On Wed, Jan 23, 2008 at 06:38:22PM +0000, Ian Abbott wrote:
> 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?
Heh, an unsigned long as a boolean? Come on... :)
>> 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.
That sounds reasonable.
thanks,
greg k-h
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