360 lines
10 KiB
C
Executable File
360 lines
10 KiB
C
Executable File
/*
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* Copyright (c) 2006-2021, 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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* 2016-12-28 Bernard first version
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* 2018-03-09 Bernard Add protection for pt->triggered.
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* 2023-12-04 Shell Fix return code and error verification
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* 2023-12-14 Shell When poll goes to sleep before the waitqueue has added a
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* record and finished enumerating all the fd's, it may be
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* incorrectly woken up. This is basically because the poll
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* mechanism wakeup algorithm does not correctly distinguish
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* the current wait state.
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* 2024-03-29 TroyMitchelle Add all function comments and comments to structure members
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*/
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#include <stdint.h>
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#include <rthw.h>
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#include <rtthread.h>
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#include <dfs_file.h>
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#include "poll.h"
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enum rt_poll_status
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{
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RT_POLL_STAT_INIT, /**< Poll operation initialization status. */
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RT_POLL_STAT_TRIG, /**< Poll operation triggered status. */
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RT_POLL_STAT_WAITING /**< Poll operation waiting status. */
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};
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struct rt_poll_table
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{
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rt_pollreq_t req; /**< Poll request. */
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enum rt_poll_status status; /**< Status of the poll operation. */
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rt_thread_t polling_thread; /**< Polling thread associated with the table. */
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struct rt_poll_node *nodes; /**< Linked list of poll nodes. */
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};
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struct rt_poll_node
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{
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struct rt_wqueue_node wqn; /**< Wait queue node for the poll node. */
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struct rt_poll_table *pt; /**< Pointer to the parent poll table. */
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struct rt_poll_node *next; /**< Pointer to the next poll node. */
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};
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static RT_DEFINE_SPINLOCK(_spinlock);
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/**
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* @brief Wake-up function for the wait queue.
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*
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* This function is invoked when a node in the wait queue needs to be woken up.
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*
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* @param wait Pointer to the wait queue node.
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* @param key Key associated with the wake-up operation.
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* @return Upon successful wake-up, returns 0; otherwise, -1 is returned.
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*/
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static int __wqueue_pollwake(struct rt_wqueue_node *wait, void *key)
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{
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rt_ubase_t level;
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struct rt_poll_node *pn;
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int is_waiting;
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if (key && !((rt_ubase_t)key & wait->key))
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return -1;
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pn = rt_container_of(wait, struct rt_poll_node, wqn);
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level = rt_spin_lock_irqsave(&_spinlock);
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is_waiting = (pn->pt->status == RT_POLL_STAT_WAITING);
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pn->pt->status = RT_POLL_STAT_TRIG;
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rt_spin_unlock_irqrestore(&_spinlock, level);
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if (is_waiting)
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return __wqueue_default_wake(wait, key);
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return -1;
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}
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/**
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* @brief Adds a poll request to the wait queue.
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*
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* This function adds a poll request to the wait queue associated with the specified
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* wait queue and poll request.
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*
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* @param wq Pointer to the wait queue.
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* @param req Pointer to the poll request.
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*/
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static void _poll_add(rt_wqueue_t *wq, rt_pollreq_t *req)
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{
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struct rt_poll_table *pt;
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struct rt_poll_node *node;
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node = (struct rt_poll_node *)rt_malloc(sizeof(struct rt_poll_node));
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if (node == RT_NULL)
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return;
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pt = rt_container_of(req, struct rt_poll_table, req);
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node->wqn.key = req->_key;
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rt_list_init(&(node->wqn.list));
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node->wqn.polling_thread = pt->polling_thread;
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node->wqn.wakeup = __wqueue_pollwake;
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node->next = pt->nodes;
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node->pt = pt;
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pt->nodes = node;
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rt_wqueue_add(wq, &node->wqn);
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}
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/**
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* @brief Initializes a poll table.
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*
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* This function initializes a poll table with the provided poll request, status,
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* and polling thread.
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*
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* @param pt Pointer to the poll table to be initialized.
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*/
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static void poll_table_init(struct rt_poll_table *pt)
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{
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pt->req._proc = _poll_add;
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pt->status = RT_POLL_STAT_INIT;
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pt->nodes = RT_NULL;
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pt->polling_thread = rt_thread_self();
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}
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/**
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* @brief Waits for events on the poll table with a specified timeout.
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*
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* This function waits for events on the poll table with the specified timeout
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* in milliseconds.
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*
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* @param pt Pointer to the poll table.
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* @param msec Timeout value in milliseconds.
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* @return Upon successful completion, returns 0. If the timeout expires, -RT_ETIMEOUT
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* is returned. If the operation is interrupted by a signal, -RT_EINTR is
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* returned.
