[patch 01/14] syslets: add async.h include file, kernel-side API definitions

[patch 01/14] syslets: add async.h include file, kernel-side API definitions

[Ingo Molnar]

From: Ingo Molnar <mingo@elte.hu>

add include/linux/async.h which contains the kernel-side API
declarations.

it also provides NOP stubs for the !CONFIG_ASYNC_SUPPORT case.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
 include/linux/async.h |   96 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)

Index: linux/include/linux/async.h
===================================================================
--- /dev/null
+++ linux/include/linux/async.h
@@ -0,0 +1,96 @@
+#ifndef _LINUX_ASYNC_H
+#define _LINUX_ASYNC_H
+
+#include <linux/completion.h>
+#include <linux/compiler.h>
+
+/*
+ * The syslet subsystem - asynchronous syscall execution support.
+ *
+ * Generic kernel API definitions:
+ */
+
+struct syslet_uatom;
+struct async_thread;
+struct async_head;
+
+/*
+ * The syslet subsystem - asynchronous syscall execution support.
+ *
+ * Syslet-subsystem internal definitions:
+ */
+
+/*
+ * The kernel-side copy of a syslet atom - with arguments expanded:
+ */
+struct syslet_atom {
+	unsigned long				flags;
+	unsigned long				nr;
+	long __user				*ret_ptr;
+	struct syslet_uatom	__user		*next;
+	unsigned long				args[6];
+};
+
+/*
+ * The 'async head' is the thread which has user-space context (ptregs)
+ * 'below it' - this is the one that can return to user-space:
+ */
+struct async_head {
+	spinlock_t				lock;
+	struct task_struct			*user_task;
+
+	struct list_head			ready_async_threads;
+	struct list_head			busy_async_threads;
+
+	long					events_left;
+	wait_queue_head_t			wait;
+
+	struct async_head_user	__user		*ahu;
+	struct syslet_uatom	__user		**completion_ring;
+	unsigned long				curr_ring_idx;
+	unsigned long				max_ring_idx;
+	unsigned long				ring_size_bytes;
+
+	unsigned int				nr_threads;
+	unsigned int				max_nr_threads;
+
+	unsigned long		__user		*new_stack;
+	unsigned long				new_eip;
+	struct completion			start_done;
+	struct completion			exit_done;
+};
+
+/*
+ * The 'async thread' is either a newly created async thread or it is
+ * an 'ex-head' - it cannot return to user-space and only has kernel
+ * context.
+ */
+struct async_thread {
+	struct task_struct			*task;
+	struct syslet_uatom	__user		*work;
+	unsigned long				user_stack;
+	unsigned long				user_eip;
+	struct async_head			*ah;
+
+	struct list_head			entry;
+
+	unsigned int				exit;
+};
+
+#ifdef CONFIG_ASYNC_SUPPORT
+extern void async_init(struct task_struct *t);
+extern void async_exit(struct task_struct *t);
+extern void __async_schedule(struct task_struct *t);
+#else /* !CONFIG_ASYNC_SUPPORT */
+static inline void async_init(struct task_struct *t)
+{
+}
+static inline void async_exit(struct task_struct *t)
+{
+}
+static inline void __async_schedule(struct task_struct *t)
+{
+}
+#endif /* !CONFIG_ASYNC_SUPPORT */
+
+#endif