net: cdc_ncm: add "ndp_to_end" sysfs attribute

Adding a writable sysfs attribute for the "NDP to end"
quirk flag.

This makes it easier for end users to test new devices for
this firmware bug.  We've been lucky so far, but we should
not depend on reporters capable of rebuilding the driver.

Cc: Enrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 3b1ba8237768..b45e5cae2a6b 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -283,6 +283,48 @@ static DEVICE_ATTR(rx_max, S_IRUGO | S_IWUSR, cdc_ncm_show_rx_max, cdc_ncm_store
 static DEVICE_ATTR(tx_max, S_IRUGO | S_IWUSR, cdc_ncm_show_tx_max, cdc_ncm_store_tx_max);
 static DEVICE_ATTR(tx_timer_usecs, S_IRUGO | S_IWUSR, cdc_ncm_show_tx_timer_usecs, cdc_ncm_store_tx_timer_usecs);
 
+static ssize_t ndp_to_end_show(struct device *d, struct device_attribute *attr, char *buf)
+{
+	struct usbnet *dev = netdev_priv(to_net_dev(d));
+	struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
+
+	return sprintf(buf, "%c\n", ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END ? 'Y' : 'N');
+}
+
+static ssize_t ndp_to_end_store(struct device *d,  struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct usbnet *dev = netdev_priv(to_net_dev(d));
+	struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
+	bool enable;
+
+	if (strtobool(buf, &enable))
+		return -EINVAL;
+
+	/* no change? */
+	if (enable == (ctx->drvflags & CDC_NCM_FLAG_NDP_TO_END))
+		return len;
+
+	if (enable && !ctx->delayed_ndp16) {
+		ctx->delayed_ndp16 = kzalloc(ctx->max_ndp_size, GFP_KERNEL);
+		if (!ctx->delayed_ndp16)
+			return -ENOMEM;
+	}
+
+	/* flush pending data before changing flag */
+	netif_tx_lock_bh(dev->net);
+	usbnet_start_xmit(NULL, dev->net);
+	spin_lock_bh(&ctx->mtx);
+	if (enable)
+		ctx->drvflags |= CDC_NCM_FLAG_NDP_TO_END;
+	else
+		ctx->drvflags &= ~CDC_NCM_FLAG_NDP_TO_END;
+	spin_unlock_bh(&ctx->mtx);
+	netif_tx_unlock_bh(dev->net);
+
+	return len;
+}
+static DEVICE_ATTR_RW(ndp_to_end);
+
 #define NCM_PARM_ATTR(name, format, tocpu)				\
 static ssize_t cdc_ncm_show_##name(struct device *d, struct device_attribute *attr, char *buf) \
 { \
@@ -305,6 +347,7 @@ NCM_PARM_ATTR(wNtbOutMaxDatagrams, "%u", le16_to_cpu);
 
 static struct attribute *cdc_ncm_sysfs_attrs[] = {
 	&dev_attr_min_tx_pkt.attr,
+	&dev_attr_ndp_to_end.attr,
 	&dev_attr_rx_max.attr,
 	&dev_attr_tx_max.attr,
 	&dev_attr_tx_timer_usecs.attr,