Re: [PATCH] smc91c92_cs : add a spinlock to avoid race condition

[David Miller]

From: Vaishali Thakkar <vaishali.thakkar@xxxxxxxxxx>
Date: Fri, 19 Aug 2016 10:11:32 +0530

> 
> 
> On Friday 19 August 2016 09:37 AM, David Miller wrote:
>> From: Pavel Andrianov <andrianov@xxxxxxxxx>
>> Date: Tue, 16 Aug 2016 16:39:06 +0300
>> 
>>> smc_reset may be executed in parallel with timer function media_check.
>>> To avoid data race in smc_set_xcvr a spinlock was added.
>>>
>>> Found by Linux Driver Verification project (linuxtesting.org).
>>>
>>> Signed-off-by: Pavel Andrianov <andrianov@xxxxxxxxx>
>> 
>> This is not sufficient.
>> 
>> You have to block basically the entire function, because both
>> smc_reset and media_check program the bank selection so could
>> corrupt eachother's register accesses.
> 
> Hmm, but then there is a use of udelay as well. Would it be still
> fine to acquire a spinlock on whole function?

I don't know, but what I'm telling you is that you have to execute
register programming these two functions do atomically so that the
bank selection doesn't check get changed midstream.