Re: [RESEND][PATCH-2.6.24-rc8] Fix fakephp deadlock
From: Ian Abbott
Date: Wed Jan 23 2008 - 13:38:41 EST
On 23/01/08 17:46, Greg KH wrote:
On Tue, Jan 22, 2008 at 02:28:08PM +0000, Ian Abbott wrote:
#include <linux/init.h>
#include <linux/string.h>
#include <linux/slab.h>
+#include <linux/workqueue.h>
#include "../pci.h"
#if !defined(MODULE)
@@ -63,10 +64,13 @@ struct dummy_slot {
struct list_head node;
struct hotplug_slot *slot;
struct pci_dev *dev;
+ struct work_struct remove_work;
+ unsigned long removed;
You are treating "removed" as an atomic value, so why not just make it
an atomic_t?
Because I'm using it as a boolean?
And what is protecting the fact that the flag could be set right after
it gets checked? I don't see a lock here :)
Okay, it looks like there might be a race condition between
enable_slot() and disable_slot() if some other task calls disable_slot()
while enable_slot() is between the test_bit() and flush_workqueue()
calls. I can fix that by avoiding the call to flush_workqueue() in
enable_slot() and allocating and queueing a work queue item to defer the
call to pci_rescan(). And enable_slot() won't then need to check if the
slot was marked as removed - it can just go ahead and allocate and queue
a work item.
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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