linux-kernel - [PATCH 3.16 32/83] net: tc35815: Explicitly check NET_IP_ALIGN is not zero in tc35815

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Date:   Wed, 20 Nov 2019 15:37:42 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Nathan Chancellor" <natechancellor@...il.com>
Subject: [PATCH 3.16 32/83] net: tc35815: Explicitly check NET_IP_ALIGN is
 not zero in tc35815_rx

3.16.78-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nathan Chancellor <natechancellor@...il.com>

commit 125b7e0949d4e72b15c2b1a1590f8cece985a918 upstream.

clang warns:

drivers/net/ethernet/toshiba/tc35815.c:1507:30: warning: use of logical
'&&' with constant operand [-Wconstant-logical-operand]
                        if (!HAVE_DMA_RXALIGN(lp) && NET_IP_ALIGN)
                                                  ^  ~~~~~~~~~~~~
drivers/net/ethernet/toshiba/tc35815.c:1507:30: note: use '&' for a
bitwise operation
                        if (!HAVE_DMA_RXALIGN(lp) && NET_IP_ALIGN)
                                                  ^~
                                                  &
drivers/net/ethernet/toshiba/tc35815.c:1507:30: note: remove constant to
silence this warning
                        if (!HAVE_DMA_RXALIGN(lp) && NET_IP_ALIGN)
                                                 ~^~~~~~~~~~~~~~~
1 warning generated.

Explicitly check that NET_IP_ALIGN is not zero, which matches how this
is checked in other parts of the tree. Because NET_IP_ALIGN is a build
time constant, this check will be constant folded away during
optimization.

Fixes: 82a9928db560 ("tc35815: Enable StripCRC feature")
Link: https://github.com/ClangBuiltLinux/linux/issues/608
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/net/ethernet/toshiba/tc35815.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/toshiba/tc35815.c
+++ b/drivers/net/ethernet/toshiba/tc35815.c
@@ -1528,7 +1528,7 @@ tc35815_rx(struct net_device *dev, int l
 			pci_unmap_single(lp->pci_dev,
 					 lp->rx_skbs[cur_bd].skb_dma,
 					 RX_BUF_SIZE, PCI_DMA_FROMDEVICE);
-			if (!HAVE_DMA_RXALIGN(lp) && NET_IP_ALIGN)
+			if (!HAVE_DMA_RXALIGN(lp) && NET_IP_ALIGN != 0)
 				memmove(skb->data, skb->data - NET_IP_ALIGN,
 					pkt_len);
 			data = skb_put(skb, pkt_len);