linux-kernel - Re: [PATCH] regulator: max8925: fix compiler warnings

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Date:	Mon, 26 Nov 2012 11:07:25 +0800
From:	Qing Xu <qingx@...vell.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	"lrg@...com" <lrg@...com>,
	"haojian.zhuang@...il.com" <haojian.zhuang@...il.com>,
	Chao Xie <cxie4@...vell.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] regulator: max8925: fix compiler warnings

On 11/25/2012 01:55 AM, Mark Brown wrote:
> On Fri, Nov 23, 2012 at 10:27:12AM +0800, Qing Xu wrote:
>
>> But, in fact, it is not necessary to initialize regulator_idx.
>>          for (i = 0; i < ARRAY_SIZE(max8925_regulator_info); i++) {
>>                  ri = &max8925_regulator_info[i];
>>                  if (ri->vol_reg == res->start) {
>> ****** if regulator_idx can not get a match "i" here, it will return
>> -EINVAL in below code
>>                          regulator_idx = i;
>>                          break;
>>                  }
>>          }
>>          if (i == ARRAY_SIZE(max8925_regulator_info)) {
>>                  dev_err(&pdev->dev, "Failed to find regulator %llu\n",
>>                          (unsigned long long)res->start);
>>                  return -EINVAL;
>>          }
>> How to solve such compiler warning?
> Typically by reporting a compiler bug, though sometimes in the process
> of doing that one finds out that there's some non-obvious way in which
> the code can break.

It seems not like a compiler bug, its logic is:

for(...; i<xxx; ...) {
     if (...) {
         regulator_idx = i
         break;
     }
}

if (i == xxx)
     return ERROR;

If regulator_idx can not get a matched "i" value, code will return ERROR.
But it seems that compiler can not do so complex judge.
And, I think the code is safe even if regulator_idx is not initialized, also
because of the "return ERROR" judge.



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