net: mscc: ocelot: better error handling in ocelot_xtr_irq_handler

The ocelot_rx_frame_word() function can return a negative error code,
however this isn't being checked for consistently. Errors being ignored
have not been seen in practice though.

Also, some constructs can be simplified by using "goto" instead of
repeated "break" statements.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mscc/ocelot_vsc7514.c

@@ -619,12 +619,9 @@ static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 		for (i = 0; i < OCELOT_TAG_LEN / 4; i++) {
 			err = ocelot_rx_frame_word(ocelot, grp, true, &ifh[i]);
 			if (err != 4)
-				break;
+				goto out;
 		}
 
-		if (err != 4)
-			break;
-
 		/* At this point the IFH was read correctly, so it is safe to
 		 * presume that there is no error. The err needs to be reset
 		 * otherwise a frame could come in CPU queue between the while
@@ -645,7 +642,7 @@ static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 		if (unlikely(!skb)) {
 			netdev_err(dev, "Unable to allocate sk_buff\n");
 			err = -ENOMEM;
-			break;
+			goto out;
 		}
 		buf_len = info.len - ETH_FCS_LEN;
 		buf = (u32 *)skb_put(skb, buf_len);
@@ -653,12 +650,21 @@ static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 		len = 0;
 		do {
 			sz = ocelot_rx_frame_word(ocelot, grp, false, &val);
+			if (sz < 0) {
+				err = sz;
+				goto out;
+			}
 			*buf++ = val;
 			len += sz;
 		} while (len < buf_len);
 
 		/* Read the FCS */
 		sz = ocelot_rx_frame_word(ocelot, grp, false, &val);
+		if (sz < 0) {
+			err = sz;
+			goto out;
+		}
+
 		/* Update the statistics if part of the FCS was read before */
 		len -= ETH_FCS_LEN - sz;
 
@@ -667,11 +673,6 @@ static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 			*buf = val;
 		}
 
-		if (sz < 0) {
-			err = sz;
-			break;
-		}
-
 		if (ocelot->ptp) {
 			ocelot_ptp_gettime64(&ocelot->ptp_info, &ts);
 
@@ -701,6 +702,7 @@ static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 		dev->stats.rx_packets++;
 	}
 
+out:
 	if (err < 0)
 		while (ocelot_read(ocelot, QS_XTR_DATA_PRESENT) & BIT(grp))
 			ocelot_read_rix(ocelot, QS_XTR_RD, grp);