vfs: Polling

include/zinnia/poll.h

@@ -2,7 +2,11 @@
 
 #pragma once
 
-#include <zinnia/list.h>
+#include <zinnia/atomic.h>
+#include <zinnia/errno.h>
+#include <zinnia/mutex.h>
+#include <zinnia/spin.h>
+#include <zinnia/tailq.h>
 #include <stdint.h>
 #include <uapi/poll.h>
 
@@ -20,7 +24,39 @@ enum poll_flags : uint16_t {
     POLLWRBAND = __POLLWRBAND,
 };
 
-struct poll_event {
-    // TODO
-    list_link(struct poll_event*) next;
+struct task;
+struct poll_table;
+struct poll_event;
+
+struct poll_waiter {
+    struct poll_event* event;
+    struct poll_table* table;
+    tailq_link(struct poll_waiter) link;
+    struct poll_waiter* next;
 };
+
+struct poll_event {
+    struct spinlock lock;
+    tailq_head(struct poll_waiter) waiters;
+};
+
+struct poll_table {
+    struct task* task;
+    void (*notify)(struct poll_table* table);
+    atomic_bool triggered;
+    struct poll_waiter* waiters;
+    struct poll_waiter inline_waiter;
+    bool inline_used;
+    bool interruptible;
+    errno_t error;
+};
+
+void poll_event_init(struct poll_event* event);
+void poll_event_notify(struct poll_event* event);
+
+void poll_table_init(struct poll_table* table);
+void poll_table_init_callback(struct poll_table* table, void (*notify)(struct poll_table* table));
+void poll_table_fini(struct poll_table* table);
+void poll_wait(struct poll_table* table, struct poll_event* event);
+errno_t poll_table_wait(struct poll_table* table, const uint64_t* deadline_ns);
+errno_t poll_table_sleep(struct poll_table* table, mutex_t* lock, const uint64_t* deadline_ns);