I think you're rignt.
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>
(2012/04/08 3:18), Jiang Liu wrote:
> When destroying a PCIe hotplug controller, all work items associated with
> that controller should be flushed. Function pcie_cleanup_slot() calls
> cancel_delayed_work() and flush_workqueue() to achieve that.
> Function flush_workqueue() will flush all work items already submitted,
> but new work items submitted by those already submitted work items may
> still be in live state when returning from flush_workqueue().
>
> For the extreme case, pciehp driver may expierence following calling path:
> 1) pcie_isr() -> pciehp_handle_xxx() -> queue_interrupt_event()->queue_work()
> 2) interrupt_event_handler() -> handle_button_press_event() ->
> queue_delayed_work()
> 3) pciehp_queue_pushbutton_work() -> queue_work()
>
> So enhance pcie_cleanup_slot() to correctly flush workqueue when destroying
> PCIe hotplug controller.
>
> Signed-off-by: Jiang Liu<jiang.liu@xxxxxxxxxx>
> ---
> drivers/pci/hotplug/pciehp_hpc.c | 13 ++++++++++++-
> 1 files changed, 12 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index d4fa705..9a48a51 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -890,8 +890,19 @@ static int pcie_init_slot(struct controller *ctrl)
> static void pcie_cleanup_slot(struct controller *ctrl)
> {
> struct slot *slot = ctrl->slot;
> - cancel_delayed_work(&slot->work);
> +
> + /*
> + * Following workqueue flushing logic is to deal with the special call path:
> + * 1) pcie_isr() -> pciehp_handle_xxx() ->
> + * queue_interrupt_event(pciehp_wq_event)->queue_work(pciehp_wq)
> + * 2) interrupt_event_handler() -> handle_button_press_event() ->
> + * queue_delayed_work(pciehp_wq)
> + * 3) pciehp_queue_pushbutton_work() -> queue_work(pciehp_wq)
> + */
> flush_workqueue(pciehp_wq);
> + cancel_delayed_work_sync(&slot->work);
> + flush_workqueue(pciehp_wq);
> +
> kfree(slot);
> }
>
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