Commit 08e0ae03 authored by Ben Hutchings's avatar Ben Hutchings Committed by Luis Henriques

usbnet: Fix tx_bytes statistic running backward in cdc_ncm

commit 7a1e890e upstream.

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: beeecd42 ("net: cdc_ncm/cdc_mbim: adding NCM protocol statistics")
Signed-off-by: default avatarBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: default avatarBjørn Mork <bjorn@mork.no>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 7d2237ad
...@@ -189,7 +189,7 @@ struct sk_buff *asix_tx_fixup(struct usbnet *dev, struct sk_buff *skb, ...@@ -189,7 +189,7 @@ struct sk_buff *asix_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
skb_put(skb, sizeof(padbytes)); skb_put(skb, sizeof(padbytes));
} }
usbnet_set_skb_tx_stats(skb, 1); usbnet_set_skb_tx_stats(skb, 1, 0);
return skb; return skb;
} }
......
...@@ -1177,13 +1177,12 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev, struct sk_buff *skb, __le32 sign) ...@@ -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_overhead += skb_out->len - ctx->tx_curr_frame_payload;
ctx->tx_ntbs++; 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 * Adjust the stats so that the tx_bytes counter show real
* payload data instead. * payload data instead.
*/ */
dev->net->stats.tx_bytes -= skb_out->len - ctx->tx_curr_frame_payload; usbnet_set_skb_tx_stats(skb_out, n,
ctx->tx_curr_frame_payload - skb_out->len);
usbnet_set_skb_tx_stats(skb_out, n);
return skb_out; return skb_out;
......
...@@ -144,7 +144,7 @@ static struct sk_buff *sr_tx_fixup(struct usbnet *dev, struct sk_buff *skb, ...@@ -144,7 +144,7 @@ static struct sk_buff *sr_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
skb_put(skb, sizeof(padbytes)); skb_put(skb, sizeof(padbytes));
} }
usbnet_set_skb_tx_stats(skb, 1); usbnet_set_skb_tx_stats(skb, 1, 0);
return skb; return skb;
} }
......
...@@ -1322,9 +1322,19 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, ...@@ -1322,9 +1322,19 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
} else } else
urb->transfer_flags |= URB_ZERO_PACKET; urb->transfer_flags |= URB_ZERO_PACKET;
} }
entry->length = urb->transfer_buffer_length = length; urb->transfer_buffer_length = length;
if (!(info->flags & FLAG_MULTI_PACKET))
usbnet_set_skb_tx_stats(skb, 1); 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); spin_lock_irqsave(&dev->txq.lock, flags);
retval = usb_autopm_get_interface_async(dev->intf); retval = usb_autopm_get_interface_async(dev->intf);
......
...@@ -220,7 +220,7 @@ struct skb_data { /* skb->cb is one of these */ ...@@ -220,7 +220,7 @@ struct skb_data { /* skb->cb is one of these */
struct urb *urb; struct urb *urb;
struct usbnet *dev; struct usbnet *dev;
enum skb_state state; enum skb_state state;
size_t length; long length;
unsigned long packets; unsigned long packets;
}; };
...@@ -228,11 +228,13 @@ struct skb_data { /* skb->cb is one of these */ ...@@ -228,11 +228,13 @@ struct skb_data { /* skb->cb is one of these */
* tx_fixup method before returning an skb. * tx_fixup method before returning an skb.
*/ */
static inline void 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; struct skb_data *entry = (struct skb_data *) skb->cb;
entry->packets = packets; entry->packets = packets;
entry->length = bytes_delta;
} }
extern int usbnet_open(struct net_device *net); extern int usbnet_open(struct net_device *net);
......
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