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ieee1394: raw1394: prevent unloading of low-level driver

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Unloading the low-level driver module of a FireWire host can lead to
all sorts of trouble if a raw1394 userspace client is using the host.
Just disallow it by incrementing the LLD's module reference count on
a RAW1394_REQ_SET_CARD write operation.  Decrement it when the file
is closed.

This feature wouldn't be relevant if "modprobe -r video1394" or
"modprobe -r dv1394" didn't automatically unload ohci1394 too.
http://bugzilla.kernel.org/show_bug.cgi?id=7701

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Dan Dennedy <dan@dennedy.org>
This commit is contained in:
Stefan Richter 2007-02-03 16:48:51 +01:00
parent 12ba145c94
commit 0fe4c6fcac
1 changed files with 29 additions and 19 deletions
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48
drivers/ieee1394/raw1394.c
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@ -636,27 +636,32 @@ static int state_initialized(struct file_info *fi, struct pending_request *req)
case RAW1394_REQ_SET_CARD:
spin_lock_irqsave(&host_info_lock, flags);
if (req->req.misc < host_count) {
list_for_each_entry(hi, &host_info_list, list) {
if (!req->req.misc--)
break;
}
get_device(&hi->host->device); // XXX Need to handle failure case
list_add_tail(&fi->list, &hi->file_info_list);
fi->host = hi->host;
fi->state = connected;
req->req.error = RAW1394_ERROR_NONE;
req->req.generation = get_hpsb_generation(fi->host);
req->req.misc = (fi->host->node_id << 16)
| fi->host->node_count;
if (fi->protocol_version > 3) {
req->req.misc |=
NODEID_TO_NODE(fi->host->irm_id) << 8;
}
} else {
if (req->req.misc >= host_count) {
req->req.error = RAW1394_ERROR_INVALID_ARG;
goto out_set_card;
}
list_for_each_entry(hi, &host_info_list, list)
if (!req->req.misc--)
break;
get_device(&hi->host->device); /* FIXME handle failure case */
list_add_tail(&fi->list, &hi->file_info_list);
/* prevent unloading of the host's low-level driver */
if (!try_module_get(hi->host->driver->owner)) {
req->req.error = RAW1394_ERROR_ABORTED;
goto out_set_card;
}
WARN_ON(fi->host);
fi->host = hi->host;
fi->state = connected;
req->req.error = RAW1394_ERROR_NONE;
req->req.generation = get_hpsb_generation(fi->host);
req->req.misc = (fi->host->node_id << 16)
| fi->host->node_count;
if (fi->protocol_version > 3)
req->req.misc |= NODEID_TO_NODE(fi->host->irm_id) << 8;
out_set_card:
spin_unlock_irqrestore(&host_info_lock, flags);
req->req.length = 0;
@ -2955,6 +2960,11 @@ static int raw1394_release(struct inode *inode, struct file *file)
put_device(&fi->host->device);
}
spin_lock_irqsave(&host_info_lock, flags);
if (fi->host)
module_put(fi->host->driver->owner);
spin_unlock_irqrestore(&host_info_lock, flags);
kfree(fi);
return 0;