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Subject: Re: [PATCH] misc: rtsx: Set setting_reg2 before use.
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     arnd@arndb.de, gregkh@linuxfoundation.org, ndesaulniers@google.com,
        ricky_wu@realtek.com, kai.heng.feng@canonical.com,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev
References: <20220516130047.3887590-1-trix@redhat.com>
 <YoJ0I/XPoj1B/+mm@dev-arch.thelio-3990X>
From:   Tom Rix <trix@redhat.com>
Message-ID: <d34498ad-0230-7c73-8f1f-9ca59fbf930f@redhat.com>
Date:   Mon, 16 May 2022 10:06:06 -0700
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On 5/16/22 8:56 AM, Nathan Chancellor wrote:
> On Mon, May 16, 2022 at 09:00:47AM -0400, Tom Rix wrote:
>> The clang build fails with
>> rts5261.c:406:13: error: variable 'setting_reg2' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>>          } else if (efuse_valid == 0) {
>>                     ^~~~~~~~~~~~~~~~
>>
>> setting_reg2 is set in this block
>>    if (efuse_valid == 2 || efuse_valid == 3) {
>> ..
>>    } else if (efuse_valid == 0) {
>>      // default
>> ..
>>    }
>> But efuse_valid can also have a value of 1.
>> Change the 'else if' to 'else' to make the second block the default.
>>
>> Fixes: b1c5f3085149 ("misc: rtsx: add rts5261 efuse function")
>> Signed-off-by: Tom Rix <trix@redhat.com>
> I am not sure if this fix is correct from a functional standpoint (i.e.
> is treating efuse_valid == 1 the same as efuse_valid == 0 correct?) but
> it is better than not handling this value altogether. For what it's
> worth:

I looked at how the code used to work, this seemed better than 
initializing to NULL.

>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
>
> As a side note, it is unfortunate that this change made it into -next
> when there was an outstanding report about this warning:

 From the clang side, this is a build break and my static analysis infra 
goes down.

These build breaks seem to happening every week, is there a precommit 
clang gating test that could be done for -next ?

Tom

>
> https://lore.kernel.org/202205100220.WyAyhKap-lkp@intel.com/
>
>> ---
>>   drivers/misc/cardreader/rts5261.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/misc/cardreader/rts5261.c b/drivers/misc/cardreader/rts5261.c
>> index 749cc5a46d13..f22634b14dc8 100644
>> --- a/drivers/misc/cardreader/rts5261.c
>> +++ b/drivers/misc/cardreader/rts5261.c
>> @@ -403,7 +403,7 @@ static void rts5261_init_from_hw(struct rtsx_pcr *pcr)
>>   			setting_reg1 = PCR_SETTING_REG4;
>>   			setting_reg2 = PCR_SETTING_REG5;
>>   		}
>> -	} else if (efuse_valid == 0) {
>> +	} else {
>>   		// default
>>   		setting_reg1 = PCR_SETTING_REG1;
>>   		setting_reg2 = PCR_SETTING_REG2;
>> -- 
>> 2.27.0
>>
> Cheers,
> Nathan
>