On Mon, 25 Jun 2018, Sebastian Andrzej Siewior wrote:
> The USB completion callback does not disable interrupts while acquiring
> the lock. We want to remove the local_irq_disable() invocation from
> __usb_hcd_giveback_urb() and therefore it is required for the callback
> handler to disable the interrupts while acquiring the lock.
> The callback may be invoked either in IRQ or BH context depending on the
> USB host controller.
> Use the _irqsave() variant of the locking primitives.
>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> ---
> drivers/usb/core/devio.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> index 476dcc5f2da3..cea35fa4e7a3 100644
> --- a/drivers/usb/core/devio.c
> +++ b/drivers/usb/core/devio.c
> @@ -585,9 +585,10 @@ static void async_completed(struct urb *urb)
> struct siginfo sinfo;
> struct pid *pid = NULL;
> const struct cred *cred = NULL;
> + unsigned long flags;
> int signr;
>
> - spin_lock(&ps->lock);
> + spin_lock_irqsave(&ps->lock, flags);
> list_move_tail(&as->asynclist, &ps->async_completed);
> as->status = urb->status;
> signr = as->signr;
> @@ -611,7 +612,7 @@ static void async_completed(struct urb *urb)
> cancel_bulk_urbs(ps, as->bulk_addr);
>
> wake_up(&ps->wait);
> - spin_unlock(&ps->lock);
> + spin_unlock_irqrestore(&ps->lock, flags);
>
> if (signr) {
> kill_pid_info_as_cred(sinfo.si_signo, &sinfo, pid, cred);
> @@ -1702,6 +1703,7 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
>
> as->urb->context = as;
> as->urb->complete = async_completed;
> +
This change is unrelated to the purpose of the patch. It should be
removed.
> for (totlen = u = 0; u < number_of_packets; u++) {
> as->urb->iso_frame_desc[u].offset = totlen;
> as->urb->iso_frame_desc[u].length = isopkt[u].length;
Aside from that:
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Alan Stern
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