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[S390] cio: Only register ccw_device for registered subchannel. 

There is a race between io_subchannel_register() and
io_subchannel_sch_event() which may cause a subchannel to be
unregistered because it is no longer operational before
io_subchannel_register() had run. We need to check whether the
subchannel is still registered before the ccw device can be
registered and just bail out if it is not.

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 13:39:08 +01:00 committed by Martin Schwidefsky
parent 6eff208f47
commit 5fb6b8544d
1 changed files with 12 additions and 6 deletions
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18
drivers/s390/cio/device.c
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@ -950,6 +950,14 @@ io_subchannel_register(struct work_struct *work)
priv = container_of(work, struct ccw_device_private, kick_work);
cdev = priv->cdev;
sch = to_subchannel(cdev->dev.parent);
/*
* Check if subchannel is still registered. It may have become
* unregistered if a machine check hit us after finishing
* device recognition but before the register work could be
* queued.
*/
if (!device_is_registered(&sch->dev))
goto out_err;
css_update_ssd_info(sch);
/*
* io_subchannel_register() will also be called after device
@ -984,18 +992,16 @@ io_subchannel_register(struct work_struct *work)
spin_lock_irqsave(sch->lock, flags);
sch_set_cdev(sch, NULL);
spin_unlock_irqrestore(sch->lock, flags);
/* Release reference for workqueue processing. */
put_device(&cdev->dev);
/* Release initial device reference. */
put_device(&cdev->dev);
if (atomic_dec_and_test(&ccw_device_init_count))
wake_up(&ccw_device_init_wq);
return;
goto out_err;
}
put_device(&cdev->dev);
out:
cdev->private->flags.recog_done = 1;
wake_up(&cdev->private->wait_q);
out_err:
/* Release reference for workqueue processing. */
put_device(&cdev->dev);
if (atomic_dec_and_test(&ccw_device_init_count))
wake_up(&ccw_device_init_wq);
}