From:   Stanislaw Gruszka <sgruszka@redhat.com>
To:     Felix Fietkau <nbd@nbd.name>
Cc:     linux-wireless@vger.kernel.org,
        Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Subject: [RFC] mt76x02u: correct pad for fragments
Date:   Mon, 11 Feb 2019 09:37:44 +0100
Message-Id: <1549874264-7661-1-git-send-email-sgruszka@redhat.com>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

Modifying skb->len & data_len doesn't look correct. Issue is not critical
we just pad 2 times, except first padding is not filled with zeros.

However I'm not sure if we should not add pad to all skb's in frags
list.

Additionally remove unlikely(pad) condition, we always pad for at least
four bytes what is needed by HW.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
 .../wireless/mediatek/mt76/mt76x02_usb_core.c | 22 +++++++------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c b/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c
index dc2226c722dd..c7ca2d93720a 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c
@@ -49,21 +49,15 @@ int mt76x02u_skb_dma_info(struct sk_buff *skb, int port, u32 flags)
 	       FIELD_PREP(MT_TXD_INFO_DPORT, port) | flags;
 	put_unaligned_le32(info, skb_push(skb, sizeof(info)));
 
-	pad = round_up(skb->len, 4) + 4 - skb->len;
-	skb_walk_frags(skb, iter) {
+	skb_walk_frags(skb, iter)
 		last = iter;
-		if (!iter->next) {
-			skb->data_len += pad;
-			skb->len += pad;
-			break;
-		}
-	}
-
-	if (unlikely(pad)) {
-		if (skb_pad(last, pad))
-			return -ENOMEM;
-		__skb_put(last, pad);
-	}
+
+	/* Add zero pad of 4 - 7 bytes at the end of buffer */
+	pad = round_up(skb->len, 4) + 4 - skb->len;
+	if (skb_pad(last, pad))
+		return -ENOMEM;
+	__skb_put(last, pad);
+
 	return 0;
 }
 
-- 
2.19.2