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*/
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static int poll_wait_timeout(struct rt_poll_table *pt, int msec)
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{
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rt_int32_t timeout;
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int ret = 0;
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struct rt_thread *thread;
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rt_base_t level;
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thread = pt->polling_thread;
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timeout = rt_tick_from_millisecond(msec);
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level = rt_spin_lock_irqsave(&_spinlock);
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if (timeout != 0 && pt->status != RT_POLL_STAT_TRIG)
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{
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if (rt_thread_suspend_with_flag(thread, RT_INTERRUPTIBLE) == RT_EOK)
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{
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if (timeout > 0)
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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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&timeout);
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rt_timer_start(&(thread->thread_timer));
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rt_set_errno(RT_ETIMEOUT);
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}
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else
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{
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rt_set_errno(0);
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}
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pt->status = RT_POLL_STAT_WAITING;
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rt_spin_unlock_irqrestore(&_spinlock, level);
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rt_schedule();
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level = rt_spin_lock_irqsave(&_spinlock);
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if (pt->status == RT_POLL_STAT_WAITING)
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pt->status = RT_POLL_STAT_INIT;
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}
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}
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ret = rt_get_errno();
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if (ret == RT_EINTR)
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ret = -RT_EINTR;
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else if (pt->status == RT_POLL_STAT_TRIG)
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ret = RT_EOK;
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else
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ret = -RT_ETIMEOUT;
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rt_spin_unlock_irqrestore(&_spinlock, level);
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return ret;
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}
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/**
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* @brief Performs poll operation for a single file descriptor.
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*
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* This function performs a poll operation for a single file descriptor and updates
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* the revents field of the pollfd structure accordingly.
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*
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* @param pollfd Pointer to the pollfd structure.
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* @param req Pointer to the poll request.
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* @return Upon successful completion, returns the bitmask of events that occurred.
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* If an error occurs, -1 is returned.
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*/
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static int do_pollfd(struct pollfd *pollfd, rt_pollreq_t *req)
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{
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int mask = 0;
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int fd;
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fd = pollfd->fd;
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if (fd >= 0)
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{
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struct dfs_file *f = fd_get(fd);
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mask = POLLNVAL;
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if (f)
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{
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mask = POLLMASK_DEFAULT;
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if (f->vnode->fops->poll)
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{
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req->_key = pollfd->events | POLLERR | POLLHUP;
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mask = f->vnode->fops->poll(f, req);
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/* dealwith the device return error -1*/
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if (mask < 0)
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{
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pollfd->revents = 0;
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return mask;
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}
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}
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/* Mask out unneeded events. */
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mask &= pollfd->events | POLLERR | POLLHUP;
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}
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}
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pollfd->revents = mask;
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return mask;
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}
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/**
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* @brief Performs the poll operation on an array of file descriptors.
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*
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* This function performs the poll operation on an array of file descriptors and
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* waits for events with the specified timeout.
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*
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* @param fds Pointer to the array of pollfd structures.
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* @param nfds Number of file descriptors in the array.
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* @param pt Pointer to the poll table.
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* @param msec Timeout value in milliseconds.
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* @return Upon successful completion, returns the number of file descriptors
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* for which events were received. If the timeout expires, -RT_ETIMEOUT
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* is returned. If the operation is interrupted by a signal, -RT_EINTR is
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* returned.
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*/
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static int poll_do(struct pollfd *fds, nfds_t nfds, struct rt_poll_table *pt, int msec)
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{
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int num;
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int istimeout = 0;
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nfds_t n;
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struct pollfd *pf;
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int ret = 0;
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if (msec == 0)
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{
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pt->req._proc = RT_NULL;
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istimeout = 1;
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}
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while (1)
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{
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pf = fds;
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num = 0;
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pt->status = RT_POLL_STAT_INIT;
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for (n = 0; n < nfds; n ++)
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{
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ret = do_pollfd(pf, &pt->req);
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if(ret < 0)
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{
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/*dealwith the device return error -1 */
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pt->req._proc = RT_NULL;
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return ret;
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}
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else if(ret > 0)
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{
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num ++;
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pt->req._proc = RT_NULL;
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}
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pf ++;
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}
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pt->req._proc = RT_NULL;
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if (num || istimeout)
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break;
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ret = poll_wait_timeout(pt, msec);
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if (ret == -RT_EINTR)
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return -EINTR;
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else if (ret == -RT_ETIMEOUT)
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istimeout = 1;
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else
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istimeout = 0;
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}
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return num;
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}
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/**
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* @brief Tears down the poll table.
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*
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* This function tears down the poll table by removing all poll nodes associated
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* with it.
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*
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* @param pt Pointer to the poll table.
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*/
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static void poll_teardown(struct rt_poll_table *pt)
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{
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struct rt_poll_node *node, *next;
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next = pt->nodes;
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while (next)
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{
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node = next;
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rt_wqueue_remove(&node->wqn);
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next = node->next;
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rt_free(node);
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}
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}
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/**
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* @brief Performs the poll operation on a set of file descriptors.
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*
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* This function performs the poll operation on a set of file descriptors and
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* waits for events with the specified timeout.
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*
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* @param fds Pointer to the array of pollfd structures.
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* @param nfds Number of file descriptors in the array.
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* @param timeout Timeout value in milliseconds.
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* @return Upon successful completion, returns the number of file descriptors
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* for which events were received. If the timeout expires, 0 is returned.
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* If an error occurs, -1 is returned.
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*/
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int poll(struct pollfd *fds, nfds_t nfds, int timeout)
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{
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int num;
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struct rt_poll_table table;
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poll_table_init(&table);
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num = poll_do(fds, nfds, &table, timeout);
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poll_teardown(&table);
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return num;
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}
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