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[S390] cio: introduce subchannel todos

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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: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Peter Oberparleiter 2009-12-07 12:51:18 +01:00 committed by Martin Schwidefsky
parent 5d6e6b6f6f
commit 390935acac
4 changed files with 63 additions and 19 deletions
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8
drivers/s390/cio/cio.h
View File

@ -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)));

48
drivers/s390/cio/css.c
View File

@ -133,6 +133,8 @@ out:
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;

3
drivers/s390/cio/css.h
View File

@ -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

23
drivers/s390/cio/device.c
View File

@ -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,