usb: cdc-acm: use irqsave() in USB's complete callback

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: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index ed0475c6602d5447b4c563679441ac27a4675079..24686f8eb6d3b1127255f395787f819e6584cf4e 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -276,6 +276,7 @@ static void acm_process_notification(struct acm *acm, unsigned char *buf)
 {
        int newctrl;
        int difference;
+       unsigned long flags;
        struct usb_cdc_notification *dr = (struct usb_cdc_notification *)buf;
        unsigned char *data = buf + sizeof(struct usb_cdc_notification);
 
@@ -303,7 +304,7 @@ static void acm_process_notification(struct acm *acm, unsigned char *buf)
                }
 
                difference = acm->ctrlin ^ newctrl;
-               spin_lock(&acm->read_lock);
+               spin_lock_irqsave(&acm->read_lock, flags);
                acm->ctrlin = newctrl;
                acm->oldcount = acm->iocount;
 
@@ -321,7 +322,7 @@ static void acm_process_notification(struct acm *acm, unsigned char *buf)
                        acm->iocount.parity++;
                if (difference & ACM_CTRL_OVERRUN)
                        acm->iocount.overrun++;
-               spin_unlock(&acm->read_lock);
+               spin_unlock_irqrestore(&acm->read_lock, flags);
 
                if (difference)
                        wake_up_all(&acm->wioctl);