linux-kernel - Re: [PATCH] RDMA/mlx4: Use bitmap

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Message-ID: <142324ab-7696-e43d-2368-a18abebe7b09@wanadoo.fr>
Date:   Thu, 25 Nov 2021 21:10:02 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Joe Perches <joe@...ches.com>, yishaih@...dia.com,
        selvin.xavier@...adcom.com, dledford@...hat.com, jgg@...pe.ca
Cc:     linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] RDMA/mlx4: Use bitmap_alloc() when applicable

Le 25/11/2021 à 20:58, Joe Perches a écrit :
> On Thu, 2021-11-25 at 20:42 +0100, Christophe JAILLET wrote:
>> Use 'bitmap_alloc()' to simplify code, improve the semantic and avoid some
>> open-coded arithmetic in allocator arguments.
>>
>> Also change the corresponding 'kfree()' into 'bitmap_free()' to keep
>> consistency.
> 
> Thanks.
> 
>> diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
> []
>> @@ -2784,10 +2784,8 @@ static void *mlx4_ib_add(struct mlx4_dev *dev)
>>   		if (err)
>>   			goto err_counter;
>>   
>> -		ibdev->ib_uc_qpns_bitmap =
>> -			kmalloc_array(BITS_TO_LONGS(ibdev->steer_qpn_count),
>> -				      sizeof(long),
>> -				      GFP_KERNEL);
>> +		ibdev->ib_uc_qpns_bitmap = bitmap_alloc(ibdev->steer_qpn_count,
>> +							GFP_KERNEL);
> 
> I wonder if it'd be simpler/smaller to change this to bitmap_zalloc and
> remove the bitmap_zero in the if below.
> 

I asked myself the same question.
It is easy to see that the bitmap is either cleared or set.
So this is fine enough for me.

Let see if a maintainer has a preference on it.

CJ