posix: eventfd: un-inline eventfd_read() and eventfd_write()

There is no major benefit to haveing `eventfd_read()` and
`eventfd_write()` as `static inline` functions and it is
arguably much easier to solve the deadlock bug when they
are not `inline`.

Signed-off-by: Christopher Friedt <cfriedt@meta.com>

include/zephyr/posix/sys/eventfd.h

@@ -51,23 +51,7 @@ int eventfd(unsigned int initval, int flags);
  *
  * @return 0 on success, -1 on error
  */
-static inline int eventfd_read(int fd, eventfd_t *value)
-{
-	const struct fd_op_vtable *efd_vtable;
-	struct k_mutex *lock;
-	ssize_t ret;
-	void *obj;
-
-	obj = z_get_fd_obj_and_vtable(fd, &efd_vtable, &lock);
-
-	(void)k_mutex_lock(lock, K_FOREVER);
-
-	ret = efd_vtable->read(obj, value, sizeof(*value));
-
-	k_mutex_unlock(lock);
-
-	return ret == sizeof(eventfd_t) ? 0 : -1;
-}
+int eventfd_read(int fd, eventfd_t *value);
 
 /**
  * @brief Write to an eventfd
@@ -77,23 +61,7 @@ static inline int eventfd_read(int fd, eventfd_t *value)
  *
  * @return 0 on success, -1 on error
  */
-static inline int eventfd_write(int fd, eventfd_t value)
-{
-	const struct fd_op_vtable *efd_vtable;
-	struct k_mutex *lock;
-	ssize_t ret;
-	void *obj;
-
-	obj = z_get_fd_obj_and_vtable(fd, &efd_vtable, &lock);
-
-	(void)k_mutex_lock(lock, K_FOREVER);
-
-	ret = efd_vtable->write(obj, &value, sizeof(value));
-
-	k_mutex_unlock(lock);
-
-	return ret == sizeof(eventfd_t) ? 0 : -1;
-}
+int eventfd_write(int fd, eventfd_t value);
 
 #ifdef __cplusplus
 }

lib/posix/eventfd.c

@@ -294,3 +294,39 @@ int eventfd(unsigned int initval, int flags)
 	k_mutex_unlock(&eventfd_mtx);
 	return fd;
 }
+
+int eventfd_read(int fd, eventfd_t *value)
+{
+	const struct fd_op_vtable *efd_vtable;
+	struct k_mutex *lock;
+	ssize_t ret;
+	void *obj;
+
+	obj = z_get_fd_obj_and_vtable(fd, &efd_vtable, &lock);
+
+	(void)k_mutex_lock(lock, K_FOREVER);
+
+	ret = efd_vtable->read(obj, value, sizeof(*value));
+
+	k_mutex_unlock(lock);
+
+	return ret == sizeof(eventfd_t) ? 0 : -1;
+}
+
+int eventfd_write(int fd, eventfd_t value)
+{
+	const struct fd_op_vtable *efd_vtable;
+	struct k_mutex *lock;
+	ssize_t ret;
+	void *obj;
+
+	obj = z_get_fd_obj_and_vtable(fd, &efd_vtable, &lock);
+
+	(void)k_mutex_lock(lock, K_FOREVER);
+
+	ret = efd_vtable->write(obj, &value, sizeof(value));
+
+	k_mutex_unlock(lock);
+
+	return ret == sizeof(eventfd_t) ? 0 : -1;
+}