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    SubjectRe: [PATCH] usb: add Freescale QE/CPM USB peripheral controller driver
    On Thu, Aug 28, 2008 at 05:43:33PM +0800, Li Yang wrote:
    > Some of Freescale SoC chips have a QE or CPM co-processor which
    > supports full speed USB. The driver adds device mode support
    > of both QE and CPM USB controller to Linux USB gadget. The
    > driver is tested with MPC8360 and MPC8272, and should work with
    > other models having QE/CPM given minor tweaks.
    >
    > Signed-off-by: Xie Xiaobo <X.Xie@freescale.com>
    > Signed-off-by: Li Yang <leoli@freescale.com>
    > ---

    Just found a recursive locking bug:

    [...]
    > +static int reset_queues(struct qe_udc *udc)
    > +{

    Note: this function is called from the IRQ, the IRQ handler
    grabs udc->lock spinlock..

    > + u8 pipe;
    > +
    > + for (pipe = 0; pipe < USB_MAX_ENDPOINTS; pipe++)
    > + udc_reset_ep_queue(udc, pipe);
    > +
    > + /* report disconnect; the driver is already quiesced */
    > + udc->driver->disconnect(&udc->gadget);

    In the disconnect(), g_ether driver will immediately call
    qe_ep_disable() function which will try to grab &udc->lock
    spinlock once again..

    Not sure how to fix this properly... :-/

    p.s. the same bug exists in omap_udc.c, pxa27x_udc.c and probably
    other drivers as well... The only reason why it does not exploit
    in most cases is that the spin_lock_irqsave for !SMP case turns
    into simple local_irq_save().

    --
    Anton Vorontsov
    email: cbouatmailru@gmail.com
    irc://irc.freenode.net/bd2


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