r8152: check tx agg list before spin lock

Check tx agg list before spin lock to avoid doing spin lock every
times.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 8ecb41b..00b3192 100644 (file)
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -1266,6 +1266,9 @@ static struct tx_agg *r8152_get_tx_agg(struct r8152 *tp)
        struct tx_agg *agg = NULL;
        unsigned long flags;
 
+       if (list_empty(&tp->tx_free))
+               return NULL;
+
        spin_lock_irqsave(&tp->tx_lock, flags);
        if (!list_empty(&tp->tx_free)) {
                struct list_head *cursor;