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Commit d4f5d79e authored by Sebastian Ott's avatar Sebastian Ott Committed by Martin Schwidefsky
Browse files

s390/css: reduce stsch calls 



Both css_evaluate_new_subchannel and cio_validate_subchannel used
stsch and css_sch_is_valid to check for a valid device.

Reduce stsch calls during subchannel evaluation by re-using schib
data. Also the type/devno valid information is only checked once.

Signed-off-by: default avatarSebastian Ott <sebott@linux.ibm.com>
Reviewed-by: default avatarPeter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 05b217f4

drivers/s390/cio/cio.c

+6 −59
Original line number Diff line number Diff line
@@ -526,64 +526,6 @@ int cio_disable_subchannel(struct subchannel *sch) 
}

EXPORT_SYMBOL_GPL(cio_disable_subchannel);



/**

 * cio_validate_subchannel - basic validation of subchannel

 * @schid: subchannel id

 * @schib: subchannel information block to be filled out

 *

 * Check if subchannel is valid and should be used.

 * Return codes:

 *   0 on success

 *   -ENXIO for non-defined subchannels

 *   -ENODEV for invalid subchannels or blacklisted devices

 *   -EIO for subchannels in an invalid subchannel set

 */

int cio_validate_subchannel(struct subchannel_id schid, struct schib *schib)

{

	char dbf_txt[15];

	int ccode;

	int err;



	sprintf(dbf_txt, "valsch%x", schid.sch_no);

	CIO_TRACE_EVENT(4, dbf_txt);



	/*

	 * The first subchannel that is not-operational (ccode==3)

	 * indicates that there aren't any more devices available.

	 * If stsch gets an exception, it means the current subchannel set

	 * is not valid.

	 */

	ccode = stsch(schid, schib);

	if (ccode) {

		err = (ccode == 3) ? -ENXIO : ccode;

		goto out;

	}



	switch (schib->pmcw.st) {

	case SUBCHANNEL_TYPE_IO:

	case SUBCHANNEL_TYPE_MSG:

		if (!css_sch_is_valid(schib))

			err = -ENODEV;

		else if (is_blacklisted(schid.ssid, schib->pmcw.dev)) {

			CIO_MSG_EVENT(6, "Blacklisted device detected "

				      "at devno %04X, subchannel set %x\n",

				      schib->pmcw.dev, schid.ssid);

			err = -ENODEV;

		} else

			err = 0;

		break;

	default:

		err = 0;

	}

	if (err)

		goto out;



	CIO_MSG_EVENT(4, "Subchannel 0.%x.%04x reports subchannel type %04X\n",

		      schid.ssid, schid.sch_no, schib->pmcw.st);

out:

	return err;

}



/*

 * do_cio_interrupt() handles all normal I/O device IRQ's

 */
@@ -707,6 +649,7 @@ struct subchannel *cio_probe_console(void) 
{

	struct subchannel_id schid;

	struct subchannel *sch;

	struct schib schib;

	int sch_no, ret;



	sch_no = cio_get_console_sch_no();
@@ -716,7 +659,11 @@ struct subchannel *cio_probe_console(void) 
	}

	init_subchannel_id(&schid);

	schid.sch_no = sch_no;

	sch = css_alloc_subchannel(schid);

	ret = stsch(schid, &schib);

	if (ret)

		return ERR_PTR(-ENODEV);



	sch = css_alloc_subchannel(schid, &schib);

	if (IS_ERR(sch))

		return sch;

drivers/s390/cio/cio.h

+0 −1
Original line number Diff line number Diff line
@@ -119,7 +119,6 @@ DECLARE_PER_CPU(struct irb, cio_irb); 


#define to_subchannel(n) container_of(n, struct subchannel, dev)



extern int cio_validate_subchannel(struct subchannel_id, struct schib *);

extern int cio_enable_subchannel(struct subchannel *, u32);

extern int cio_disable_subchannel (struct subchannel *);

extern int cio_cancel (struct subchannel *);

drivers/s390/cio/css.c

+49 −18
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 


#include "css.h"

#include "cio.h"

