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[S390] cio: Avoid machine check vs. not operational races.
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There was the possibilty that an action like ccw_device_set_offline()
triggered by a device gone machine check might trigger a not oper
event. Unfortunately, this could lead to the situation that we tried
to unregister a subchannel twice: Once from the slow path evaluation,
and once via the not oper event.

Fix this by always using the same mechanism (css_schedule_eval()) for
triggering the unregister. This makes sure that unregistration will
only be done once. As an added bonus, it also simplyfies the code.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Cornelia Huck authored and Martin Schwidefsky committed Oct 12, 2007
1 parent 3952c8d commit 3f4cf6e
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Showing 3 changed files with 21 additions and 127 deletions.
3 changes: 1 addition & 2 deletions drivers/s390/cio/device.c
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Original file line number Diff line number Diff line change
Expand Up @@ -969,8 +969,7 @@ io_subchannel_register(struct work_struct *work)
wake_up(&ccw_device_init_wq);
}

void
ccw_device_call_sch_unregister(struct work_struct *work)
static void ccw_device_call_sch_unregister(struct work_struct *work)
{
struct ccw_device_private *priv;
struct ccw_device *cdev;
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1 change: 0 additions & 1 deletion drivers/s390/cio/device.h
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,6 @@ void io_subchannel_recog_done(struct ccw_device *cdev);
int ccw_device_cancel_halt_clear(struct ccw_device *);

void ccw_device_do_unreg_rereg(struct work_struct *);
void ccw_device_call_sch_unregister(struct work_struct *);
void ccw_device_move_to_orphanage(struct work_struct *);
int ccw_device_is_orphan(struct ccw_device *);

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144 changes: 20 additions & 124 deletions drivers/s390/cio/device_fsm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -544,51 +544,6 @@ ccw_device_recog_timeout(struct ccw_device *cdev, enum dev_event dev_event)
}


static void
ccw_device_nopath_notify(struct work_struct *work)
{
struct ccw_device_private *priv;
struct ccw_device *cdev;
struct subchannel *sch;
int ret;
unsigned long flags;

priv = container_of(work, struct ccw_device_private, kick_work);
cdev = priv->cdev;
spin_lock_irqsave(cdev->ccwlock, flags);
sch = to_subchannel(cdev->dev.parent);
/* Extra sanity. */
if (sch->lpm)
goto out_unlock;
if (sch->driver && sch->driver->notify) {
spin_unlock_irqrestore(cdev->ccwlock, flags);
ret = sch->driver->notify(&sch->dev, CIO_NO_PATH);
spin_lock_irqsave(cdev->ccwlock, flags);
} else
ret = 0;
if (!ret) {
if (get_device(&sch->dev)) {
/* Driver doesn't want to keep device. */
cio_disable_subchannel(sch);
if (get_device(&cdev->dev)) {
PREPARE_WORK(&cdev->private->kick_work,
ccw_device_call_sch_unregister);
queue_work(ccw_device_work,
&cdev->private->kick_work);
} else
put_device(&sch->dev);
}
} else {
cio_disable_subchannel(sch);
ccw_device_set_timeout(cdev, 0);
cdev->private->flags.fake_irb = 0;
cdev->private->state = DEV_STATE_DISCONNECTED;
wake_up(&cdev->private->wait_q);
}
out_unlock:
spin_unlock_irqrestore(cdev->ccwlock, flags);
}

void
ccw_device_verify_done(struct ccw_device *cdev, int err)
{
Expand Down Expand Up @@ -632,12 +587,9 @@ ccw_device_verify_done(struct ccw_device *cdev, int err)
default:
/* Reset oper notify indication after verify error. */
cdev->private->flags.donotify = 0;
if (cdev->online) {
PREPARE_WORK(&cdev->private->kick_work,
ccw_device_nopath_notify);
queue_work(ccw_device_notify_work,
&cdev->private->kick_work);
} else
if (cdev->online)
dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
else
ccw_device_done(cdev, DEV_STATE_NOT_OPER);
break;
}
Expand Down Expand Up @@ -691,11 +643,7 @@ ccw_device_disband_done(struct ccw_device *cdev, int err)
break;
default:
cdev->private->flags.donotify = 0;
if (get_device(&cdev->dev)) {
PREPARE_WORK(&cdev->private->kick_work,
ccw_device_call_sch_unregister);
queue_work(ccw_device_work, &cdev->private->kick_work);
}
dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
ccw_device_done(cdev, DEV_STATE_NOT_OPER);
break;
}
Expand Down Expand Up @@ -766,59 +714,16 @@ ccw_device_recog_notoper(struct ccw_device *cdev, enum dev_event dev_event)
}

/*
* Handle not operational event while offline.
* Handle not operational event in non-special state.
*/
static void
ccw_device_offline_notoper(struct ccw_device *cdev, enum dev_event dev_event)
static void ccw_device_generic_notoper(struct ccw_device *cdev,
enum dev_event dev_event)
{
struct subchannel *sch;

cdev->private->state = DEV_STATE_NOT_OPER;
sch = to_subchannel(cdev->dev.parent);
if (get_device(&cdev->dev)) {
PREPARE_WORK(&cdev->private->kick_work,
ccw_device_call_sch_unregister);
queue_work(ccw_device_work, &cdev->private->kick_work);
}
wake_up(&cdev->private->wait_q);
}

