Re: [PATCH 3/4][v2] fsl_rio: move machine_check handler into machine_check_e500 & machine_check_e500mc

[Kumar Gala]

On Nov 11, 2010, at 4:19 AM, Xie Shaohui-B21989 wrote:

> 
> 
> 
> Best Regards, 
> Shaohui Xie 
> 
> 
>> -----Original Message-----
>> From: Bounine, Alexandre [mailto:Alexandre.Bounine@xxxxxxx]
>> Sent: Thursday, November 11, 2010 6:55 AM
>> To: Xie Shaohui-B21989; akpm@xxxxxxxxxxxxxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; Li
> Yang-
>> R58472; Gala Kumar-B11780; Zang Roy-R61911
>> Subject: RE: [PATCH 3/4][v2] fsl_rio: move machine_check handler into
>> machine_check_e500 & machine_check_e500mc
>> 
>> Shaohui Xie <b21989@xxxxxxxxxxxxx> wrote:
>>> 
>>> diff --git a/arch/powerpc/kernel/traps.c
> b/arch/powerpc/kernel/traps.c
>>> index a45a63c..2a5fb9d 100644
>>> --- a/arch/powerpc/kernel/traps.c
>>> +++ b/arch/powerpc/kernel/traps.c
>>> @@ -55,6 +55,7 @@
>>> #endif
>>> #include <asm/kexec.h>
>>> #include <asm/ppc-opcode.h>
>>> +#include <linux/rio.h>
>>> 
>>> #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)  int
>>> (*__debugger)(struct pt_regs *regs) __read_mostly; @@ -500,6 +501,13
>>> @@ int machine_check_e500mc(struct pt_regs *regs)
>>> 		       reason & MCSR_MEA ? "Effective" : "Physical",
>> addr);
>>> 	}
>>> 
>>> +	if (reason & MCSR_BUS_RBERR) {
>>> +		printk("Bus - Read Data Bus Error\n"); #ifdef
> CONFIG_RAPIDIO
>>> +		recoverable = fsl_rio_mcheck_exception(regs); #endif
>>> +	}
>>> +
>>> 	mtspr(SPRN_MCSR, mcsr);
>>> 	return mfspr(SPRN_MCSR) == 0 && recoverable;  } @@ -527,8
> +535,12
>> @@
>>> int machine_check_e500(struct pt_regs *regs)
>>> 		printk("Bus - Write Address Error\n");
>>> 	if (reason & MCSR_BUS_IBERR)
>>> 		printk("Bus - Instruction Data Error\n");
>>> -	if (reason & MCSR_BUS_RBERR)
>>> +	if (reason & MCSR_BUS_RBERR) {
>>> 		printk("Bus - Read Data Bus Error\n");
>>> +#ifdef CONFIG_RAPIDIO
>>> +		fsl_rio_mcheck_exception(regs);
>>> +#endif
>>> +	}
>>> 	if (reason & MCSR_BUS_WBERR)
>>> 		printk("Bus - Read Data Bus Error\n");
>>> 	if (reason & MCSR_BUS_IPERR)
>> 
>> This implementation breaks an intended use of
>> fsl_rio_mcheck_exception():
>> 1. for e500 it does not check the return value of the rio handler and
>> crashes the system even after RIO Mchk was serviced. Looks like e500mc
>> version handles it better but I have no HW to test it.
>> 2. the RIO Mchk is expected to be handled quietly but here it has many
>> printk's. May be it is better to call the fsl_rio_mcheck_exception()
>> handler in very beginning and simply exit if it returns 1.
>> 
>> Alex.
> [Xie Shaohui-B21989] Hi Alex, seems your suggestion is some kind of
> conflict with Kumar, you can have a look at 
> http://patchwork.ozlabs.org/patch/67774/

I think Alex's comment is the fact we ignore the 'return' value in the machine_check_e500 case.

- k--
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