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static k_spinlock_key_t posix_spinlock_key[CONFIG_MAX_PTHREAD_SPINLOCK_COUNT];
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SYS_BITARRAY_DEFINE_STATIC(posix_spinlock_bitarray, CONFIG_MAX_PTHREAD_SPINLOCK_COUNT);
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/*
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* We reserve the MSB to mark a pthread_spinlock_t as initialized (from the
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* perspective of the application). With a linear space, this means that
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* the theoretical pthread_spinlock_t range is [0,2147483647].
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*/
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BUILD_ASSERT(CONFIG_MAX_PTHREAD_SPINLOCK_COUNT < PTHREAD_OBJ_MASK_INIT,
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"CONFIG_MAX_PTHREAD_SPINLOCK_COUNT is too high");
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static inline size_t posix_spinlock_to_offset(struct k_spinlock *l)
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{
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return (union _spinlock_storage *)l - posix_spinlock_pool;
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}
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static inline size_t to_posix_spinlock_idx(pthread_spinlock_t lock)
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{
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return mark_pthread_obj_uninitialized(lock);
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}
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static struct k_spinlock *get_posix_spinlock(pthread_spinlock_t *lock)
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{
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size_t bit;
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int actually_initialized;
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if (lock == NULL) {
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return NULL;
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}
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/* if the provided spinlock does not claim to be initialized, its invalid */
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bit = to_posix_spinlock_idx(*lock);
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if (!is_pthread_obj_initialized(*lock)) {
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return NULL;
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}
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/* Mask off the MSB to get the actual bit index */
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if (sys_bitarray_test_bit(&posix_spinlock_bitarray, bit, &actually_initialized) < 0) {
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return NULL;
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}
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if (actually_initialized == 0) {
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/* The spinlock claims to be initialized but is actually not */
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return NULL;
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}
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return (struct k_spinlock *)&posix_spinlock_pool[bit];
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}
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int pthread_spin_init(pthread_spinlock_t *lock, int pshared)
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{
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int ret;
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size_t bit;
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if (lock == NULL ||
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!(pshared == PTHREAD_PROCESS_PRIVATE || pshared == PTHREAD_PROCESS_SHARED)) {
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/* not specified as part of POSIX but this is the Linux behavior */
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return EINVAL;
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}
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ret = sys_bitarray_alloc(&posix_spinlock_bitarray, 1, &bit);
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if (ret < 0) {
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return ENOMEM;
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}
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*lock = mark_pthread_obj_initialized(bit);
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return 0;
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}
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int pthread_spin_destroy(pthread_spinlock_t *lock)
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{
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int err;
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size_t bit;
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struct k_spinlock *l;
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l = get_posix_spinlock(lock);
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if (l == NULL) {
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/* not specified as part of POSIX but this is the Linux behavior */
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return EINVAL;
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}
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bit = posix_spinlock_to_offset(l);
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err = sys_bitarray_free(&posix_spinlock_bitarray, 1, bit);
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__ASSERT_NO_MSG(err == 0);
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return 0;
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}
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int pthread_spin_lock(pthread_spinlock_t *lock)
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{
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size_t bit;
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struct k_spinlock *l;
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l = get_posix_spinlock(lock);
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if (l == NULL) {
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/* not specified as part of POSIX but this is the Linux behavior */
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return EINVAL;
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}
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bit = posix_spinlock_to_offset(l);
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posix_spinlock_key[bit] = k_spin_lock(l);
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return 0;
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}
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int pthread_spin_trylock(pthread_spinlock_t *lock)
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{
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size_t bit;
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struct k_spinlock *l;
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l = get_posix_spinlock(lock);
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if (l == NULL) {
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/* not specified as part of POSIX but this is the Linux behavior */
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return EINVAL;
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}
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bit = posix_spinlock_to_offset(l);
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return k_spin_trylock(l, &posix_spinlock_key[bit]);
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}
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int pthread_spin_unlock(pthread_spinlock_t *lock)
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{
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size_t bit;
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struct k_spinlock *l;
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l = get_posix_spinlock(lock);
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if (l == NULL) {
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/* not specified as part of POSIX but this is the Linux behavior */
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return EINVAL;
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}
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bit = posix_spinlock_to_offset(l);
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k_spin_unlock(l, posix_spinlock_key[bit]);
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return 0;
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}

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