From: Oliver Neukum <oneukum@suse.de>
Date: Wed, 28 Mar 2012 11:16:19 +0000 (+0200)
Subject: HID: usbhid: fix error handling of not enough bandwidth
X-Git-Url: https://rtime.felk.cvut.cz/gitweb/linux-imx.git/commitdiff_plain/a8c52b662cef520815ed43cb3305f8b45b452694

HID: usbhid: fix error handling of not enough bandwidth

In case IO cannot be started because there is a lack of bandwidth
on the bus, it makes no sense to reset the device. If IO is requested
because the device is opened, user space should be notified with
an error right away. If the lack of bandwidth arises later, for
example after resume, there's no other choice but to retry in the
hope that bandwidth will be freed.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 5bf91dbad59d..c1a1dd54601c 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -86,8 +86,13 @@ static int hid_start_in(struct hid_device *hid)
 			!test_bit(HID_REPORTED_IDLE, &usbhid->iofl) &&
 			!test_and_set_bit(HID_IN_RUNNING, &usbhid->iofl)) {
 		rc = usb_submit_urb(usbhid->urbin, GFP_ATOMIC);
-		if (rc != 0)
+		if (rc != 0) {
 			clear_bit(HID_IN_RUNNING, &usbhid->iofl);
+			if (rc == -ENOSPC)
+				set_bit(HID_NO_BANDWIDTH, &usbhid->iofl);
+		} else {
+			clear_bit(HID_NO_BANDWIDTH, &usbhid->iofl);
+		}
 	}
 	spin_unlock_irqrestore(&usbhid->lock, flags);
 	return rc;
@@ -173,8 +178,10 @@ static void hid_io_error(struct hid_device *hid)
 
 	if (time_after(jiffies, usbhid->stop_retry)) {
 
-		/* Retries failed, so do a port reset */
-		if (!test_and_set_bit(HID_RESET_PENDING, &usbhid->iofl)) {
+		/* Retries failed, so do a port reset unless we lack bandwidth*/
+		if (test_bit(HID_NO_BANDWIDTH, &usbhid->iofl)
+		     && !test_and_set_bit(HID_RESET_PENDING, &usbhid->iofl)) {
+
 			schedule_work(&usbhid->reset_work);
 			goto done;
 		}
@@ -700,7 +707,7 @@ static int hid_get_class_descriptor(struct usb_device *dev, int ifnum,
 int usbhid_open(struct hid_device *hid)
 {
 	struct usbhid_device *usbhid = hid->driver_data;
-	int res;
+	int res = 0;
 
 	mutex_lock(&hid_open_mut);
 	if (!hid->open++) {
@@ -708,17 +715,27 @@ int usbhid_open(struct hid_device *hid)
 		/* the device must be awake to reliably request remote wakeup */
 		if (res < 0) {
 			hid->open--;
-			mutex_unlock(&hid_open_mut);
-			return -EIO;
+			res = -EIO;
+			goto done;
 		}
 		usbhid->intf->needs_remote_wakeup = 1;
-		if (hid_start_in(hid))
-			hid_io_error(hid);
- 
+		res = hid_start_in(hid);
+		if (res) {
+			if (res != -ENOSPC) {
+				hid_io_error(hid);
+				res = 0;
+			} else {
+				/* no use opening if resources are insufficient */
+				hid->open--;
+				res = -EBUSY;
+				usbhid->intf->needs_remote_wakeup = 0;
+			}
+		}
 		usb_autopm_put_interface(usbhid->intf);
 	}
+done:
 	mutex_unlock(&hid_open_mut);
-	return 0;
+	return res;
 }
 
 void usbhid_close(struct hid_device *hid)
diff --git a/drivers/hid/usbhid/usbhid.h b/drivers/hid/usbhid/usbhid.h
index cb8f703efde5..1883d7b94870 100644
--- a/drivers/hid/usbhid/usbhid.h
+++ b/drivers/hid/usbhid/usbhid.h
@@ -55,6 +55,7 @@ struct usb_interface *usbhid_find_interface(int minor);
 #define HID_STARTED		8
 #define HID_REPORTED_IDLE	9
 #define HID_KEYS_PRESSED	10
+#define HID_NO_BANDWIDTH	11
 
 /*
  * USB-specific HID struct, to be pointed to