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authorCornelia Huck <cornelia.huck@de.ibm.com>2008-12-25 13:39:08 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-12-25 13:39:08 +0100
commit5fb6b8544d9ccd2ed478af777f9e99e342eb8886 (patch)
tree21d3819588970ea7e0421d79df088332fcadbb17 /drivers
parent6eff208f479d6fe99fd92c0e6bf7e930bb45cd30 (diff)
[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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/s390/cio/device.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index cba33aa1df79..91acea10840d 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -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);
}