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@@ -1,12 +1,22 @@
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/*
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- * Copyright (c) 2006-2021, RT-Thread Development Team
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+ * Copyright (c) 2006-2023, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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* 2021/01/02 bernard the first version
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+ * 2023-07-25 Shell Remove usage of rt_hw_interrupt API in the lwp
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+ * Coding style: remove multiple `return` in a routine
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+ * 2023-08-08 Shell Fix return value of futex(wait); Fix ops that only
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+ * FUTEX_PRIVATE is supported currently
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*/
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+#define DBG_TAG "lwp.futex"
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+#define DBG_LVL DBG_INFO
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+#include <rtdbg.h>
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+
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+#include "lwp_internal.h"
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+#include "lwp_pid.h"
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#include <rtthread.h>
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#include <lwp.h>
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@@ -23,27 +33,24 @@ struct rt_futex
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struct rt_object *custom_obj;
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};
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-static struct rt_mutex _futex_lock;
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-
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-static int futex_system_init(void)
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-{
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- rt_mutex_init(&_futex_lock, "futexList", RT_IPC_FLAG_FIFO);
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- return 0;
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-}
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-INIT_PREV_EXPORT(futex_system_init);
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-
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-rt_err_t futex_destory(void *data)
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+/* must have futex address_search_head taken */
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+static rt_err_t _futex_destroy_locked(void *data)
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{
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rt_err_t ret = -1;
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- rt_base_t level;
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struct rt_futex *futex = (struct rt_futex *)data;
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if (futex)
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{
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- level = rt_hw_interrupt_disable();
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- /* remove futex from futext avl */
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+ /**
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+ * Brief: Delete the futex from lwp address_search_head
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+ *
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+ * Note: Critical Section
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+ * - the lwp (READ. share by thread)
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+ * - the lwp address_search_head (RW. protected by caller. for destroy
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+ * routine, it's always safe because it has already taken a write lock
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+ * to the lwp.)
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+ */
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lwp_avl_remove(&futex->node, (struct lwp_avl_struct **)futex->node.data);
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- rt_hw_interrupt_enable(level);
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/* release object */
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rt_free(futex);
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@@ -52,43 +59,79 @@ rt_err_t futex_destory(void *data)
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return ret;
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}
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-struct rt_futex *futex_create(int *uaddr, struct rt_lwp *lwp)
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+/* must have futex address_search_head taken */
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+static struct rt_futex *_futex_create_locked(int *uaddr, struct rt_lwp *lwp)
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{
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struct rt_futex *futex = RT_NULL;
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struct rt_object *obj = RT_NULL;
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- if (!lwp)
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- {
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- return RT_NULL;
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- }
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- futex = (struct rt_futex *)rt_malloc(sizeof(struct rt_futex));
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- if (!futex)
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- {
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- return RT_NULL;
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- }
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- obj = rt_custom_object_create("futex", (void *)futex, futex_destory);
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- if (!obj)
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+ /**
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+ * Brief: Create a futex under current lwp
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+ *
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+ * Note: Critical Section
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+ * - lwp (READ; share with thread)
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+ */
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+ if (lwp)
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{
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- rt_free(futex);
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- return RT_NULL;
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+ futex = (struct rt_futex *)rt_malloc(sizeof(struct rt_futex));
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+ if (futex)
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+ {
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+ obj = rt_custom_object_create("futex", (void *)futex, _futex_destroy_locked);
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+ if (!obj)
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+ {
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+ rt_free(futex);
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+ futex = RT_NULL;
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+ }
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+ else
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+ {
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+ /**
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+ * Brief: Add futex to user object tree for resource recycling
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+ *
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+ * Note: Critical Section
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+ * - lwp user object tree (RW; protected by API)
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+ * - futex (if the adding is successful, others can find the
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+ * unready futex. However, only the lwp_free will do this,
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+ * and this is protected by the ref taken by the lwp thread
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+ * that the lwp_free will never execute at the same time)
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+ */
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+ if (lwp_user_object_add(lwp, obj))
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+ {
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+ rt_object_delete(obj);
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+ rt_free(futex);
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+ futex = RT_NULL;
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+ }
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+ else
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+ {
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+ futex->uaddr = uaddr;
