From 7a1e890e2168e33fb62d84528e996b8b4b478fea Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Wed, 25 Mar 2015 21:41:33 +0100 Subject: [PATCH] usbnet: Fix tx_bytes statistic running backward in cdc_ncm MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit cdc_ncm disagrees with usbnet about how much framing overhead should be counted in the tx_bytes statistics, and tries 'fix' this by decrementing tx_bytes on the transmit path. But statistics must never be decremented except due to roll-over; this will thoroughly confuse user-space. Also, tx_bytes is only incremented by usbnet in the completion path. Fix this by requiring drivers that set FLAG_MULTI_FRAME to set a tx_bytes delta along with the tx_packets count. Fixes: beeecd42c3b4 ("net: cdc_ncm/cdc_mbim: adding NCM protocol statistics") Signed-off-by: Ben Hutchings Signed-off-by: Bjørn Mork --- drivers/net/usb/asix_common.c | 2 +- drivers/net/usb/cdc_ncm.c | 7 +++---- drivers/net/usb/sr9800.c | 2 +- drivers/net/usb/usbnet.c | 16 +++++++++++++--- include/linux/usb/usbnet.h | 6 ++++-- 5 files changed, 22 insertions(+), 11 deletions(-) diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c index 724a9b50df7a..75d6f26729a3 100644 --- a/drivers/net/usb/asix_common.c +++ b/drivers/net/usb/asix_common.c @@ -189,7 +189,7 @@ struct sk_buff *asix_tx_fixup(struct usbnet *dev, struct sk_buff *skb, skb_put(skb, sizeof(padbytes)); } - usbnet_set_skb_tx_stats(skb, 1); + usbnet_set_skb_tx_stats(skb, 1, 0); return skb; } diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index 70cbea551139..c3e4da9e79ca 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -1177,13 +1177,12 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign) ctx->tx_overhead += skb_out->len - ctx->tx_curr_frame_payload; ctx->tx_ntbs++; - /* usbnet has already counted all the framing overhead. + /* usbnet will count all the framing overhead by default. * Adjust the stats so that the tx_bytes counter show real * payload data instead. */ - dev->net->stats.tx_bytes -= skb_out->len - ctx->tx_curr_frame_payload; - - usbnet_set_skb_tx_stats(skb_out, n); + usbnet_set_skb_tx_stats(skb_out, n, + ctx->tx_curr_frame_payload - skb_out->len); return skb_out; diff --git a/drivers/net/usb/sr9800.c b/drivers/net/usb/sr9800.c index 7650cdc8fe6b..953de13267df 100644 --- a/drivers/net/usb/sr9800.c +++ b/drivers/net/usb/sr9800.c @@ -144,7 +144,7 @@ static struct sk_buff *sr_tx_fixup(struct usbnet *dev, struct sk_buff *skb, skb_put(skb, sizeof(padbytes)); } - usbnet_set_skb_tx_stats(skb, 1); + usbnet_set_skb_tx_stats(skb, 1, 0); return skb; } diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 0f3ff285f6a1..777757ae1973 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -1346,9 +1346,19 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, } else urb->transfer_flags |= URB_ZERO_PACKET; } - entry->length = urb->transfer_buffer_length = length; - if (!(info->flags & FLAG_MULTI_PACKET)) - usbnet_set_skb_tx_stats(skb, 1); + urb->transfer_buffer_length = length; + + if (info->flags & FLAG_MULTI_PACKET) { + /* Driver has set number of packets and a length delta. + * Calculate the complete length and ensure that it's + * positive. + */ + entry->length += length; + if (WARN_ON_ONCE(entry->length <= 0)) + entry->length = length; + } else { + usbnet_set_skb_tx_stats(skb, 1, length); + } spin_lock_irqsave(&dev->txq.lock, flags); retval = usb_autopm_get_interface_async(dev->intf); diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h index ff3fb2bd0e90..6e0ce8c7b8cb 100644 --- a/include/linux/usb/usbnet.h +++ b/include/linux/usb/usbnet.h @@ -227,7 +227,7 @@ struct skb_data { /* skb->cb is one of these */ struct urb *urb; struct usbnet *dev; enum skb_state state; - size_t length; + long length; unsigned long packets; }; @@ -235,11 +235,13 @@ struct skb_data { /* skb->cb is one of these */ * tx_fixup method before returning an skb. */ static inline void -usbnet_set_skb_tx_stats(struct sk_buff *skb, unsigned long packets) +usbnet_set_skb_tx_stats(struct sk_buff *skb, + unsigned long packets, long bytes_delta) { struct skb_data *entry = (struct skb_data *) skb->cb; entry->packets = packets; + entry->length = bytes_delta; } extern int usbnet_open(struct net_device *net); -- 2.34.1