implement a new mechanism for allocating resources on the bus.

instead of optimistically trying to use a resource by executing an
xs and then failing when there's no room for it, this puts things
that want to use the hardware on a runqueue. as resources become
available on the bus then consumers on the runqueue are popped off
and guaranteed access to the resource.

the resources are generally "ccbs" in adapter drivers, so this
abstracts a way for the midlayer to get access to them into something
called iopools.

it also provides a callback api for consumers of resources to use:
the scsi_ioh api for things that want direct access to the ccbs,
and the scsi_xsh api for things that want to issue a scsi_xfer on
the bus. these apis have been modelled on the timeout api.

scsi_xs_get and therefore scsi_scs_cmd have been cut over to using these
apis internally, so if they are allowed to sleep then can wait on the
runqueue for a resource to become available and therefore guarantee that
when executed on an adapter providing an iopool that they will succeed.

ok krw@ beck@ marco@
tested by many including krw@ beck@ mk@ okan@ todd@

1 files changed, 84 insertions, 1 deletions

diff --git a/sys/scsi/scsiconf.h b/sys/scsi/scsiconf.h
index 7a9a9b05f1d..72257b98703 100644
--- a/sys/scsi/scsiconf.h
+++ b/sys/scsi/scsiconf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: scsiconf.h,v 1.120 2010/03/23 01:57:20 krw Exp $	*/
+/*	$OpenBSD: scsiconf.h,v 1.121 2010/04/06 00:58:00 dlg Exp $	*/
 /*	$NetBSD: scsiconf.h,v 1.35 1997/04/02 02:29:38 mycroft Exp $	*/
 
 /*
@@ -327,6 +327,52 @@ struct scsi_device {
 };
 
 /*
+ *
+ */
+
+struct scsi_runq_entry {
+        TAILQ_ENTRY(scsi_runq_entry) e;
+};
+TAILQ_HEAD(scsi_runq, scsi_runq_entry);
+
+struct scsi_iopool;
+
+struct scsi_iohandler {
+	struct scsi_runq_entry entry; /* must be first */
+	u_int onq;
+
+	struct scsi_iopool *pool;
+	void (*handler)(void *, void *);
+	void *cookie;
+};
+
+struct scsi_iopool {
+	/* access to the IOs */
+	void	*iocookie;
+	void	*(*io_get)(void *);
+	void	 (*io_put)(void *, void *);
+	
+	/* the runqueue */
+	struct scsi_runq queue;
+	/* runqueue semaphore */
+	u_int running;
+	/* protection for the runqueue and its semaphore */
+	struct mutex mtx;
+};
+
+/*
+ *
+ */
+
+struct scsi_xshandler {
+	struct scsi_iohandler ioh; /* must be first */
+	u_int onq;
+
+	struct scsi_link *link;
+	void (*handler)(struct scsi_xfer *);
+};
+
+/*
  * This structure describes the connection between an adapter driver and
  * a device driver, and is used by each to call services provided by
  * the other, and to allow generic scsi glue code to call these services
@@ -356,6 +402,7 @@ struct scsi_link {
 #define	SDEV_2NDBUS		0x0400	/* device is a 'second' bus device */
 #define SDEV_UMASS		0x0800	/* device is UMASS SCSI */
 #define SDEV_VIRTUAL		0x1000	/* device is virtualised on the hba */
+#define SDEV_OWN_IOPL		0x2000	/* scsibus */
 	u_int16_t quirks;		/* per-device oddities */
 #define	SDEV_AUTOSAVE		0x0001	/* do implicit SAVEDATAPOINTER on disconnect */
 #define	SDEV_NOSYNC		0x0002	/* does not grok SDTR */
@@ -375,6 +422,11 @@ struct scsi_link {
 	struct	scsi_inquiry_data inqdata; /* copy of INQUIRY data from probe */
 	struct  devid *id;
 	struct	mutex mtx;
+
+	struct	scsi_runq queue;
+	u_int	running;
+
+	struct	scsi_iopool *pool;
 };
 
 int	scsiprint(void *, const char *);
@@ -452,6 +504,8 @@ struct scsi_xfer {
 	struct timeout stimeout;
 	void *cookie;
 	void (*done)(struct scsi_xfer *);
+
+	void *io;			/* adapter io resource */
 };
 
 /*
@@ -551,6 +605,7 @@ int	scsi_interpret_sense(struct scsi_xfer *);
 void		 scsi_buf_enqueue(struct buf *, struct buf *, struct mutex *);
 struct buf	*scsi_buf_dequeue(struct buf *, struct mutex *);
 void		 scsi_buf_requeue(struct buf *, struct buf *, struct mutex *);
+int		 scsi_buf_canqueue(struct buf *, struct mutex *);
 void		 scsi_buf_killqueue(struct buf *, struct mutex *);
 
 void	scsi_xs_show(struct scsi_xfer *);
@@ -581,6 +636,34 @@ int			scsi_xs_sync(struct scsi_xfer *);
 void			scsi_xs_put(struct scsi_xfer *);
 
 /*
+ * iopool stuff
+ */
+void	scsi_iopool_init(struct scsi_iopool *, void *,
+	    void *(*)(void *), void (*)(void *, void *));
+
+void *	scsi_io_get(struct scsi_iopool *, int);
+void	scsi_io_put(struct scsi_iopool *, void *);
+
+/*
+ * default io allocator.
+ */
+void *	scsi_default_get(void *);
+void	scsi_default_put(void *, void *);
+
+/*
+ * io handler interface
+ */
+void	scsi_ioh_set(struct scsi_iohandler *, struct scsi_iopool *,
+	    void (*)(void *, void *), void *);
+void	scsi_ioh_add(struct scsi_iohandler *);
+void	scsi_ioh_del(struct scsi_iohandler *);
+
+void	scsi_xsh_set(struct scsi_xshandler *, struct scsi_link *,
+	    void (*)(struct scsi_xfer *));
+void	scsi_xsh_add(struct scsi_xshandler *);
+void	scsi_xsh_del(struct scsi_xshandler *);
+
+/*
  * Entrypoints for multipathing
  */
 int	mpath_path_attach(struct scsi_link *);