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+ futex->node.avl_key = (avl_key_t)uaddr;
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+ futex->node.data = &lwp->address_search_head;
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+ futex->custom_obj = obj;
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+ rt_list_init(&(futex->waiting_thread));
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+
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+ /**
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+ * Brief: Insert into futex head
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+ *
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+ * Note: Critical Section
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+ * - lwp address_search_head (RW; protected by caller)
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+ */
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+ lwp_avl_insert(&futex->node, &lwp->address_search_head);
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+ }
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+ }
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+ }
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}
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-
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- futex->uaddr = uaddr;
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- futex->node.avl_key = (avl_key_t)uaddr;
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- futex->node.data = &lwp->address_search_head;
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- futex->custom_obj = obj;
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- rt_list_init(&(futex->waiting_thread));
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-
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- /* insert into futex head */
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- lwp_avl_insert(&futex->node, &lwp->address_search_head);
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return futex;
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}
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-static struct rt_futex *futex_get(void *uaddr, struct rt_lwp *lwp)
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+/* must have futex address_search_head taken */
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+static struct rt_futex *_futex_get_locked(void *uaddr, struct rt_lwp *lwp)
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{
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struct rt_futex *futex = RT_NULL;
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struct lwp_avl_struct *node = RT_NULL;
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+ /**
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+ * Note: Critical Section
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+ * protect lwp address_search_head (READ)
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+ */
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node = lwp_avl_find((avl_key_t)uaddr, lwp->address_search_head);
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if (!node)
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{
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@@ -98,162 +141,213 @@ static struct rt_futex *futex_get(void *uaddr, struct rt_lwp *lwp)
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return futex;
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}
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-int futex_wait(struct rt_futex *futex, int value, const struct timespec *timeout)
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+static int _futex_wait(struct rt_futex *futex, struct rt_lwp *lwp, int value, const struct timespec *timeout)
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{
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- rt_base_t level = 0;
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+ rt_thread_t thread;
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rt_err_t ret = -RT_EINTR;
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+ /**
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+ * Brief: Remove current thread from scheduler, besides appends it to
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+ * the waiting thread list of the futex. If the timeout is specified
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+ * a timer will be setup for current thread
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+ *
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+ * Note: Critical Section
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+ * - futex (RW; Protected by lwp_lock)
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+ * - the local cpu
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+ */
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+ LWP_LOCK(lwp);
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if (*(futex->uaddr) == value)
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{
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- rt_thread_t thread = rt_thread_self();
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+ thread = rt_thread_self();
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+
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+ rt_enter_critical();
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- level = rt_hw_interrupt_disable();
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ret = rt_thread_suspend_with_flag(thread, RT_INTERRUPTIBLE);
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- if (ret < 0)
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+ if (ret == RT_EOK)
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{
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- rt_mutex_release(&_futex_lock);
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- rt_hw_interrupt_enable(level);
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- rt_set_errno(EINTR);
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- return ret;
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+ /**
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+ * Brief: Add current thread into futex waiting thread list
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+ *
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+ * Note: Critical Section
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+ * - the futex waiting_thread list (RW)
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+ */
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+ rt_list_insert_before(&(futex->waiting_thread), &(thread->tlist));
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+
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+ if (timeout)
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+ {
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+ /* start the timer of thread */
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+ rt_int32_t time = timeout->tv_sec * RT_TICK_PER_SECOND + timeout->tv_nsec * RT_TICK_PER_SECOND / NANOSECOND_PER_SECOND;
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+
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+ if (time < 0)
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+ {
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+ time = 0;
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+ }
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+
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+ rt_timer_control(&(thread->thread_timer),
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+ RT_TIMER_CTRL_SET_TIME,
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+ &time);
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+ rt_timer_start(&(thread->thread_timer));
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+ }
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}
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-
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- /* add into waiting thread list */
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- rt_list_insert_before(&(futex->waiting_thread), &(thread->tlist));
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-
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- /* with timeout */
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- if (timeout)
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+ else
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{
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- rt_int32_t time = timeout->tv_sec * RT_TICK_PER_SECOND + timeout->tv_nsec * RT_TICK_PER_SECOND / NANOSECOND_PER_SECOND;
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+ ret = EINTR;
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+ }
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- if (time < 0)
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- {
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- time = 0;
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- }
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+ LWP_UNLOCK(lwp);
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+ rt_exit_critical();
