linux-kernel - Re: [PATCH] hv: use substraction to update ring buffer index

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Message-ID: <20170105114804.GE13756@mwanda>
Date:   Thu, 5 Jan 2017 14:48:04 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Long Li <longli@...hange.microsoft.com>
Cc:     devel@...uxdriverproject.org,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hv: use substraction to update ring buffer index

On Thu, Jan 05, 2017 at 02:39:55PM +0300, Dan Carpenter wrote:
> > @@ -179,7 +180,8 @@ static u32 hv_copyfrom_ringbuffer(
> >  	memcpy(dest, ring_buffer + start_read_offset, destlen);
> >  
> >  	start_read_offset += destlen;
> > -	start_read_offset %= ring_buffer_size;
> > +	if (start_read_offset >= ring_buffer_size)
> > +		start_read_offset -= ring_buffer_size;
> 
> I totally don't understand the original code here.  We do the memset

I meant memcpy() not memset.

regards,
dan carpenter