linux-kernel - Re: [PATCH v2 09/19] ARM: at91: make sdram/ddr register base soc independent

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Date:	Thu, 23 Feb 2012 10:58:40 +0100
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	Ryan Mallon <rmallon@...il.com>, plagnioj@...osoft.com
CC:	linux@....linux.org.uk, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 09/19] ARM: at91: make sdram/ddr register base soc
 independent

On 02/23/2012 09:56 AM, Nicolas Ferre :
> On 02/22/2012 11:33 PM, Ryan Mallon :
>> On 22/02/12 20:39, Nicolas Ferre wrote:
>>
>>> From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
>>>
>>> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
>>> Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
>>> ---
>>
>> <snip>
>>
>>> +void __init at91_ioremap_ramc(int id, u32 addr, u32 size)
>>> +{
>>> +	if (id > 1) {
>>> +		pr_warn("%s: id > 2\n", __func__);
>>> +		return;
>>> +	}
>>> +	at91_ramc_base[id] = ioremap(addr, size);
>>> +	if (!at91_ramc_base[id])
>>> +		pr_warn("Impossible to ioremap ramc.%d 0x%x\n", id, addr);
>>> +}
>>
>>
>> If this fails then you will oops if you call either at91_ramc_read or
>> at91_ramc_write since they don't check if at91_ramc_base[id] is a valid
>> pointer. Either this function should panic, like the other at91_ioremap
>> functions, or the at91_ramc_read/write functions should check for a
>> valid pointer.
> 
> Yes, as you pointed out, it is done in a not-related following patch.
> I will bring the code here.
> 
> 
>> Nitpick: The id check should probably also be BUG() or WARN() since it
>> indicates a bug in the core AT91 code. pr_warn is likely to missed and
>> not reported by users. Since the value is int, the check should be:
>>
>>   if (id < 0 || id > 1)
>>
>> Obviously the chance of this error happening are slim, but if you are
>> going to check and warn for it, it should be done properly :-).
> 
> Yes, I agree and modify it at the very moment.


What do you think about that:
If id is not setup properly, I try to find a way out by using id = 0...
Then, a panic is added if the iremap() fails.


--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -200,13 +200,14 @@ void __iomem *at91_ramc_base[2];
 
 void __init at91_ioremap_ramc(int id, u32 addr, u32 size)
 {
-       if (id > 1) {
-               pr_warn("%s: id > 2\n", __func__);
-               return;
+       if (id < 0 || id > 1) {
+               WARN(1, "%s: Wrong RAM controller id (%d), set it to 0\n",
+                                                               __func__, id);
+               id = 0;
        }
        at91_ramc_base[id] = ioremap(addr, size);
        if (!at91_ramc_base[id])
-               pr_warn("Impossible to ioremap ramc.%d 0x%x\n", id, addr);
+               panic("Impossible to ioremap ramc.%d 0x%x\n", id, addr);
 }
 
 static int at91_pm_enter(suspend_state_t state)

Best regards,
-- 
Nicolas Ferre
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