linux-kernel - Re: [PATCH] crypto: qat - remove redundant condition accel_dev->is

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Date:   Fri, 25 Oct 2019 17:45:31 +0800
From:   Yunfeng Ye <yeyunfeng@...wei.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
CC:     Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>, <qat-linux@...el.com>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "hushiyuan@...wei.com" <hushiyuan@...wei.com>,
        "linfeilong@...wei.com" <linfeilong@...wei.com>
Subject: Re: [PATCH] crypto: qat - remove redundant condition accel_dev->is_vf



On 2019/10/25 17:33, Ard Biesheuvel wrote:
> On Fri, 25 Oct 2019 at 09:24, Yunfeng Ye <yeyunfeng@...wei.com> wrote:
>>
>> Warning is found by the code analysis tool:
>>   "Redundant condition: accel_dev->is_vf"
>>
>> So remove the redundant condition accel_dev->is_vf.
>>
>> Signed-off-by: Yunfeng Ye <yeyunfeng@...wei.com>
>> ---
>>  drivers/crypto/qat/qat_common/adf_dev_mgr.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/crypto/qat/qat_common/adf_dev_mgr.c b/drivers/crypto/qat/qat_common/adf_dev_mgr.c
>> index 2d06409bd3c4..b54b8850fe20 100644
>> --- a/drivers/crypto/qat/qat_common/adf_dev_mgr.c
>> +++ b/drivers/crypto/qat/qat_common/adf_dev_mgr.c
>> @@ -196,7 +196,7 @@ int adf_devmgr_add_dev(struct adf_accel_dev *accel_dev,
>>         atomic_set(&accel_dev->ref_count, 0);
>>
>>         /* PF on host or VF on guest */
>> -       if (!accel_dev->is_vf || (accel_dev->is_vf && !pf)) {
>> +       if (!accel_dev->is_vf || !pf) {
> 
> I disagree with this change. There is no bug here, and the way the
> condition is formulated self-documents the code, i.e.,
> 
> IF NOT is_vf
> OR (is_vf BUT NOT pf)
> 
> Using an automated tool to reduce every boolean expression to its
> minimal representation doesn't seem that useful to me, since the
> compiler is perfectly capable of doing that when generating the object
> code.
> 
ok, thanks, this modify just fix warning, and make code simple.

> 
> 
> 
>>                 struct vf_id_map *map;
>>
>>                 list_for_each(itr, &accel_table) {
>> @@ -292,7 +292,7 @@ void adf_devmgr_rm_dev(struct adf_accel_dev *accel_dev,
>>                        struct adf_accel_dev *pf)
>>  {
>>         mutex_lock(&table_lock);
>> -       if (!accel_dev->is_vf || (accel_dev->is_vf && !pf)) {
>> +       if (!accel_dev->is_vf || !pf) {
>>                 id_map[accel_dev->accel_id] = 0;
>>                 num_devices--;
>>         } else if (accel_dev->is_vf && pf) {
>> --
>> 2.7.4
>>
> 
> .
>