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[S390] cio: Fix reference counting for online/offline.

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The current code attempts to get an extra reference count
for online devices by doing a get_device() in ccw_device_online()
and a put_device() in ccw_device_done(). However, this
- incorrectly obtains an extra reference for disconnected
  devices becoming available again (since they are already
  online)
- needs special checks for css_init_done in order to handle
  the console device
- is not obvious and
- may incorretly drop a reference count in ccw_device_done() if
  that function is called after path verification for a device
  that just became not operational.

So let's just get the reference in ccw_device_set_online() and
drop it in ccw_device_set_offline(). (Unfortunately, we still
need the special case in io_subchannel_probe().)

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Cornelia Huck 2008-12-25 13:39:06 +01:00 committed by Martin Schwidefsky
parent 97166f52fc
commit 9cd6742197
2 changed files with 22 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/s390/cio/device.c
View File

@ -376,19 +376,23 @@ int ccw_device_set_offline(struct ccw_device *cdev)
dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
}
spin_unlock_irq(cdev->ccwlock);
/* Give up reference from ccw_device_set_online(). */
put_device(&cdev->dev);
return ret;
}
spin_unlock_irq(cdev->ccwlock);
if (ret == 0)
if (ret == 0) {
wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
else {
/* Give up reference from ccw_device_set_online(). */
put_device(&cdev->dev);
} else {
CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "
"device 0.%x.%04x\n",
ret, cdev->private->dev_id.ssid,
cdev->private->dev_id.devno);
cdev->online = 1;
}
return ret;
return ret;
}
/**
@ -411,6 +415,9 @@ int ccw_device_set_online(struct ccw_device *cdev)
return -ENODEV;
if (cdev->online || !cdev->drv)
return -EINVAL;
/* Hold on to an extra reference while device is online. */
if (!get_device(&cdev->dev))
return -ENODEV;
spin_lock_irq(cdev->ccwlock);
ret = ccw_device_online(cdev);
@ -422,10 +429,15 @@ int ccw_device_set_online(struct ccw_device *cdev)
"device 0.%x.%04x\n",
ret, cdev->private->dev_id.ssid,
cdev->private->dev_id.devno);
/* Give up online reference since onlining failed. */
put_device(&cdev->dev);
return ret;
}
if (cdev->private->state != DEV_STATE_ONLINE)
if (cdev->private->state != DEV_STATE_ONLINE) {
/* Give up online reference since onlining failed. */
put_device(&cdev->dev);
return -ENODEV;
}
if (!cdev->drv->set_online || cdev->drv->set_online(cdev) == 0) {
cdev->online = 1;
return 0;
@ -440,6 +452,8 @@ int ccw_device_set_online(struct ccw_device *cdev)
"device 0.%x.%04x\n",
ret, cdev->private->dev_id.ssid,
cdev->private->dev_id.devno);
/* Give up online reference since onlining failed. */
put_device(&cdev->dev);
return (ret == 0) ? -ENODEV : ret;
}
@ -1168,9 +1182,8 @@ static int io_subchannel_probe(struct subchannel *sch)
ccw_device_register(cdev);
/*
* Check if the device is already online. If it is
* the reference count needs to be corrected
* (see ccw_device_online and css_init_done for the
* ugly details).
* the reference count needs to be corrected since we
* didn't obtain a reference in ccw_device_set_online.
*/
if (cdev->private->state != DEV_STATE_NOT_OPER &&
cdev->private->state != DEV_STATE_OFFLINE &&
@ -1806,6 +1819,8 @@ ccw_device_remove (struct device *dev)
"device 0.%x.%04x\n",
ret, cdev->private->dev_id.ssid,
cdev->private->dev_id.devno);
/* Give up reference obtained in ccw_device_set_online(). */
put_device(&cdev->dev);
}
ccw_device_set_timeout(cdev, 0);
cdev->drv = NULL;

5
drivers/s390/cio/device_fsm.c
View File

@ -399,9 +399,6 @@ ccw_device_done(struct ccw_device *cdev, int state)
ccw_device_oper_notify(cdev);
}
wake_up(&cdev->private->wait_q);
if (css_init_done && state != DEV_STATE_ONLINE)
put_device (&cdev->dev);
}
static int cmp_pgid(struct pgid *p1, struct pgid *p2)
@ -611,8 +608,6 @@ ccw_device_online(struct ccw_device *cdev)
(cdev->private->state != DEV_STATE_BOXED))
return -EINVAL;
sch = to_subchannel(cdev->dev.parent);
if (css_init_done && !get_device(&cdev->dev))
return -ENODEV;
ret = cio_enable_subchannel(sch, (u32)(addr_t)sch);
if (ret != 0) {
/* Couldn't enable the subchannel for i/o. Sick device. */