#include "blacklist.h"

#include "cio_debug.h"

#include "ioasm.h"

#include "chsc.h"
@@ -168,13 +169,43 @@ static void css_subchannel_release(struct device *dev) 
	kfree(sch);

}



struct subchannel *css_alloc_subchannel(struct subchannel_id schid)

static int css_validate_subchannel(struct subchannel_id schid,

				   struct schib *schib)

{

	int err;



	switch (schib->pmcw.st) {

	case SUBCHANNEL_TYPE_IO:

	case SUBCHANNEL_TYPE_MSG:

		if (!css_sch_is_valid(schib))

			err = -ENODEV;

		else if (is_blacklisted(schid.ssid, schib->pmcw.dev)) {

			CIO_MSG_EVENT(6, "Blacklisted device detected "

				      "at devno %04X, subchannel set %x\n",

				      schib->pmcw.dev, schid.ssid);

			err = -ENODEV;

		} else

			err = 0;

		break;

	default:

		err = 0;

	}

	if (err)

		goto out;



	CIO_MSG_EVENT(4, "Subchannel 0.%x.%04x reports subchannel type %04X\n",

		      schid.ssid, schid.sch_no, schib->pmcw.st);

out:

	return err;

}



struct subchannel *css_alloc_subchannel(struct subchannel_id schid,

					struct schib *schib)

{

	struct subchannel *sch;

	struct schib schib;

	int ret;



	ret = cio_validate_subchannel(schid, &schib);

	ret = css_validate_subchannel(schid, schib);

	if (ret < 0)

		return ERR_PTR(ret);
@@ -183,8 +214,8 @@ struct subchannel *css_alloc_subchannel(struct subchannel_id schid) 
		return ERR_PTR(-ENOMEM);



	sch->schid = schid;

	sch->schib = schib;

	sch->st = schib.pmcw.st;

	sch->schib = *schib;

	sch->st = schib->pmcw.st;



	ret = css_sch_create_locks(sch);

	if (ret)
@@ -386,12 +417,12 @@ int css_register_subchannel(struct subchannel *sch) 
	return ret;

}



static int css_probe_device(struct subchannel_id schid)

static int css_probe_device(struct subchannel_id schid, struct schib *schib)

{

	struct subchannel *sch;

	int ret;



	sch = css_alloc_subchannel(schid);

	sch = css_alloc_subchannel(schid, schib);

	if (IS_ERR(sch))

		return PTR_ERR(sch);
@@ -440,23 +471,23 @@ EXPORT_SYMBOL_GPL(css_sch_is_valid); 
static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)

{

	struct schib schib;

	int ccode;



	if (!slow) {

		/* Will be done on the slow path. */

		return -EAGAIN;

	}

	if (stsch(schid, &schib)) {

		/* Subchannel is not provided. */

		return -ENXIO;

	}

	if (!css_sch_is_valid(&schib)) {

		/* Unusable - ignore. */

		return 0;

	}

	CIO_MSG_EVENT(4, "event: sch 0.%x.%04x, new\n", schid.ssid,

		      schid.sch_no);

	/*

	 * The first subchannel that is not-operational (ccode==3)

	 * indicates that there aren't any more devices available.

	 * If stsch gets an exception, it means the current subchannel set

	 * is not valid.

	 */

	ccode = stsch(schid, &schib);

	if (ccode)

		return (ccode == 3) ? -ENXIO : ccode;



	return css_probe_device(schid);

	return css_probe_device(schid, &schib);

}



static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)

drivers/s390/cio/css.h

+2 −1
Original line number Diff line number Diff line
@@ -103,7 +103,8 @@ extern void css_driver_unregister(struct css_driver *); 


extern void css_sch_device_unregister(struct subchannel *);

extern int css_register_subchannel(struct subchannel *);

extern struct subchannel *css_alloc_subchannel(struct subchannel_id);

extern struct subchannel *css_alloc_subchannel(struct subchannel_id,

					       struct schib *schib);

extern struct subchannel *get_subchannel_by_schid(struct subchannel_id);

extern int css_init_done;

extern int max_ssid;