cdc-acm: handle read pipe errors

Read urbs are submitted back only on success, causing read pipe
running out of urbs after few errors. No more characters can
be read from tty device then until it is reopened and no errors
are reported.
Fix that by always submitting urbs back and clearing stall on
-EPIPE.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 50 insertions, 10 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index cf2029464ca4..d053075a8444 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -429,27 +429,41 @@ static void acm_read_bulk_callback(struct urb *urb)
 	dev_vdbg(&acm->data->dev, "got urb %d, len %d, status %d\n",
 		rb->index, urb->actual_length, status);
 
+	set_bit(rb->index, &acm->read_urbs_free);
+
 	if (!acm->dev) {
-		set_bit(rb->index, &acm->read_urbs_free);
 		dev_dbg(&acm->data->dev, "%s - disconnected\n", __func__);
 		return;
 	}
 
-	if (status) {
-		set_bit(rb->index, &acm->read_urbs_free);
-		if ((status != -ENOENT) || (urb->actual_length == 0))
-			return;
+	switch (status) {
+	case 0:
+		usb_mark_last_busy(acm->dev);
+		acm_process_read_urb(acm, urb);
+		break;
+	case -EPIPE:
+		set_bit(EVENT_RX_STALL, &acm->flags);
+		schedule_work(&acm->work);
+		return;
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		dev_dbg(&acm->data->dev,
+			"%s - urb shutting down with status: %d\n",
+			__func__, status);
+		return;
+	default:
+		dev_dbg(&acm->data->dev,
+			"%s - nonzero urb status received: %d\n",
+			__func__, status);
+		break;
 	}
 
-	usb_mark_last_busy(acm->dev);
-
-	acm_process_read_urb(acm, urb);
 	/*
 	 * Unthrottle may run on another CPU which needs to see events
 	 * in the same order. Submission has an implict barrier
 	 */
 	smp_mb__before_atomic();
-	set_bit(rb->index, &acm->read_urbs_free);
 
 	/* throttle device if requested by tty */
 	spin_lock_irqsave(&acm->read_lock, flags);
@@ -479,14 +493,30 @@ static void acm_write_bulk(struct urb *urb)
 	spin_lock_irqsave(&acm->write_lock, flags);
 	acm_write_done(acm, wb);
 	spin_unlock_irqrestore(&acm->write_lock, flags);
+	set_bit(EVENT_TTY_WAKEUP, &acm->flags);
 	schedule_work(&acm->work);
 }
 
 static void acm_softint(struct work_struct *work)
 {
+	int i;
 	struct acm *acm = container_of(work, struct acm, work);
 
-	tty_port_tty_wakeup(&acm->port);
+	if (test_bit(EVENT_RX_STALL, &acm->flags)) {
+		if (!(usb_autopm_get_interface(acm->data))) {
+			for (i = 0; i < acm->rx_buflimit; i++)
+				usb_kill_urb(acm->read_urbs[i]);
+			usb_clear_halt(acm->dev, acm->in);
+			acm_submit_read_urbs(acm, GFP_KERNEL);
+			usb_autopm_put_interface(acm->data);
+		}
+		clear_bit(EVENT_RX_STALL, &acm->flags);
+	}
+
+	if (test_bit(EVENT_TTY_WAKEUP, &acm->flags)) {
+		tty_port_tty_wakeup(&acm->port);
+		clear_bit(EVENT_TTY_WAKEUP, &acm->flags);
+	}
 }
 
 /*
@@ -1631,6 +1661,15 @@ static int acm_reset_resume(struct usb_interface *intf)
 
 #endif /* CONFIG_PM */
 
+static int acm_pre_reset(struct usb_interface *intf)
+{
+	struct acm *acm = usb_get_intfdata(intf);
+
+	clear_bit(EVENT_RX_STALL, &acm->flags);
+
+	return 0;
+}
+
 #define NOKIA_PCSUITE_ACM_INFO(x) \
 		USB_DEVICE_AND_INTERFACE_INFO(0x0421, x, \
 		USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM, \
@@ -1872,6 +1911,7 @@ static struct usb_driver acm_driver = {
 	.resume =	acm_resume,
 	.reset_resume =	acm_reset_resume,
 #endif
+	.pre_reset =	acm_pre_reset,
 	.id_table =	acm_ids,
 #ifdef CONFIG_PM
 	.supports_autosuspend = 1,