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

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Date:	Mon, 01 Nov 2010 14:44:00 +0300
From:	Sergei Shtylyov <sshtylyov@...sta.com>
To:	Grant Likely <grant.likely@...retlab.ca>
CC:	David Daney <ddaney@...iumnetworks.com>, linux-mips@...ux-mips.org,
	ralf@...ux-mips.org, devicetree-discuss@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	Jeremy Kerr <jeremy.kerr@...onical.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Dan Carpenter <error27@...il.com>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [PATCH] of: of_mdio: Fix some endianness problems.

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@...iumnetworks.com>
>>> Cc: Grant Likely<grant.likely@...retlab.ca>
>>> Cc: Jeremy Kerr<jeremy.kerr@...onical.com>
>>> Cc: Benjamin Herrenschmidt<benh@...nel.crashing.org>
>>> Cc: Dan Carpenter<error27@...il.com>
>>> Cc: Greg Kroah-Hartman<gregkh@...e.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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