netdev - Re: [PATCH] cxgb4: fix invalid checks in alloc_uld

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Date:   Tue, 23 Aug 2016 10:01:59 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Hariprasad Shenai <hariprasad@...lsio.com>
Cc:     "open list:CXGB4 ETHERNET DRIVER (CXGB4)" <netdev@...r.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cxgb4: fix invalid checks in alloc_uld_rxqs

On 08/23/2016 09:46 AM, Hariprasad Shenai wrote:
> On Tuesday, August 08/23/16, 2016 at 08:16:19 +0200, Andrzej Hajda wrote:
>> Local variable msi_idx defined as unsigned int is always >= 0, thus both
>> 'if' checks are always true. On the other side presence of USING_MSIX flag
>> suggests the checks should not be trivially true.
>> The simplest solution is to replace incorrect checks with direct testing
>> of adap->flags and remove spare variables.
>>
>> The problem has been detected using semantic patch
>> scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci
>>
> The correct fix is to have local variable 'msi_idx' as int instead of unsigned
> int. Thanks for reporting the issue. Do you want me to send a V2?
>
> Thanks,
> Hari
>
>
If adap->flags is constant during the call I see no point in creating
separate

variable with complicated initialization used only for the same thing as

'adap->flags & USING_MSIX', and even if adap->flags changes during the call

much simpler would be to use local var:

    int using_msix = adap->flags & USING_MSIX;

and later use tests:

    if (using_msix)

        ...

Am I correct?


Regards

Andrzej