fix(vfs): fix eventfd select

components/vfs/test_apps/main/test_vfs_eventfd.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -349,3 +349,48 @@ TEST_CASE("eventfd multiple selects", "[vfs][eventfd]")
     TEST_ASSERT_EQUAL(0, close(fd));
     TEST_ESP_OK(esp_vfs_eventfd_unregister());
 }
+
+typedef struct {
+    int *value;
+    int fd;
+} select_block_task_args_t;
+
+static void select_block_task(void *arg)
+{
+    int fd = ((select_block_task_args_t *)arg)->fd;
+    fd_set read_fds;
+
+    FD_ZERO(&read_fds);
+    FD_SET(fd, &read_fds);
+
+    select(fd + 1, &read_fds, NULL, NULL, NULL);
+    *(((select_block_task_args_t *)arg)->value) = 1;
+    vTaskDelete(NULL);
+}
+
+TEST_CASE("eventfd select block", "[vfs][eventfd]")
+{
+    esp_vfs_eventfd_config_t config = ESP_VFS_EVENTD_CONFIG_DEFAULT();
+    TEST_ESP_OK(esp_vfs_eventfd_register(&config));
+
+    select_block_task_args_t args;
+    args.fd = eventfd(0, 0);
+    TEST_ASSERT_GREATER_OR_EQUAL(0, args.fd);
+    int a = 0;
+    args.value = &a;
+
+    int fd_write = eventfd(0, 0);
+    TEST_ASSERT_GREATER_OR_EQUAL(0, fd_write);
+
+    xTaskCreate(select_block_task, "select_block_task", 2048, &args, 5, NULL);
+    vTaskDelay(pdMS_TO_TICKS(2000));
+
+    uint64_t val = 1;
+    TEST_ASSERT_EQUAL(sizeof(val), write(fd_write, &val, sizeof(val)));
+    vTaskDelay(pdMS_TO_TICKS(2000));
+
+    TEST_ASSERT_EQUAL(0, *(args.value));
+    TEST_ASSERT_EQUAL(0, close(args.fd));
+    TEST_ASSERT_EQUAL(0, close(fd_write));
+    TEST_ESP_OK(esp_vfs_eventfd_unregister());
+}

components/vfs/vfs_eventfd.c

@@ -106,7 +106,7 @@ static esp_err_t event_start_select(int                  nfds,
 
     for (int i = 0; i < nfds; i++) {
         _lock_acquire_recursive(&s_events[i].lock);
-        if (s_events[i].fd == i) {
+        if (s_events[i].fd == i && (FD_ISSET(i, readfds) || FD_ISSET(i, writefds) || FD_ISSET(i, exceptfds))) {
             if (s_events[i].support_isr) {
                 portENTER_CRITICAL(&s_events[i].data_spin_lock);
             }