Mailing List Archive

From: Ingo Molnar <mingo@elte.hu>

add include/linux/syslet.h which contains the user-space API/ABI
declarations. Add the new header to include/linux/Kbuild as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
include/linux/Kbuild | 1
include/linux/syslet.h | 136 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 137 insertions(+)

Index: linux/include/linux/Kbuild
===================================================================
--- linux.orig/include/linux/Kbuild
+++ linux/include/linux/Kbuild
@@ -140,6 +140,7 @@ header-y += sockios.h
header-y += som.h
header-y += sound.h
header-y += synclink.h
+header-y += syslet.h
header-y += telephony.h
header-y += termios.h
header-y += ticable.h
Index: linux/include/linux/syslet.h
===================================================================
--- /dev/null
+++ linux/include/linux/syslet.h
@@ -0,0 +1,136 @@
+#ifndef _LINUX_SYSLET_H
+#define _LINUX_SYSLET_H
+/*
+ * The syslet subsystem - asynchronous syscall execution support.
+ *
+ * Started by Ingo Molnar:
+ *
+ * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * User-space API/ABI definitions:
+ */
+
+/*
+ * This is the 'Syslet Atom' - the basic unit of execution
+ * within the syslet framework. A syslet always represents
+ * a single system-call plus its arguments, plus has conditions
+ * attached to it that allows the construction of larger
+ * programs from these atoms. User-space variables can be used
+ * (for example a loop index) via the special sys_umem*() syscalls.
+ *
+ * Arguments are implemented via pointers to arguments. This not
+ * only increases the flexibility of syslet atoms (multiple syslets
+ * can share the same variable for example), but is also an
+ * optimization: copy_uatom() will only fetch syscall parameters
+ * up until the point it meets the first NULL pointer. 50% of all
+ * syscalls have 2 or less parameters (and 90% of all syscalls have
+ * 4 or less parameters).
+ *
+ * [. Note: since the argument array is at the end of the atom, and the
+ * kernel will not touch any argument beyond the final NULL one, atoms
+ * might be packed more tightly. (the only special case exception to
+ * this rule would be SKIP_TO_NEXT_ON_STOP atoms, where the kernel will
+ * jump a full syslet_uatom number of bytes.) ]
+ */
+struct syslet_uatom {
+ unsigned long flags;
+ unsigned long nr;
+ long __user *ret_ptr;
+ struct syslet_uatom __user *next;
+ unsigned long __user *arg_ptr[6];
+ /*
+ * User-space can put anything in here, kernel will not
+ * touch it:
+ */
+ void __user *private;
+};
+
+/*
+ * Flags to modify/control syslet atom behavior:
+ */
+
+/*
+ * Immediately queue this syslet asynchronously - do not even
+ * attempt to execute it synchronously in the user context:
+ */
+#define SYSLET_ASYNC 0x00000001
+
+/*
+ * Never queue this syslet asynchronously - even if synchronous
+ * execution causes a context-switching:
+ */
+#define SYSLET_SYNC 0x00000002
+
+/*
+ * Do not queue the syslet in the completion ring when done.
+ *
+ * ( the default is that the final atom of a syslet is queued
+ * in the completion ring. )
+ *
+ * Some syscalls generate implicit completion events of their
+ * own.
+ */
+#define SYSLET_NO_COMPLETE 0x00000004
+
+/*
+ * Execution control: conditions upon the return code
+ * of the previous syslet atom. 'Stop' means syslet
+ * execution is stopped and the atom is put into the
+ * completion ring:
+ */
+#define SYSLET_STOP_ON_NONZERO 0x00000008
+#define SYSLET_STOP_ON_ZERO 0x00000010
+#define SYSLET_STOP_ON_NEGATIVE 0x00000020
+#define SYSLET_STOP_ON_NON_POSITIVE 0x00000040
+
+#define SYSLET_STOP_MASK \
+ ( SYSLET_STOP_ON_NONZERO | \
+ SYSLET_STOP_ON_ZERO | \
+ SYSLET_STOP_ON_NEGATIVE | \
+ SYSLET_STOP_ON_NON_POSITIVE )
+
+/*
+ * Special modifier to 'stop' handling: instead of stopping the
+ * execution of the syslet, the linearly next syslet is executed.
+ * (Normal execution flows along atom->next, and execution stops
+ * if atom->next is NULL or a stop condition becomes true.)
+ *
+ * This is what allows true branches of execution within syslets.
+ */
+#define SYSLET_SKIP_TO_NEXT_ON_STOP 0x00000080
+
+/*
+ * This is the (per-user-context) descriptor of the async completion
+ * ring. This gets registered via sys_async_register().
+ */
+struct async_head_user {
+ /*
+ * Pointers to completed async syslets (i.e. syslets that
+ * generated a cachemiss and went async, returning -EASYNCSYSLET
+ * to the user context by sys_async_exec()) are queued here.
+ * Syslets that were executed synchronously are not queued here.
+ *
+ * Note: the final atom that generated the exit condition is
+ * queued here. Normally this would be the last atom of a syslet.
+ */
+ struct syslet_uatom __user **completion_ring;
+ /*
+ * Ring size in bytes:
+ */
+ unsigned long ring_size_bytes;
+
+ /*
+ * Maximum number of asynchronous contexts the kernel creates.
+ *
+ * -1UL has a special meaning: the kernel manages the optimal
+ * size of the async pool.
+ *
+ * Note: this field should be valid for the lifetime of async
+ * processing, because future kernels detect changes to this
+ * field. (enabling user-space to control the size of the async
+ * pool in a low-overhead fashion)
+ */
+ unsigned long max_nr_threads;
+};
+
+#endif
-
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