USB CDC NCM: tx_fixup() race condition fix

- tx_fixup() can be called from either timer callback or from xmit()
  in usbnet, so spinlock is added to avoid concurrency-related problem.
- minor correction due to checkpatch warning for some line over 80
  chars after previous patch was applied.

Signed-off-by: Alexey Orishko <alexey.orishko@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 7 deletions

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index d776c4a8d3c1..04e8ce14a1d0 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -54,7 +54,7 @@
 #include <linux/usb/usbnet.h>
 #include <linux/usb/cdc.h>
 
-#define DRIVER_VERSION                          "30-Nov-2010"
+#define DRIVER_VERSION                          "17-Jan-2011"
 
 /* CDC NCM subclass 3.2.1 */
 #define USB_CDC_NCM_NDP16_LENGTH_MIN            0x10
@@ -868,15 +868,19 @@ static void cdc_ncm_tx_timeout(unsigned long arg)
         if (ctx->tx_timer_pending != 0) {
                 ctx->tx_timer_pending--;
                 restart = 1;
-        } else
+        } else {
                 restart = 0;
+        }
 
         spin_unlock(&ctx->mtx);
 
-        if (restart)
+        if (restart) {
+                spin_lock(&ctx->mtx);
                 cdc_ncm_tx_timeout_start(ctx);
-        else if (ctx->netdev != NULL)
+                spin_unlock(&ctx->mtx);
+        } else if (ctx->netdev != NULL) {
                 usbnet_start_xmit(NULL, ctx->netdev);
+        }
 }
 
 static struct sk_buff *
@@ -900,7 +904,6 @@ cdc_ncm_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
         skb_out = cdc_ncm_fill_tx_frame(ctx, skb);
         if (ctx->tx_curr_skb != NULL)
                 need_timer = 1;
-        spin_unlock(&ctx->mtx);
 
         /* Start timer, if there is a remaining skb */
         if (need_timer)
@@ -908,6 +911,8 @@ cdc_ncm_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
 
         if (skb_out)
                 dev->net->stats.tx_packets += ctx->tx_curr_frame_num;
+
+        spin_unlock(&ctx->mtx);
         return skb_out;
 
 error:
@@ -1020,8 +1025,8 @@ static int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in)
                 if (((offset + temp) > actlen) ||
                     (temp > CDC_NCM_MAX_DATAGRAM_SIZE) || (temp < ETH_HLEN)) {
                         pr_debug("invalid frame detected (ignored)"
-                                "offset[%u]=%u, length=%u, skb=%p\n",
-                                                        x, offset, temp, skb_in);
+                                        "offset[%u]=%u, length=%u, skb=%p\n",
+                                        x, offset, temp, skb_in);
                         if (!x)
                                 goto error;
                         break;