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- /* start the timer of thread */
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- rt_timer_control(&(thread->thread_timer),
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- RT_TIMER_CTRL_SET_TIME,
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- &time);
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- rt_timer_start(&(thread->thread_timer));
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+ if (ret == RT_EOK)
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+ {
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+ /* do schedule */
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+ rt_schedule();
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+ /* check errno */
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+ ret = rt_get_errno();
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}
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- rt_mutex_release(&_futex_lock);
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- rt_hw_interrupt_enable(level);
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-
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- /* do schedule */
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- rt_schedule();
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- ret = thread->error;
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- /* check errno */
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+ ret = ret > 0 ? -ret : ret;
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+ switch (ret)
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+ {
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+ case RT_EOK:
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+ ret = 0;
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+ break;
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+ case -RT_EINTR:
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+ ret = -EINTR;
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+ break;
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+ default:
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+ ret = -EAGAIN;
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+ break;
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+ }
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}
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else
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{
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- rt_mutex_release(&_futex_lock);
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+ LWP_UNLOCK(lwp);
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+ ret = -EAGAIN;
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rt_set_errno(EAGAIN);
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}
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return ret;
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}
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-void futex_wake(struct rt_futex *futex, int number)
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+static long _futex_wake(struct rt_futex *futex, struct rt_lwp *lwp, int number)
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{
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- rt_base_t level = rt_hw_interrupt_disable();
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- while (!rt_list_isempty(&(futex->waiting_thread)) && number)
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- {
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- rt_thread_t thread;
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+ long woken_cnt = 0;
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+ int is_empty = 0;
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+ rt_thread_t thread;
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- thread = rt_list_entry(futex->waiting_thread.next, struct rt_thread, tlist);
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- /* remove from waiting list */
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- rt_list_remove(&(thread->tlist));
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+ /**
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+ * Brief: Wakeup a suspended thread on the futex waiting thread list
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+ *
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+ * Note: Critical Section
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+ * - the futex waiting_thread list (RW)
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+ */
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+ while (number && !is_empty)
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+ {
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+ LWP_LOCK(lwp);
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+ is_empty = rt_list_isempty(&(futex->waiting_thread));
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+ if (!is_empty)
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+ {
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+ thread = rt_list_entry(futex->waiting_thread.next, struct rt_thread, tlist);
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+ /* remove from waiting list */
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+ rt_list_remove(&(thread->tlist));
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- thread->error = RT_EOK;
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- /* resume the suspended thread */
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- rt_thread_resume(thread);
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+ thread->error = RT_EOK;
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+ /* resume the suspended thread */
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+ rt_thread_resume(thread);
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- number--;
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+ number--;
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+ woken_cnt++;
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+ }
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+ LWP_UNLOCK(lwp);
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}
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- rt_mutex_release(&_futex_lock);
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- rt_hw_interrupt_enable(level);
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/* do schedule */
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rt_schedule();
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+ return woken_cnt;
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}
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#include <syscall_generic.h>
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+rt_inline rt_bool_t _timeout_ignored(int op)
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+{
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+ /**
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+ * if (op & (FUTEX_WAKE|FUTEX_FD|FUTEX_WAKE_BITSET|FUTEX_TRYLOCK_PI|FUTEX_UNLOCK_PI)) was TRUE
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+ * `timeout` should be ignored by implementation, according to POSIX futex(2) manual.
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+ * since only FUTEX_WAKE is implemented in rt-smart, only FUTEX_WAKE was omitted currently
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+ */
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+ return (op & (FUTEX_WAKE));
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+}
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+
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sysret_t sys_futex(int *uaddr, int op, int val, const struct timespec *timeout,
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- int *uaddr2, int val3)
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+ int *uaddr2, int val3)
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{
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struct rt_lwp *lwp = RT_NULL;
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struct rt_futex *futex = RT_NULL;
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- int ret = 0;
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- rt_err_t lock_ret = 0;
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+ sysret_t ret = 0;
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if (!lwp_user_accessable(uaddr, sizeof(int)))
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{
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- rt_set_errno(EINVAL);
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- return -RT_EINVAL;
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+ ret = -EINVAL;
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}
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-
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- /**
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- * if (op & (FUTEX_WAKE|FUTEX_FD|FUTEX_WAKE_BITSET|FUTEX_TRYLOCK_PI|FUTEX_UNLOCK_PI)) was TRUE
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- * `timeout` should be ignored by implementation, according to POSIX futex(2) manual.
