linux-kernel - [PATCH v2] 3c59x: fix bad split of cpu_to_le32(pci_map

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Message-ID: <20140925151519.GA12225@erable>
Date:	Thu, 25 Sep 2014 15:15:19 +0000
From:	Sylvain 'ythier' Hitier <sylvain.hitier@...il.com>
To:	Neil Horman <nhorman@...driver.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Meelis Roos <mroos@...ux.ee>
Subject: [PATCH v2] 3c59x: fix bad split of cpu_to_le32(pci_map_single())

Hello,

When: 2014-09-24_3@...16-47 -0400
Who:  Neil Horman
What:
> You do probably want to fixup
> the changelog to be a bit more clear as to whats going on here.

Date:   Wed Sep 24 09:22:16 2014 +0000

3c59x: fix bad split of cpu_to_le32(pci_map_single())

In commit 6f2b6a3005b2c34c39f207a87667564f64f2f91a,
  # 3c59x: Add dma error checking and recovery
the intent is to split out the mapping from the byte-swapping in order to
insert a dma_mapping_error() check.

Kinda this semantic patch:

    // See http://coccinelle.lip6.fr/
    //
    // Beware, grouik-and-dirty!
    @@
    expression DEV, X, Y, Z;
    @@
    -   cpu_to_le32(pci_map_single(DEV, X, Y, Z))
    +   dma_addr_t addr = pci_map_single(DEV, X, Y, Z);
    +   if (dma_mapping_error(&DEV->dev, addr))
    +       /* snip */;
    +   cpu_to_le32(addr)

However, the #else part (of the #if DO_ZEROCOPY test) is changed this way:

    -   cpu_to_le32(pci_map_single(DEV, X, Y, Z))
    +   dma_addr_t addr = cpu_to_le32(pci_map_single(DEV, X, Y, Z));
    //                    ^^^^^^^^^^^
    //                    That mismatches the 3 other changes!
    +   if (dma_mapping_error(&DEV->dev, addr))
    +       /* snip */;
    +   cpu_to_le32(addr)

Let's remove the leftover cpu_to_le32() for coherency.

v2: Better changelog.

Fixes: 6f2b6a3005b2c34c39f207a87667564f64f2f91a
  # 3c59x: Add dma error checking and recovery
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Meelis Roos <mroos@...ux.ee>
Cc: Neil Horman <nhorman@...driver.com>
Signed-off-by: Sylvain "ythier" Hitier <sylvain.hitier@...il.com>
---
 drivers/net/ethernet/3com/3c59x.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/3com/3c59x.c b/drivers/net/ethernet/3com/3c59x.c
index 8ca49f04..0a3108b3 100644
--- a/drivers/net/ethernet/3com/3c59x.c
+++ b/drivers/net/ethernet/3com/3c59x.c
@@ -2214,7 +2214,7 @@ boomerang_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		}
 	}
 #else
-	dma_addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->data, skb->len, PCI_DMA_TODEVICE));
+	dma_addr = pci_map_single(VORTEX_PCI(vp), skb->data, skb->len, PCI_DMA_TODEVICE);
 	if (dma_mapping_error(&VORTEX_PCI(vp)->dev, dma_addr))
 		goto out_dma_err;
 	vp->tx_ring[entry].addr = cpu_to_le32(dma_addr);

Regards,
Sylvain "ythier" Hitier

-- 
Business is about being busy, not being rich...
Lived 777 days in a Debian package => http://en.wikipedia.org/wiki/Apt,_Vaucluse
There's THE room for ideals in this mechanical place!
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