/*
* Handle not operational event while online.
*/
static void
ccw_device_online_notoper(struct ccw_device *cdev, enum dev_event dev_event)
{
struct subchannel *sch;
int ret;

sch = to_subchannel(cdev->dev.parent);
if (sch->driver->notify) {
spin_unlock_irq(cdev->ccwlock);
ret = sch->driver->notify(&sch->dev,
sch->lpm ? CIO_GONE : CIO_NO_PATH);
spin_lock_irq(cdev->ccwlock);
} else
ret = 0;
if (ret) {
ccw_device_set_timeout(cdev, 0);
cdev->private->flags.fake_irb = 0;
cdev->private->state = DEV_STATE_DISCONNECTED;
wake_up(&cdev->private->wait_q);
return;
}
cdev->private->state = DEV_STATE_NOT_OPER;
cio_disable_subchannel(sch);
if (sch->schib.scsw.actl != 0) {
// FIXME: not-oper indication to device driver ?
ccw_device_call_handler(cdev);
}
if (get_device(&cdev->dev)) {
PREPARE_WORK(&cdev->private->kick_work,
ccw_device_call_sch_unregister);
queue_work(ccw_device_work, &cdev->private->kick_work);
}
wake_up(&cdev->private->wait_q);
css_schedule_eval(sch->schid);
}

/*
Expand Down Expand Up @@ -916,18 +821,9 @@ ccw_device_online_timeout(struct ccw_device *cdev, enum dev_event dev_event)
cdev->private->state = DEV_STATE_TIMEOUT_KILL;
return;
}
if (ret == -ENODEV) {
struct subchannel *sch;

sch = to_subchannel(cdev->dev.parent);
if (!sch->lpm) {
PREPARE_WORK(&cdev->private->kick_work,
ccw_device_nopath_notify);
queue_work(ccw_device_notify_work,
&cdev->private->kick_work);
} else
dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
} else if (cdev->handler)
if (ret == -ENODEV)
dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
else if (cdev->handler)
cdev->handler(cdev, cdev->private->intparm,
ERR_PTR(-ETIMEDOUT));
}
Expand Down Expand Up @@ -1234,7 +1130,7 @@ fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
[DEV_EVENT_VERIFY] = ccw_device_nop,
},
[DEV_STATE_SENSE_PGID] = {
[DEV_EVENT_NOTOPER] = ccw_device_online_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_sense_pgid_irq,
[DEV_EVENT_TIMEOUT] = ccw_device_onoff_timeout,
[DEV_EVENT_VERIFY] = ccw_device_nop,
Expand All @@ -1246,50 +1142,50 @@ fsm_func_t *dev_jumptable[NR_DEV_STATES][NR_DEV_EVENTS] = {
[DEV_EVENT_VERIFY] = ccw_device_nop,
},
[DEV_STATE_OFFLINE] = {
[DEV_EVENT_NOTOPER] = ccw_device_offline_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_offline_irq,
[DEV_EVENT_TIMEOUT] = ccw_device_nop,
[DEV_EVENT_VERIFY] = ccw_device_nop,
},
[DEV_STATE_VERIFY] = {
[DEV_EVENT_NOTOPER] = ccw_device_online_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_verify_irq,
[DEV_EVENT_TIMEOUT] = ccw_device_onoff_timeout,
[DEV_EVENT_VERIFY] = ccw_device_delay_verify,
},
[DEV_STATE_ONLINE] = {
[DEV_EVENT_NOTOPER] = ccw_device_online_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_irq,
[DEV_EVENT_TIMEOUT] = ccw_device_online_timeout,
[DEV_EVENT_VERIFY] = ccw_device_online_verify,
},
[DEV_STATE_W4SENSE] = {
[DEV_EVENT_NOTOPER] = ccw_device_online_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_w4sense,
[DEV_EVENT_TIMEOUT] = ccw_device_nop,
[DEV_EVENT_VERIFY] = ccw_device_online_verify,
},
[DEV_STATE_DISBAND_PGID] = {
[DEV_EVENT_NOTOPER] = ccw_device_online_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_disband_irq,
[DEV_EVENT_TIMEOUT] = ccw_device_onoff_timeout,
[DEV_EVENT_VERIFY] = ccw_device_nop,
},
[DEV_STATE_BOXED] = {
[DEV_EVENT_NOTOPER] = ccw_device_offline_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_stlck_done,
[DEV_EVENT_TIMEOUT] = ccw_device_stlck_done,
[DEV_EVENT_VERIFY] = ccw_device_nop,
},
/* states to wait for i/o completion before doing something */
[DEV_STATE_CLEAR_VERIFY] = {
[DEV_EVENT_NOTOPER] = ccw_device_online_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_clear_verify,
[DEV_EVENT_TIMEOUT] = ccw_device_nop,
[DEV_EVENT_VERIFY] = ccw_device_nop,
},
[DEV_STATE_TIMEOUT_KILL] = {
[DEV_EVENT_NOTOPER] = ccw_device_online_notoper,
[DEV_EVENT_NOTOPER] = ccw_device_generic_notoper,
[DEV_EVENT_INTERRUPT] = ccw_device_killing_irq,
[DEV_EVENT_TIMEOUT] = ccw_device_killing_timeout,
[DEV_EVENT_VERIFY] = ccw_device_nop, //FIXME
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