From patchwork Tue Mar 12 09:51:42 2019
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X-Patchwork-Submitter: Stanislaw Gruszka <sgruszka@redhat.com>
X-Patchwork-Id: 10848961
X-Patchwork-Delegate: kvalo@adurom.com
From: Stanislaw Gruszka <sgruszka@redhat.com>
To: linux-wireless@vger.kernel.org
Cc: =?utf-8?q?Tomislav_Po=C5=BEega?= <pozega.tomislav@gmail.com>,
 Daniel Golle <daniel@makrotopia.org>, Felix Fietkau <nbd@nbd.name>,
 Mathias Kresin <dev@kresin.me>
Subject: [PATCH v3 3/4] rt2x00: check number of EPROTO errors
Date: Tue, 12 Mar 2019 10:51:42 +0100
Message-Id: <1552384303-29529-4-git-send-email-sgruszka@redhat.com>
In-Reply-To: <1552384303-29529-1-git-send-email-sgruszka@redhat.com>
References: <1552384303-29529-1-git-send-email-sgruszka@redhat.com>

Some USB host devices/drivers on some conditions can always return
EPROTO error on submitted URBs. That can cause infinity loop in the
rt2x00 driver.

Since we can have single EPROTO errors we can not mark as device as
removed to avoid infinity loop. However we can count consecutive
EPROTO errors and mark device as removed if get lot of it.
I choose number 10 as threshold.

Reported-and-tested-by: Randy Oostdyk <linux-kernel@oostdyk.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
 drivers/net/wireless/ralink/rt2x00/rt2x00.h    |  1 +
 drivers/net/wireless/ralink/rt2x00/rt2x00usb.c | 22 +++++++++++++++++++---
 2 files changed, 20 insertions(+), 3 deletions(-)

--- a/drivers/net/wireless/ralink/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00.h
@@ -1017,6 +1017,7 @@ struct rt2x00_dev {
 	unsigned int extra_tx_headroom;
 
 	struct usb_anchor *anchor;
+	unsigned int num_proto_errs;
 
 	/* Clock for System On Chip devices. */
 	struct clk *clk;
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
@@ -31,6 +31,22 @@
 #include "rt2x00.h"
 #include "rt2x00usb.h"
 
+static bool rt2x00usb_check_usb_error(struct rt2x00_dev *rt2x00dev, int status)
+{
+	if (status == -ENODEV || status == -ENOENT)
+		return true;
+
+	if (status == -EPROTO || status == -ETIMEDOUT)
+		rt2x00dev->num_proto_errs++;
+	else
+		rt2x00dev->num_proto_errs = 0;
+
+	if (rt2x00dev->num_proto_errs > 3)
+		return true;
+
+	return false;
+}
+
 /*
  * Interfacing with the HW.
  */
@@ -57,7 +73,7 @@ int rt2x00usb_vendor_request(struct rt2x
 		if (status >= 0)
 			return 0;
 
-		if (status == -ENODEV || status == -ENOENT) {
+		if (rt2x00usb_check_usb_error(rt2x00dev, status)) {
 			/* Device has disappeared. */
 			clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 			break;
@@ -321,7 +337,7 @@ static bool rt2x00usb_kick_tx_entry(stru
 
 	status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
 	if (status) {
-		if (status == -ENODEV || status == -ENOENT)
+		if (rt2x00usb_check_usb_error(rt2x00dev, status))
 			clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 		set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
 		rt2x00lib_dmadone(entry);
@@ -410,7 +426,7 @@ static bool rt2x00usb_kick_rx_entry(stru
 
 	status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
 	if (status) {
-		if (status == -ENODEV || status == -ENOENT)
+		if (rt2x00usb_check_usb_error(rt2x00dev, status))
 			clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 		set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
 		rt2x00lib_dmadone(entry);
