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Commit 86e33a29 authored by James Bottomley's avatar James Bottomley Committed by James Bottomley
Browse files

[SCSI] add shared tag map helpers 



This patch adds support for sharing tag maps at the host level
(i.e. either every queue [LUN] has its own tag map or there's a single
one for the entire host).  This formulation is primarily intended to
help single issue queue hardware, like the aic7xxx

Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent 492dfb48

drivers/scsi/hosts.c

+3 −0
Original line number Diff line number Diff line
@@ -265,6 +265,9 @@ static void scsi_host_dev_release(struct device *dev) 
		destroy_workqueue(shost->work_q);



	scsi_destroy_command_freelist(shost);

	if (shost->bqt)

		blk_free_tags(shost->bqt);



	kfree(shost->shost_data);



	if (parent)

include/scsi/scsi_host.h

+7 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ struct scsi_target; 
struct Scsi_Host;

struct scsi_host_cmd_pool;

struct scsi_transport_template;

struct blk_queue_tags;





/*
@@ -465,6 +466,12 @@ struct Scsi_Host { 
	struct scsi_host_template *hostt;

	struct scsi_transport_template *transportt;



	/*

	 * area to keep a shared tag map (if needed, will be

	 * NULL if not)

	 */

	struct blk_queue_tag	*bqt;



	/*

	 * The following two fields are protected with host_lock;

	 * however, eh routines can safely access during eh processing

include/scsi/scsi_tcq.h

+13 −1
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/blkdev.h>

#include <scsi/scsi_cmnd.h>

#include <scsi/scsi_device.h>

#include <scsi/scsi_host.h>





#define MSG_SIMPLE_TAG	0x20
@@ -66,7 +67,8 @@ static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth) 
		return;



	if (!blk_queue_tagged(sdev->request_queue))

		blk_queue_init_tags(sdev->request_queue, depth, NULL);

		blk_queue_init_tags(sdev->request_queue, depth,

				    sdev->host->bqt);



	scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);

}
@@ -131,4 +133,14 @@ static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag) 
	return sdev->current_cmnd;

}



/**

 * scsi_init_shared_tag_map - create a shared tag map

 * @shost:	the host to share the tag map among all devices

 * @depth:	the total depth of the map

 */

static inline void scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)

{

	shost->bqt = blk_init_tags(depth);

}



#endif /* _SCSI_SCSI_TCQ_H */