Messages in this thread | | | Date | Wed, 23 Jan 2008 18:38:22 +0000 | From | Ian Abbott <> | Subject | Re: [RESEND][PATCH-2.6.24-rc8] Fix fakephp deadlock |
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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@mev.co.uk> )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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