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Re: [PATCH] of: of_mdio: Fix some endianness problems.

To: Grant Likely <grant.likely@secretlab.ca>
Subject: Re: [PATCH] of: of_mdio: Fix some endianness problems.
From: Sergei Shtylyov <sshtylyov@mvista.com>
Date: Mon, 01 Nov 2010 14:44:00 +0300
Cc: David Daney <ddaney@caviumnetworks.com>, linux-mips@linux-mips.org, ralf@linux-mips.org, devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org, Jeremy Kerr <jeremy.kerr@canonical.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Dan Carpenter <error27@gmail.com>, Greg Kroah-Hartman <gregkh@suse.de>
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Hello.

On 31-10-2010 5:54, Grant Likely wrote:

In of_mdiobus_register(), the __be32 *addr variable is dereferenced.
This will not work on little-endian targets.  Also since it is
unsigned, checking for less than zero is redundant.

Fix these two issues.

Signed-off-by: David Daney<ddaney@caviumnetworks.com>
Cc: Grant Likely<grant.likely@secretlab.ca>
Cc: Jeremy Kerr<jeremy.kerr@canonical.com>
Cc: Benjamin Herrenschmidt<benh@kernel.crashing.org>
Cc: Dan Carpenter<error27@gmail.com>
Cc: Greg Kroah-Hartman<gregkh@suse.de>
---
  drivers/of/of_mdio.c |   23 ++++++++++++++---------
  1 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index 1fce00e..b370306 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -52,27 +52,32 @@ int of_mdiobus_register(struct mii_bus *mdio, struct 
device_node *np)

       /* Loop over the child nodes and register a phy_device for each one */
       for_each_child_of_node(np, child) {
-             const __be32 *addr;
+             const __be32 *paddr;
+             u32 addr;
               int len;

               /* A PHY must have a reg property in the range [0-31] */
-             addr = of_get_property(child, "reg",&len);
-             if (!addr || len<  sizeof(*addr) || *addr>= 32 || *addr<  0) {
+             paddr = of_get_property(child, "reg",&len);
+             if (!paddr || len<  sizeof(*paddr)) {
+addr_err:
                       dev_err(&mdio->dev, "%s has invalid PHY address\n",
                               child->full_name);
                       continue;
               }
+             addr = be32_to_cpup(paddr);
+             if (addr>= 32)
+                     goto addr_err;

goto's are fine for jumping to the end of a function to unwind
allocations, but please don't use it in this manner.  The original
structure will actually work just fine if you do it thusly:

                if (!paddr || len<  sizeof(*paddr) ||
                    *(addr = be32_to_cpup(paddr))>= 32) {
                        dev_err(&mdio->dev, "%s has invalid PHY address\n",
                                child->full_name);
                        continue;
                }

Otherwise this patch looks good. After you've reworked and retested
I'll pick it up for 2.6.37 (or dave will).

Actually, I mistyped this.  I think it should be:

                if (!paddr || len<  sizeof(*paddr) ||
                    (addr = be32_to_cpup(paddr))>= 32) {

  This assignment would probably cause checkpatch.pl to complain...

WBR, Sergei

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