Add the system call eventfd (#7835)

components/libc/posix/Kconfig

@@ -25,6 +25,11 @@ if RT_USING_POSIX_FS
         bool "Enable I/O Multiplexing select() <sys/select.h>"
         select RT_USING_POSIX_POLL
         default n
+    
+    config RT_USING_POSIX_EVENTFD
+        bool "Enable I/O event eventfd <sys/eventfd.h>"
+        select RT_USING_POSIX_POLL
+        default n
 
     config RT_USING_POSIX_SOCKET
         bool "Enable BSD Socket I/O <sys/socket.h> <netdb.h>"

components/libc/posix/io/eventfd/SConscript

@@ -0,0 +1,14 @@
+# RT-Thread building script for component
+
+from building import *
+
+cwd     = GetCurrentDir()
+src     = []
+CPPPATH = [cwd]
+
+if GetDepend('RT_USING_POSIX_EVENTFD'):
+    src += ['eventfd.c']
+
+group = DefineGroup('POSIX', src, depend = [''], CPPPATH = CPPPATH)
+
+Return('group')

components/libc/posix/io/eventfd/eventfd.c

@@ -0,0 +1,274 @@
+/*
+ * Copyright (c) 2006-2023, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-07-20   zmq810150896   first version
+ */
+
+#include <rtthread.h>
+#include <fcntl.h>
+#include <rtdevice.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <dfs_file.h>
+#include "poll.h"
+#include "eventfd.h"
+
+#define EFD_SEMAPHORE (1 << 0)
+#define EFD_CLOEXEC O_CLOEXEC
+#define EFD_NONBLOCK O_NONBLOCK
+
+#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
+#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
+
+#define ULLONG_MAX  (~0ULL)
+
+#define EVENTFD_MUTEX_NAME "eventfd"
+
+struct eventfd_ctx
+{
+    rt_wqueue_t reader_queue;
+    rt_wqueue_t writer_queue;
+    rt_uint64_t count;
+    unsigned int flags;
+    struct rt_mutex lock;
+};
+
+#ifndef RT_USING_DFS_V2
+static int eventfd_close(struct dfs_file *file);
+static int eventfd_poll(struct dfs_file *file, struct rt_pollreq *req);
+static int eventfd_read(struct dfs_file *file, void *buf, size_t count);
+static int eventfd_write(struct dfs_file *file, const void *buf, size_t count);
+#else
+static int eventfd_close(struct dfs_file *file);
+static int eventfd_poll(struct dfs_file *file, struct rt_pollreq *req);
+static int eventfd_read(struct dfs_file *file, void *buf, size_t count, off_t *pos);
+static int eventfd_write(struct dfs_file *file, const void *buf, size_t count, off_t *pos);
+#endif
+
+static const struct dfs_file_ops eventfd_fops =
+{
+    .close      = eventfd_close,
+    .poll       = eventfd_poll,
+    .read       = eventfd_read,
+    .write      = eventfd_write,
+};
+
+static int eventfd_close(struct dfs_file *file)
+{
+    struct eventfd_ctx *ctx = file->vnode->data;
+
+    rt_mutex_detach(&ctx->lock);
+    rt_free(ctx);
+
+    return 0;
+}
+
+static int eventfd_poll(struct dfs_file *file, struct rt_pollreq *req)
+{
+    struct eventfd_ctx *ctx = (struct eventfd_ctx *)file->vnode->data;
+    int events = 0;
+    rt_uint64_t count;
+
+    count = ctx->count;
+
+    rt_poll_add(&ctx->reader_queue, req);
+    rt_poll_add(&ctx->writer_queue, req);
+
+    if (count > 0)
+        events |= POLLIN;
+
+    if (count == ULLONG_MAX)
+        events |= POLLERR;
+
+    if ((ULLONG_MAX - 1) > count)
+        events |= POLLOUT;
+
+    return events;
+}
+
+#ifndef RT_USING_DFS_V2
+static int eventfd_read(struct dfs_file *file, void *buf, size_t count)
+#else
+static int eventfd_read(struct dfs_file *file, void *buf, size_t count, off_t *pos)
+#endif
+{
+    struct eventfd_ctx *ctx = (struct eventfd_ctx *)file->vnode->data;
+    rt_uint64_t counter_num = 0;
+    rt_uint64_t *buffer;
+
+    if (count < sizeof(counter_num))
+        return -EINVAL;
+
+    buffer = (rt_uint64_t *)buf;
+
+    rt_mutex_take(&ctx->lock, RT_WAITING_FOREVER);
+
+    if (ctx->count == 0)
+    {
+        if (file->flags & O_NONBLOCK)
+        {
+            rt_wqueue_wakeup(&ctx->writer_queue, (void*)POLLOUT);
+            rt_mutex_release(&ctx->lock);
+            return -EAGAIN;
+        }
+        else
+        {
+            /* In this case, when the data is read in blocked mode, when ctx->count is 0, the mutex needs to be released and wait for writing */
+            rt_mutex_release(&ctx->lock);
+            rt_wqueue_wakeup(&ctx->writer_queue, (void*)POLLOUT);
+            rt_wqueue_wait(&ctx->reader_queue, 0, RT_WAITING_FOREVER);
+            rt_mutex_take(&ctx->lock, RT_WAITING_FOREVER);
+        }
+    }
+
+    if (ctx->flags & EFD_SEMAPHORE)
+    {
+        counter_num = 1;
+    }
+    else
+    {
+        counter_num = ctx->count;
+    }
+
+    ctx->count -= counter_num;
+
+    (*buffer) = counter_num;
+
+    rt_mutex_release(&ctx->lock);
+
+    return sizeof(counter_num);
+}
+
+#ifndef RT_USING_DFS_V2
+static int eventfd_write(struct dfs_file *file, const void *buf, size_t count)
+#else
+static int eventfd_write(struct dfs_file *file, const void *buf, size_t count, off_t *pos)
+#endif
+{
+    struct eventfd_ctx *ctx = (struct eventfd_ctx *)file->vnode->data;
+    rt_ssize_t ret = 0;
+
+    rt_uint64_t counter_num;
+
+    if (count < sizeof(counter_num))
+        return -EINVAL;
+
+    counter_num = *(rt_uint64_t *)buf;
+
+    if (counter_num == ULLONG_MAX)
+        return -EINVAL;
+
+    ret = -EAGAIN;
+
+    rt_mutex_take(&ctx->lock, RT_WAITING_FOREVER);
+
+    if ((ULLONG_MAX - ctx->count) > counter_num)
+    {
+        ret = sizeof(counter_num);
+    }
+    else if (!(file->flags & O_NONBLOCK))
+    {
+        for (;;)
+        {
+            if ((ULLONG_MAX - ctx->count) >= counter_num)
+            {
+                ret = sizeof(counter_num);
+                break;
+            }
+            /* Release the mutex to avoid a deadlock */
+            rt_mutex_release(&ctx->lock);
+            rt_wqueue_wait(&ctx->writer_queue, 0, RT_WAITING_FOREVER);
+            rt_wqueue_wakeup(&ctx->reader_queue, (void *)POLLIN);
+            rt_mutex_take(&ctx->lock, RT_WAITING_FOREVER);
+        }
+    }
+
+    if (ret > 0)
+    {
+        ctx->count += counter_num;
+        rt_wqueue_wakeup(&ctx->reader_queue, (void *)POLLIN);
+    }
+
+    rt_mutex_release(&ctx->lock);
+
+    return ret;
+}
+
+static int rt_eventfd_create(struct dfs_file *df, unsigned int count, int flags)
+{
+    struct eventfd_ctx *ctx = RT_NULL;
+    rt_err_t ret = 0;
+
+    ctx = (struct eventfd_ctx *)rt_malloc(sizeof(struct eventfd_ctx));
+    if (ctx == RT_NULL)
+    {
+        ret = -ENOMEM;
+    }
+    else
+    {
+        ctx->count = count;
+        ctx->flags = flags;
+        flags &= EFD_SHARED_FCNTL_FLAGS;
+        flags |= O_RDWR;
+
+        rt_mutex_init(&ctx->lock, EVENTFD_MUTEX_NAME, RT_IPC_FLAG_FIFO);
+        rt_wqueue_init(&ctx->reader_queue);
+        rt_wqueue_init(&ctx->writer_queue);
+
+        df->vnode = (struct dfs_vnode *)rt_malloc(sizeof(struct dfs_vnode));
+        if (df->vnode)
+        {
+            dfs_vnode_init(df->vnode, FT_REGULAR, &eventfd_fops);
+            df->vnode->data = ctx;
+            df->flags = flags;
+        }
+        else
+        {
+            rt_mutex_detach(&ctx->lock);
+            rt_free(ctx);
+            ret = -ENOMEM;
+        }
+    }
+
+    return ret;
+}
+
+static int do_eventfd(unsigned int count, int flags)
+{
+    struct dfs_file *file;
+    int fd;
+    int status;
+    rt_ssize_t ret = 0;
+
+    if (flags & ~EFD_FLAGS_SET)
+        return -RT_EINVAL;
+
+    fd = fd_new();
+    if (fd >= 0)
+    {
+        ret = fd;
+        file = fd_get(fd);
+
+        status = rt_eventfd_create(file, count, flags);
+        if (status < 0)
+        {
+            fd_release(fd);
+            ret = status;
+        }
+    }
+    else
+    {
+        ret = fd;
+    }
+
+    return ret;
+}
+
+int eventfd(unsigned int count, int flags)
+{
+    return do_eventfd(count, flags);
+}

