linux-kernel - Re: [Patch] vmbus: Simply hv_get_next_write

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Date:   Wed, 24 Jan 2018 08:37:07 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     lantianyu1986@...il.com
Cc:     sthemmin@...rosoft.com, haiyangz@...rosoft.com,
        linux-kernel@...r.kernel.org, devel@...uxdriverproject.org,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>
Subject: Re: [Patch] vmbus: Simply hv_get_next_write_location() function

On Wed, 24 Jan 2018 14:21:30 +0800
lantianyu1986@...il.com wrote:

> From: Tianyu Lan <Tianyu.Lan@...rosoft.com>
> 
> The "next" variable is redundant in hv_get_next_write_location().
> This patch is to remove it and return write_index directly.
> 
> Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
> ---
>  drivers/hv/ring_buffer.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> index 12eb8ca..71558e7 100644
> --- a/drivers/hv/ring_buffer.c
> +++ b/drivers/hv/ring_buffer.c
> @@ -82,9 +82,7 @@ static void hv_signal_on_write(u32 old_write, struct vmbus_channel *channel)
>  static inline u32
>  hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
>  {
> -	u32 next = ring_info->ring_buffer->write_index;
> -
> -	return next;
> +	return ring_info->ring_buffer->write_index;
>  }
>  
>  /* Set the next write location for the specified ring buffer. */

Looks good.
But let's go farther since function is only used in one location in the file
just eliminate it completely and do simple variable references.

The get/set functions in this file are unnecessary.

Better still it is possible to replace the lock based ring structure
with a compare-exchange solution.