linux-kernel - Re: [PATCH 5/5] misc: mlx5ctl: Add umem reg/unreg ioctl

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Date:   Sun, 19 Nov 2023 01:49:27 -0800
From:   Saeed Mahameed <saeed@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        Leon Romanovsky <leonro@...dia.com>,
        Jason Gunthorpe <jgg@...dia.com>, Jiri Pirko <jiri@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>
Subject: Re: [PATCH 5/5] misc: mlx5ctl: Add umem reg/unreg ioctl

On 18 Oct 10:33, Greg Kroah-Hartman wrote:
>On Wed, Oct 18, 2023 at 01:19:41AM -0700, Saeed Mahameed wrote:
> +#define MLX5CTL_UMEM_MAX_MB 64
>> +
>> +static size_t umem_num_pages(u64 addr, size_t len)
>> +{
>> +	return (size_t)((ALIGN(addr + len, PAGE_SIZE) -
>> +			 ALIGN_DOWN(addr, PAGE_SIZE))) /
>> +			 PAGE_SIZE;
>> +}
>
>We don't have a function or macro for this already?
>

I looked around and saw similar implementations, but nothing generic,
each has different assumptions, for example PAGE_SIZE can be different
or base address is assumed to be PAGE aligned, or len has a specific
alignment, so each use is a bit different.

I managed to reduce this to a one liner in V2.

Thanks,
Saeed.