components/libc/posix/io/eventfd/eventfd.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2006-2023, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-07-20    zmq810150896  First version
+ */
+
+#ifndef __EVENTFD_H__
+#define __EVENTFD_H__
+
+int eventfd(unsigned int count, int flags);
+
+#endif /* __EVENTFD_H__ */

components/lwp/lwp_syscall.c

@@ -41,6 +41,7 @@
 #include <sys/utsname.h>
 
 #ifdef RT_USING_DFS
+#include <eventfd.h>
 #include <poll.h>
 #include <sys/select.h>
 #include <dfs_file.h>
@@ -5317,6 +5318,14 @@ sysret_t sys_symlink(const char *existing, const char *new)
     return (ret < 0 ? GET_ERRNO() : ret);
 }
 
+sysret_t sys_eventfd2(unsigned int count, int flags)
+{
+    int ret;
+
+    ret = eventfd(count, flags);
+    return (ret < 0 ? GET_ERRNO() : ret);
+}
+
 static const struct rt_syscall_def func_table[] =
 {
     SYSCALL_SIGN(sys_exit),            /* 01 */
@@ -5548,6 +5557,7 @@ static const struct rt_syscall_def func_table[] =
     SYSCALL_SIGN(sys_sigtimedwait),
     SYSCALL_SIGN(sys_notimpl),
     SYSCALL_SIGN(sys_notimpl),                          /* 190 */
+    SYSCALL_SIGN(sys_eventfd2),
 };
 
 const void *lwp_get_sys_api(rt_uint32_t number)