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- * since only FUTEX_WAKE is implemented in rt-smart, only FUTEX_WAKE was omitted currently
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- */
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- if (timeout && !(op & (FUTEX_WAKE)))
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+ else if (timeout && !_timeout_ignored(op) && !lwp_user_accessable((void *)timeout, sizeof(struct timespec)))
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{
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- if (!lwp_user_accessable((void *)timeout, sizeof(struct timespec)))
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- {
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- rt_set_errno(EINVAL);
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- return -RT_EINVAL;
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- }
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+ ret = -EINVAL;
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}
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- lock_ret = rt_mutex_take_interruptible(&_futex_lock, RT_WAITING_FOREVER);
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- if (lock_ret != RT_EOK)
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+ else
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{
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- rt_set_errno(EAGAIN);
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- return -RT_EINTR;
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+ lwp = lwp_self();
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+ ret = lwp_futex(lwp, futex, uaddr, op, val, timeout);
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}
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- lwp = lwp_self();
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- futex = futex_get(uaddr, lwp);
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+ return ret;
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+}
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+
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+rt_err_t lwp_futex(struct rt_lwp *lwp, struct rt_futex *futex, int *uaddr, int op, int val, const struct timespec *timeout)
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+{
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+ rt_err_t rc = 0;
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+
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+ /**
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+ * Brief: Check if the futex exist, otherwise create a new one
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+ *
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+ * Note: Critical Section
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+ * - lwp address_search_head (READ)
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+ */
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+ LWP_LOCK(lwp);
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+ futex = _futex_get_locked(uaddr, lwp);
|
|
|
if (futex == RT_NULL)
|
|
|
{
|
|
|
/* create a futex according to this uaddr */
|
|
|
- futex = futex_create(uaddr, lwp);
|
|
|
+ futex = _futex_create_locked(uaddr, lwp);
|
|
|
if (futex == RT_NULL)
|
|
|
{
|
|
|
- rt_mutex_release(&_futex_lock);
|
|
|
- rt_set_errno(ENOMEM);
|
|
|
- return -RT_ENOMEM;
|
|
|
- }
|
|
|
- if (lwp_user_object_add(lwp, futex->custom_obj) != 0)
|
|
|
- {
|
|
|
- rt_custom_object_destroy(futex->custom_obj);
|
|
|
- rt_mutex_release(&_futex_lock);
|
|
|
- rt_set_errno(ENOMEM);
|
|
|
- return -RT_ENOMEM;
|
|
|
+ rc = -ENOMEM;
|
|
|
}
|
|
|
}
|
|
|
+ LWP_UNLOCK(lwp);
|
|
|
|
|
|
- switch (op)
|
|
|
+ if (!rc)
|
|
|
{
|
|
|
- case FUTEX_WAIT:
|
|
|
- ret = futex_wait(futex, val, timeout);
|
|
|
- /* _futex_lock is released by futex_wait */
|
|
|
- break;
|
|
|
-
|
|
|
- case FUTEX_WAKE:
|
|
|
- futex_wake(futex, val);
|
|
|
- /* _futex_lock is released by futex_wake */
|
|
|
- break;
|
|
|
-
|
|
|
- default:
|
|
|
- rt_mutex_release(&_futex_lock);
|
|
|
- rt_set_errno(ENOSYS);
|
|
|
- ret = -ENOSYS;
|
|
|
- break;
|
|
|
+ if (!(op & FUTEX_PRIVATE))
|
|
|
+ rc = -ENOSYS;
|
|
|
+ else
|
|
|
+ {
|
|
|
+ op &= ~FUTEX_PRIVATE;
|
|
|
+ switch (op)
|
|
|
+ {
|
|
|
+ case FUTEX_WAIT:
|
|
|
+ rc = _futex_wait(futex, lwp, val, timeout);
|
|
|
+ break;
|
|
|
+ case FUTEX_WAKE:
|
|
|
+ rc = _futex_wake(futex, lwp, val);
|
|
|
+ break;
|
|
|
+ default:
|
|
|
+ LOG_W("User require op=%d which is not implemented", op);
|
|
|
+ rc = -ENOSYS;
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ }
|
|
|
}
|
|
|
|
|
|
- return ret;
|
|
|
+ return rc;
|
|
|
}
|