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authorCornelia Huck <cornelia.huck@de.ibm.com>2008-12-25 13:39:06 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-12-25 13:39:07 +0100
commit9cd67421977a701272820987ff9e6f197b1b97b7 (patch)
tree3d29b739749d6aeb0d3f427b23678d71d080c307
parent97166f52fc84c0bc49c7dbba2a26720110acb458 (diff)
[S390] cio: Fix reference counting for online/offline.
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>
-rw-r--r--drivers/s390/cio/device.c29
-rw-r--r--drivers/s390/cio/device_fsm.c5
2 files changed, 22 insertions, 12 deletions
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 647cbaca298..039ef03cf21 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -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;
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index 10bc03940fb..01330cf5ae5 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -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. */