Commit 2df69484 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
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USB: cdc-wdm: don't enable interrupts in USB-giveback 



In the code path
  __usb_hcd_giveback_urb()
  -> wdm_in_callback()
   -> service_outstanding_interrupt()

The function service_outstanding_interrupt() will unconditionally enable
interrupts during unlock and invoke usb_submit_urb() with GFP_KERNEL.
If the HCD completes in BH (like ehci does) then the context remains
atomic due local_bh_disable() and enabling interrupts does not change
this.

Defer the error case handling to a workqueue as suggested by Oliver
Neukum. In case of an error the worker performs the read out and wakes
the user.

Fixes: c1da59da ("cdc-wdm: Clear read pipeline in case of error")
Cc: Robert Foss <robert.foss@collabora.com>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: default avatarOliver Neukum <oneukum@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4327059a

drivers/usb/class/cdc-wdm.c

+24 −7
Original line number Diff line number Diff line
@@ -96,6 +96,7 @@ struct wdm_device { 
	struct mutex		rlock;

	wait_queue_head_t	wait;

	struct work_struct	rxwork;

	struct work_struct	service_outs_intr;

	int			werr;

	int			rerr;

	int                     resp_count;
@@ -151,9 +152,6 @@ static void wdm_out_callback(struct urb *urb) 
	wake_up(&desc->wait);

}



/* forward declaration */

static int service_outstanding_interrupt(struct wdm_device *desc);



static void wdm_in_callback(struct urb *urb)

{

	struct wdm_device *desc = urb->context;
@@ -209,8 +207,6 @@ static void wdm_in_callback(struct urb *urb) 
		}

	}

skip_error:

	set_bit(WDM_READ, &desc->flags);

	wake_up(&desc->wait);



	if (desc->rerr) {

		/*
@@ -219,9 +215,11 @@ skip_error: 
		 * We should respond to further attempts from the device to send

		 * data, so that we can get unstuck.

		 */

		service_outstanding_interrupt(desc);

		schedule_work(&desc->service_outs_intr);

	} else {

		set_bit(WDM_READ, &desc->flags);

		wake_up(&desc->wait);

	}



	spin_unlock(&desc->iuspin);

}
@@ -758,6 +756,21 @@ static void wdm_rxwork(struct work_struct *work) 
	}

}



static void service_interrupt_work(struct work_struct *work)

{

	struct wdm_device *desc;



	desc = container_of(work, struct wdm_device, service_outs_intr);



	spin_lock_irq(&desc->iuspin);

	service_outstanding_interrupt(desc);

	if (!desc->resp_count) {

		set_bit(WDM_READ, &desc->flags);

		wake_up(&desc->wait);

	}

	spin_unlock_irq(&desc->iuspin);

}



/* --- hotplug --- */



static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
@@ -779,6 +792,7 @@ static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor 
	desc->inum = cpu_to_le16((u16)intf->cur_altsetting->desc.bInterfaceNumber);

	desc->intf = intf;

	INIT_WORK(&desc->rxwork, wdm_rxwork);

	INIT_WORK(&desc->service_outs_intr, service_interrupt_work);



	rv = -EINVAL;

	if (!usb_endpoint_is_int_in(ep))
@@ -964,6 +978,7 @@ static void wdm_disconnect(struct usb_interface *intf) 
	mutex_lock(&desc->wlock);

	kill_urbs(desc);

	cancel_work_sync(&desc->rxwork);

	cancel_work_sync(&desc->service_outs_intr);

	mutex_unlock(&desc->wlock);

	mutex_unlock(&desc->rlock);
@@ -1006,6 +1021,7 @@ static int wdm_suspend(struct usb_interface *intf, pm_message_t message) 
		/* callback submits work - order is essential */

		kill_urbs(desc);

		cancel_work_sync(&desc->rxwork);

		cancel_work_sync(&desc->service_outs_intr);

	}

	if (!PMSG_IS_AUTO(message)) {

		mutex_unlock(&desc->wlock);
@@ -1065,6 +1081,7 @@ static int wdm_pre_reset(struct usb_interface *intf) 
	mutex_lock(&desc->wlock);

	kill_urbs(desc);

	cancel_work_sync(&desc->rxwork);

	cancel_work_sync(&desc->service_outs_intr);

	return 0;

}

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