Re: [RFCv2 02/20] Bluetooth: Process HCI callbacks in a workqueue

On Tuesday 24 July 2012 16:46:41 Andrei Emeltchenko wrote:

Hi Oliver,

On Tue, Jul 24, 2012 at 03:31:37PM +0200, Oliver Neukum wrote:

quoted

On Tuesday 24 July 2012 16:21:43 Andrei Emeltchenko wrote:

quoted

+void hci_queue_cb(struct hci_dev *hdev, struct hci_cb_cmd *cmd,
+                 struct workqueue_struct *workqueue)
+{
+       struct hci_cb_work *work;
+
+       BT_DBG("%s queue cmd %p", hdev->name, cmd);
+
+       work = kmalloc(sizeof(*work), GFP_KERNEL);

This looks like prone to deadlocks. You can run networked file
systems over the link and allocating memory with GFP_KERNEL
could run into a recursion problem.

Sorry, how this might run into recursion problem?

Suppose you transfer something necessary for writing out a dirty
page over the HCI and you call hci_queue_cb() to do so. Then
GFP_KERNEL causes another page to be written out over the same path.
(eg. NFS over PAN)

	Regards
		Oliver