netdev - [PATCH v3 net] staging: octeon: Drop on uncorrectable alignment or FCS error

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Date:   Fri, 16 Oct 2020 16:56:30 +0200
From:   Alexander A Sverdlin <alexander.sverdlin@...ia.com>
To:     devel@...verdev.osuosl.org
Cc:     Alexander Sverdlin <alexander.sverdlin@...ia.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Ralf Baechle <ralf@...ux-mips.org>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: [PATCH v3 net] staging: octeon: Drop on uncorrectable alignment or FCS error

From: Alexander Sverdlin <alexander.sverdlin@...ia.com>

Currently in case of alignment or FCS error if the packet cannot be
corrected it's still not dropped. Report the error properly and drop the
packet while making the code around a little bit more readable.

Fixes: 80ff0fd3ab ("Staging: Add octeon-ethernet driver files.")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...ia.com>
---
 drivers/staging/octeon/ethernet-rx.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

Changes in v3:
- Removed Change-Id tag
Changes in v2:
- whitespace alignment fix as suggested by Dan Carpenter
- fixed the logic to accept "corrected" packets (preambles 0xd, 0xd5)

diff --git a/drivers/staging/octeon/ethernet-rx.c b/drivers/staging/octeon/ethernet-rx.c
index 2c16230..9ebd665 100644
--- a/drivers/staging/octeon/ethernet-rx.c
+++ b/drivers/staging/octeon/ethernet-rx.c
@@ -69,15 +69,17 @@ static inline int cvm_oct_check_rcv_error(struct cvmx_wqe *work)
 	else
 		port = work->word1.cn38xx.ipprt;
 
-	if ((work->word2.snoip.err_code == 10) && (work->word1.len <= 64)) {
+	if ((work->word2.snoip.err_code == 10) && (work->word1.len <= 64))
 		/*
 		 * Ignore length errors on min size packets. Some
 		 * equipment incorrectly pads packets to 64+4FCS
 		 * instead of 60+4FCS.  Note these packets still get
 		 * counted as frame errors.
 		 */
-	} else if (work->word2.snoip.err_code == 5 ||
-		   work->word2.snoip.err_code == 7) {
+		return 0;
+
+	if (work->word2.snoip.err_code == 5 ||
+	    work->word2.snoip.err_code == 7) {
 		/*
 		 * We received a packet with either an alignment error
 		 * or a FCS error. This may be signalling that we are
@@ -108,7 +110,10 @@ static inline int cvm_oct_check_rcv_error(struct cvmx_wqe *work)
 				/* Port received 0xd5 preamble */
 				work->packet_ptr.s.addr += i + 1;
 				work->word1.len -= i + 5;
-			} else if ((*ptr & 0xf) == 0xd) {
+				return 0;
+			}
+
+			if ((*ptr & 0xf) == 0xd) {
 				/* Port received 0xd preamble */
 				work->packet_ptr.s.addr += i;
 				work->word1.len -= i + 4;
@@ -118,21 +123,20 @@ static inline int cvm_oct_check_rcv_error(struct cvmx_wqe *work)
 					    ((*(ptr + 1) & 0xf) << 4);
 					ptr++;
 				}
-			} else {
-				printk_ratelimited("Port %d unknown preamble, packet dropped\n",
-						   port);
-				cvm_oct_free_work(work);
-				return 1;
+				return 0;
 			}
+
+			printk_ratelimited("Port %d unknown preamble, packet dropped\n",
+					   port);
+			cvm_oct_free_work(work);
+			return 1;
 		}
-	} else {
-		printk_ratelimited("Port %d receive error code %d, packet dropped\n",
-				   port, work->word2.snoip.err_code);
-		cvm_oct_free_work(work);
-		return 1;
 	}
 
-	return 0;
+	printk_ratelimited("Port %d receive error code %d, packet dropped\n",
+			   port, work->word2.snoip.err_code);
+	cvm_oct_free_work(work);
+	return 1;
 }
 
 static void copy_segments_to_skb(struct cvmx_wqe *work, struct sk_buff *skb)
-- 
2.10.2