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From:   Valentin Schneider <vschneid@redhat.com>
To:     Yury Norov <yury.norov@gmail.com>
Cc:     netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org, Saeed Mahameed <saeedm@nvidia.com>,
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        Jesse Brandeburg <jesse.brandeburg@intel.com>
Subject: Re: [PATCH v4 2/7] cpumask: Introduce for_each_cpu_andnot()
In-Reply-To: <YzBycCwecSUlGgjX@yury-laptop>
References: <20220923132527.1001870-1-vschneid@redhat.com>
 <20220923155542.1212814-1-vschneid@redhat.com>
 <YzBycCwecSUlGgjX@yury-laptop>
Date:   Tue, 27 Sep 2022 17:45:04 +0100
Message-ID: <xhsmhill84vhr.mognet@vschneid.remote.csb>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On 25/09/22 08:23, Yury Norov wrote:
> On Fri, Sep 23, 2022 at 04:55:37PM +0100, Valentin Schneider wrote:
>> +/**
>> + * for_each_cpu_andnot - iterate over every cpu present in one mask, excluding
>> + *			 those present in another.
>> + * @cpu: the (optionally unsigned) integer iterator
>> + * @mask1: the first cpumask pointer
>> + * @mask2: the second cpumask pointer
>> + *
>> + * This saves a temporary CPU mask in many places.  It is equivalent to:
>> + *	struct cpumask tmp;
>> + *	cpumask_andnot(&tmp, &mask1, &mask2);
>> + *	for_each_cpu(cpu, &tmp)
>> + *		...
>> + *
>> + * After the loop, cpu is >= nr_cpu_ids.
>> + */
>> +#define for_each_cpu_andnot(cpu, mask1, mask2)				\
>> +	for ((cpu) = -1;						\
>> +		(cpu) = cpumask_next_andnot((cpu), (mask1), (mask2)),	\
>> +		(cpu) < nr_cpu_ids;)
>
> This would raise cpumaks_check() warning at the very last iteration.
> Because cpu is initialized insize the loop, you don't need to check it
> at all. You can do it like this:
>
>  #define for_each_cpu_andnot(cpu, mask1, mask2)				\
>          for_each_andnot_bit(...)
>
> Check this series for details (and please review).
> https://lore.kernel.org/all/20220919210559.1509179-8-yury.norov@gmail.com/T/
>

Thanks, I'll have a look.

> Thanks,
> Yury