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 <[email protected]> Acked-by: Oliver Neukum <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
torvalds · Nov 21, 2016 · 1aba579 · 1aba579
1 parent d305394
commit 1aba579
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Showing 2 changed files with 53 additions and 10 deletions.
diff --git 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,

diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
@@ -103,6 +103,9 @@ struct acm {
 	spinlock_t write_lock;
 	struct mutex mutex;
 	bool disconnected;
+	unsigned long flags;
+#		define EVENT_TTY_WAKEUP	0
+#		define EVENT_RX_STALL	1
 	struct usb_cdc_line_coding line;		/* bits, stop, parity */
 	struct work_struct work;			/* work queue entry for line discipline waking up */
 	unsigned int ctrlin;				/* input control lines (DCD, DSR, RI, break, overruns) */