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SubjectRe: [PATCH] usbhid: Fix lockdep unannotated irqs-off warning
On Sat, 5 Mar 2016, Sedat Dilek wrote:

> On Fri, Mar 4, 2016 at 5:04 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > On Wed, 2 Mar 2016, Sedat Dilek wrote:
> >
> >> On 3/1/16, Alan Stern <stern@rowland.harvard.edu> wrote:
> >> > On Tue, 1 Mar 2016, Sedat Dilek wrote:
> >> >
> >> >> On Tue, Oct 13, 2015 at 2:57 AM, Steven Rostedt <rostedt@goodmis.org>
> >> >> wrote:
> >> >> > On Sat, 3 Oct 2015 12:05:42 +0200
> >> >> > Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >> >> >
> >> >> >> So, at the beginning... dunno WTF is causing the problems - no
> >> >> >> workaround for CLANG.
> >> >> >
> >> >> > Probably need to compile with gcc and with clang and look at the binary
> >> >> > differences. Or at least what objdump shows.
> >> >> >
> >> >>
> >> >> [ Hope to address this issue to the correct people - CCed some people
> >> >> I taped on their nerves ]
> >> >>
> >> >> Not sure if I should open a new thread?
> >> >> Please, some clear statements on this.
> >> >> Thanks.
> >> >>
> >> >> The issue is still visible and alive.
> >
> > I think it would be worthwhile to doublecheck the time at which
> > interrupts get disabled. Sedat, please try your plug/unplug the USB
> > mouse test with the patch below.
> >
> > Alan Stern
> >
> >
> >
> > Index: usb-4.4/drivers/hid/usbhid/hid-core.c
> > ===================================================================
> > --- usb-4.4.orig/drivers/hid/usbhid/hid-core.c
> > +++ usb-4.4/drivers/hid/usbhid/hid-core.c
> > @@ -1393,8 +1393,11 @@ static void usbhid_disconnect(struct usb
> >
> > static void hid_cancel_delayed_stuff(struct usbhid_device *usbhid)
> > {
> > + if (raw_irqs_disabled()) pr_info("usbhid irqs disabled A\n");
> > del_timer_sync(&usbhid->io_retry);
> > + if (raw_irqs_disabled()) pr_info("usbhid irqs disabled B\n");
> > cancel_work_sync(&usbhid->reset_work);
> > + if (raw_irqs_disabled()) pr_info("usbhid irqs disabled C\n");
> > }
> >
> > static void hid_cease_io(struct usbhid_device *usbhid)
> >
>
> With your patch I get the dmesg attached.

> [ 22.234758] usbhid irqs disabled A
> [ 22.234857] usbhid irqs disabled B
> [ 22.234912] BUG: sleeping function called from invalid context atkernel/workqueue.c:2688

That's a smoking gun. It means everyone has been looking in the wrong
place. Can you provide an objdump listing of usbhid_close()? The
routine starts like this:

void usbhid_close(struct hid_device *hid)
{
struct usbhid_device *usbhid = hid->driver_data;

mutex_lock(&hid_open_mut);

/* protecting hid->open to make sure we don't restart
* data acquistion due to a resumption we no longer
* care about
*/
spin_lock_irq(&usbhid->lock);
if (!--hid->open) {
spin_unlock_irq(&usbhid->lock);
hid_cancel_delayed_stuff(usbhid);

It appears that the spin_unlock_irq() call isn't working.

For extra thoroughness, try putting one of those raw_irqs_disabled()
checks just before and one just after the spin_lock_irq() line above.
Maybe also before the mutex_lock() line.

Alan Stern

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