linux-kernel - Re: [PATCH -next] ring-buffer: Fix ring buffer size in rb_write

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Date:   Mon, 25 Mar 2019 21:36:07 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     YueHaibing <yuehaibing@...wei.com>
Cc:     Ingo Molnar <mingo@...hat.com>, <linux-kernel@...r.kernel.org>,
        <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH -next] ring-buffer: Fix ring buffer size in
 rb_write_something

On Sun, 23 Sep 2018 12:11:33 +0000
YueHaibing <yuehaibing@...wei.com> wrote:

> 'cnt' should be used to calculate ring buffer size rather than data->cnt

I just found this patch in my inbox (was traveling at the time. But now
I have patchwork attached to my INBOX so patches like these shouldn't
be missed anymore!)

Yes, you are correct, this should be fixed. But as it is just for a
startup test, I'll queue it for the next merge window.

Thanks and sorry for the delay.

-- Steve

> 
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
> ---
>  kernel/trace/ring_buffer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 65bd461..53538c3 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -4924,7 +4924,7 @@ static __init int rb_write_something(struct
> rb_test_data *data, bool nested) cnt = data->cnt + (nested ? 27 : 0);
>  
>  	/* Multiply cnt by ~e, to make some unique increment */
> -	size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1);
> +	size = (cnt * 68 / 25) % (sizeof(rb_string) - 1);
>  
>  	len = size + sizeof(struct rb_item);
>  
> 
>