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Commit 390935ac authored by Peter Oberparleiter's avatar Peter Oberparleiter Committed by Martin Schwidefsky
Browse files

[S390] cio: introduce subchannel todos 



Ensure that current and future users of sch->work do not overwrite
each other by introducing a single mechanism for delayed subchannel
work.

Signed-off-by: default avatarPeter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 5d6e6b6f

drivers/s390/cio/cio.h

+7 −1
Original line number Diff line number Diff line
@@ -68,6 +68,11 @@ struct schib { 
	__u8 mda[4];		 /* model dependent area */

} __attribute__ ((packed,aligned(4)));



enum sch_todo {

	SCH_TODO_NOTHING,

	SCH_TODO_UNREG,

};



/* subchannel data structure used by I/O subroutines */

struct subchannel {

	struct subchannel_id schid;
@@ -95,7 +100,8 @@ struct subchannel { 
	struct device dev;	/* entry in device tree */

	struct css_driver *driver;

	void *private; /* private per subchannel type data */

	struct work_struct work;

	enum sch_todo todo;

	struct work_struct todo_work;

	struct schib_config config;

} __attribute__ ((aligned(8)));

drivers/s390/cio/css.c

+48 −0
Original line number Diff line number Diff line
@@ -133,6 +133,8 @@ int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *), 
	return rc;

}



static void css_sch_todo(struct work_struct *work);



static struct subchannel *

css_alloc_subchannel(struct subchannel_id schid)

{
@@ -147,6 +149,7 @@ css_alloc_subchannel(struct subchannel_id schid) 
		kfree(sch);

		return ERR_PTR(ret);

	}

	INIT_WORK(&sch->todo_work, css_sch_todo);

	return sch;

}
@@ -190,6 +193,51 @@ void css_sch_device_unregister(struct subchannel *sch) 
}

EXPORT_SYMBOL_GPL(css_sch_device_unregister);



static void css_sch_todo(struct work_struct *work)

{

	struct subchannel *sch;

	enum sch_todo todo;



	sch = container_of(work, struct subchannel, todo_work);

	/* Find out todo. */

	spin_lock_irq(sch->lock);

	todo = sch->todo;

	CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid,

		      sch->schid.sch_no, todo);

	sch->todo = SCH_TODO_NOTHING;

	spin_unlock_irq(sch->lock);

	/* Perform todo. */

	if (todo == SCH_TODO_UNREG)

		css_sch_device_unregister(sch);

	/* Release workqueue ref. */

	put_device(&sch->dev);

}



/**

 * css_sched_sch_todo - schedule a subchannel operation

 * @sch: subchannel

 * @todo: todo

 *

 * Schedule the operation identified by @todo to be performed on the slow path

 * workqueue. Do nothing if another operation with higher priority is already

 * scheduled. Needs to be called with subchannel lock held.

 */

void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo)

{

	CIO_MSG_EVENT(4, "sch_todo: sched sch=0.%x.%04x todo=%d\n",

		      sch->schid.ssid, sch->schid.sch_no, todo);

	if (sch->todo >= todo)

		return;

	/* Get workqueue ref. */

	if (!get_device(&sch->dev))

		return;

	sch->todo = todo;

	if (!queue_work(slow_path_wq, &sch->todo_work)) {

		/* Already queued, release workqueue ref. */

		put_device(&sch->dev);

	}

}



static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)

{

	int i;

drivers/s390/cio/css.h

+3 −0
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ 
#include <asm/chpid.h>

#include <asm/schid.h>



#include "cio.h"



/*

 * path grouping stuff

 */
@@ -151,4 +153,5 @@ int css_sch_is_valid(struct schib *); 


extern struct workqueue_struct *slow_path_wq;

void css_wait_for_slow_path(void);

void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo);

#endif

drivers/s390/cio/device.c

+5 −18
Original line number Diff line number Diff line
@@ -1051,23 +1051,6 @@ static void io_subchannel_init_fields(struct subchannel *sch) 
	io_subchannel_init_config(sch);

}



static void io_subchannel_do_unreg(struct work_struct *work)

{

	struct subchannel *sch;



	sch = container_of(work, struct subchannel, work);

	css_sch_device_unregister(sch);

	put_device(&sch->dev);

}



/* Schedule unregister if we have no cdev. */

static void io_subchannel_schedule_removal(struct subchannel *sch)

{

	get_device(&sch->dev);

	INIT_WORK(&sch->work, io_subchannel_do_unreg);

	queue_work(slow_path_wq, &sch->work);

}



/*

 * Note: We always return 0 so that we bind to the device even on error.

 * This is needed so that our remove function is called on unregister.
@@ -1124,7 +1107,9 @@ static int io_subchannel_probe(struct subchannel *sch) 
	return 0;



out_schedule:

	io_subchannel_schedule_removal(sch);

	spin_lock_irq(sch->lock);

	css_sched_sch_todo(sch, SCH_TODO_UNREG);

	spin_unlock_irq(sch->lock);

	return 0;

}
@@ -1469,6 +1454,8 @@ static int io_subchannel_sch_event(struct subchannel *sch, int process) 
	spin_lock_irqsave(sch->lock, flags);

	if (!device_is_registered(&sch->dev))

		goto out_unlock;

	if (work_pending(&sch->todo_work))

		goto out_unlock;

	action = sch_get_action(sch);

	CIO_MSG_EVENT(2, "event: sch 0.%x.%04x, process=%d, action=%d\n",

		      sch->schid.ssid, sch->schid.sch_no, process,