bnx2x: Rx work check

The has Rx work check was wrong: when the FW was at the end of the page,
the driver was already at the beginning of the next page. Since the
check only validated that both driver and FW are pointing to the same
place, it concluded that there is still work to be done. This caused
some serious issues including long latency results on ping-pong test and
lockups while unloading the driver in that condition.

Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bnx2x.h

@@ -271,7 +271,7 @@ struct bnx2x_fastpath {
 			 (fp->tx_pkt_prod != fp->tx_pkt_cons))
 
 #define BNX2X_HAS_RX_WORK(fp) \
-			(fp->rx_comp_cons != le16_to_cpu(*fp->rx_cons_sb))
+			(fp->rx_comp_cons != rx_cons_sb)
 
 #define BNX2X_HAS_WORK(fp)	(BNX2X_HAS_RX_WORK(fp) || BNX2X_HAS_TX_WORK(fp))
 

drivers/net/bnx2x_main.c

@@ -9250,6 +9250,7 @@ static int bnx2x_poll(struct napi_struct *napi, int budget)
 						 napi);
 	struct bnx2x *bp = fp->bp;
 	int work_done = 0;
+	u16 rx_cons_sb;
 
 #ifdef BNX2X_STOP_ON_ERROR
 	if (unlikely(bp->panic))
@@ -9265,10 +9266,16 @@ static int bnx2x_poll(struct napi_struct *napi, int budget)
 	if (BNX2X_HAS_TX_WORK(fp))
 		bnx2x_tx_int(fp, budget);
 
+	rx_cons_sb = le16_to_cpu(*fp->rx_cons_sb);
+	if ((rx_cons_sb & MAX_RCQ_DESC_CNT) == MAX_RCQ_DESC_CNT)
+		rx_cons_sb++;
 	if (BNX2X_HAS_RX_WORK(fp))
 		work_done = bnx2x_rx_int(fp, budget);
 
 	rmb(); /* BNX2X_HAS_WORK() reads the status block */
+	rx_cons_sb = le16_to_cpu(*fp->rx_cons_sb);
+	if ((rx_cons_sb & MAX_RCQ_DESC_CNT) == MAX_RCQ_DESC_CNT)
+		rx_cons_sb++;
 
 	/* must not complete if we consumed full budget */
 	if ((work_done < budget) && !BNX2X_HAS_WORK(fp)) {